SVM118-A
August, 1998
SQUARE WAVE TIG 355
For use with machines having Code Numbers: 9951
9952
9953
9954
9955
Safety Depends on You
Lincoln arc welding and cutting
equipment is designed and
built with safety in mind.
However, your overall safety
can be increased by proper
installation . . . and thoughtful
operation on your part. DO
NOT INSTALL, OPERATE OR
REPAIR THIS EQUIPMENT
WITHOUT READING THIS
MANUAL AND THE SAFETY
PRECAUTIONS CONTAINED
THROUGHOUT. And, most
importantly, think before you
act and be careful.
SERVICE MANUAL
World’s Leader in Welding and Cutting Products
Premier Manufacturer of Industrial Motors
Sales and Service through subsidiaries and Distributors Worldwide
22801 St. Clair Ave. Cleveland, Ohio 44117-1199 U.S.A. Tel. (216) 481-8100
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ii
ii
SAFETY
WELDING SPARKS can
cause fire or explosion.
CYLINDER may explode
if damaged.
4.a. Remove fire hazards from the weld-
ing area. If this is not possible,
cover them to prevent the welding
5.a. Use only compressed gas cylin-
ders containing the correct shield-
ing gas for the process used and
sparks from starting
a
fire.
properly operating regulators
Remember that welding
designed for the gas and
sparks and hot materials from welding can easily go through small
cracks and openings to adjacent areas. Avoid welding near
hydraulic lines. Have a fire extinguisher readily available.
4.b. Where compressed gases are to be used at the job site, spe-
cial precautions should be used to prevent hazardous situa-
tions. Refer to “Safety in Welding and Cutting” (ANSI
Standard Z49.1) and the operating information for the equip-
ment being used.
pressure used. All hoses, fittings, etc. should be suitable for the
application and maintained in good condition.
5.b. Always keep cylinders in an upright position securely
chained to an undercarriage or fixed support.
5.c. Cylinders should be located:
• Away from areas where they may be struck or subjected to
physical damage.
• A safe distance from arc welding or cutting operations and
any other source of heat, sparks, or flame.
4.c. When not welding, make certain no part of the electrode cir-
cuit is touching the work or ground. Accidental contact can
cause overheating and create a fire hazard.
5.d. Never allow the electrode, electrode holder or any other elec-
trically “hot” parts to touch a cylinder.
4.d. Do not heat, cut or weld tanks, drums or containers until the
proper steps have been taken to insure that such procedures
will not cause flammable or toxic vapors from substances
inside. They can cause an explosion even though they have
been “cleaned”. For information, purchase “Recommended
Safe Practices for the Preparation for Welding and Cutting of
Containers and Piping That Have Held Hazardous
Substances,” AWS F4.1 from the American Welding Society
(see address above).
5.e. Keep your head and face away from the cylinder valve outlet
when opening the cylinder valve.
5.f. Valve protection caps should always be in place and hand
tight except when the cylinder is in use or connected for use.
5.g. Read and follow the instructions on compressed gas cylin-
ders, associated equipment, and CGA publication P-I,
“Precautions for Safe Handling of Compressed Gases in
Cylinders,” available from the Compressed Gas Association
1235 Jefferson Davis Highway, Arlington, VA 22202.
4.e. Vent hollow castings or containers before heating, cutting or
welding. They may explode.
4.f. Sparks and spatter are thrown from the welding arc. Wear oil
free protective garments such as leather gloves, heavy shirt,
cuffless trousers, high shoes and a cap over your hair. Wear
eat plugs when welding out of position or in confined places.
Always wear safety glasses with side shields when in a weld-
ing area.
FOR ELECTRICALLY pow-
ered equipment.
6.a. Turn off input power using the dis-
connect switch at the fuse box
before working on the equipment.
4.g. Connect the work cable to the work as close to the welding
area as practical. Work cables connected to the building
framework or other locations away from the welding area
increase the possibility of the welding current passing
through lifting chains, crane cables or other alternate circuits.
This can create fire hazards or overheat lifting chains or
cables until they fail.
6.b. Install equipment in accordance with the U.S. National
Electrical Code, all local codes and the manufacturer’s rec-
ommendations.
6.c. Ground the equipment in accordance with the U.S. National
Electrical Code and the manufacturer’s recommendations.
4.h. Also see item 7c.
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iii
iii
SAFETY
FOR ENGINE
powered equipment.
ELECTRIC AND MAGNETIC
FIELDS
may be dangerous
7.a. Turn the engine off before troubleshooting and maintenance
work unless the maintenance work requires it to be running.
8.a. Electric current flowing through any conductor causes local-
ized Electric and Magnetic Fields (EMF). Welding current cre-
ates EMF fields around welding cables and welding
machines.
7.b.Operate engines in open, well-ventilated
areas or vent the engine exhaust fumes
outdoors.
8.b. EMF fields may interfere with some pacemakers, and welders
have a pacemaker should consult their physician before
welding.
7.c. Do not add the fuel near an open flame
welding arc or when the engine is run-
ning. Stop the engine and allow it to cool
before refueling to prevent spilled fuel
from vaporizing on contact with hot
engine parts and igniting. Do not spill
fuel when filling tank. If fuel is spilled,
wipe it up and do not start engine until
fumes have been eliminated.
8.c. Exposure to EMF fields in welding may have other health
effects which are now not known.
8.d. All welders should use the following procedures in order to
minimize exposure to EMF fields from the welding circuit:
8.d.1. Route the electrode and work cables together -
Secure them with tape when possible.
8.d.2. Never coil the electrode lead around your body.
8.d.3. Do not place your body between the electrode and
work cables. If the electrode cable is on your right
side, the work cable should also be on your right side.
7.d. Keep all equipment safety guards, covers
and devices in position and in good
repair. Keep hands, air, clothing and
tools away from V-belts, gears, fans and
all other moving parts when starting,
operating, or repairing equipment.
8.d.4. Connect the work cable to the workpiece as close as
possible to the area being welded.
8.d.5. Do not work next to welding power source.
7.e. In some cases it may be necessary to remove safety guards
to perform required maintenance. Remove guards only when
necessary and replace them when the maintenance requiring
their removal is complete. Always use the greatest care when
working near moving parts.
7.f. Do not put your hands near the engine fan. Do not attempt
to override the governor or idler by pushing on the throttle
control rods while the engine is running.
7.g. To prevent accidentally starting gasoline engines while turn-
ing the engine or welding generator during maintenance
work, disconnect the spark plug wires, distributor cap or
magneto wire as appropriate.
7.h. To avoid scalding, do not remove the
radiator pressure cap when the engine
is hot.
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iv
iv
SAFETY
7. Quand on ne soude pas, poser la pince à une endroit isolé
PRÉCAUTIONS DE SÛRETÉ
de la masse. Un court-circuit accidental peut provoquer un
échauffement et un risque d’incendie.
Pour votre propre protection lire et observer toutes les instructions
et les précautions de sûreté specifiques qui parraissent dans ce
manuel aussi bien que les précautions de sûreté générales suiv-
antes:
8. S’assurer que la masse est connectée le plus prés possible
de la zone de travail qu’il est pratique de la faire. Si on place
la masse sur la charpente de la construction ou d’autres
endroits éloignés de la zone de travail, on augmente le
risque de voir passer le courant de soudage par les chaines
de levage, câbles de grue, ou atres circuits. Cela peut
provoquer des risques d’incendie ou d’echauffement des
chaines et des câbles jusqu’à ce qu’ils se rompent.
Sûreté Pour Soudage A L’Arc
1. Protegez-vous contre la secousse électrique:
a. Les circuits à l’électrode et à la piéce sont sous tension
quand la machine à souder est en marche. Eviter tou-
jours tout contact entre les parties sous tension et la
peau nue ou les vétements mouillés. Porter des gants
secs et sans trous pour isoler les mains.
9. Assurer une ventilation suffisante dans la zone de soudage.
Ceci est particuliérement important pour le soudage de tôles
galvanisées plombées, ou cadmiées ou tout autre métal qui
produit des fumées toxiques.
b. Faire trés attention de bien s’isoler de la masse quand
on soude dans des endroits humides, ou sur un planch-
er metallique ou des grilles metalliques, principalement
dans les positions assis ou couché pour lesquelles une
grande partie du corps peut être en contact avec la
masse.
10. Ne pas souder en présence de vapeurs de chlore provenant
d’opéerations de dégraissage, nettoyage ou pistolage. La
chaleur ou les rayons de l’arc peuvent réagir avec les
vapeurs du solvant pour produire du phosgéne (gas forte-
ment roxique) ou autres produits irritants.
c. Maintenir le porte-électrode, la pince de masse, le câble
de soudage et la machine à souder en bon et sûr état
defonctionnement.
PRÉCAUTIONS DE SÛRETÉ POUR LES
MACHINES À SOUDER À TRANSFOR-
MATEUR ET À REDRESSEUR
d. Ne jamais plonger le porte-électrode dans l’eau pour le
refroidir.
e. Ne jamais toucher simultanément les parties sous ten-
sion des porte-électrodes connectés à deux machines à
souder parce que la tension entre les deux pinces peut
être le total de la tension à vide des deux machines.
1. Relier à la terre le chassis du poste conformement au code
de l’électricité et aux recommendations du fabricant. Le dis-
positif de montage ou la piece à souder doit être branché à
une bonne mise à la terre.
2. Dans le cas de travail au dessus du niveau du sol, se protéger
contre les chutes dans le cas ou on recoit un choc. Ne jamais
enroule le câble-électrode autour de n’importe quelle partie
du corps.
2. Autant que possible, l’installation et l’entretien du poste
seront effectués par un électricien qualifié.
3. Avant de faires des travaux à l’interieur de poste, la
debrancher à l’interrupteur à la boite de fusibles.
3. Un coup d’arc peut être plus sévère qu’un coup de soliel,
donc:
4. Garder tous les couvercles et dispostifis de sûreté à leur
place.
a. Utiliser un bon masque avec un verre filtrant approprié
ainsi qu’un verre blanc afin de se protéger les yeux du
rayonnement de l’arc et des projections quand on soude
ou quand on regarde l’arc.
b. Porter des vêtements convenables afin de protéger la
peau de soudeur et des aides contre le rayonnementde
l’arc.
c. Protéger l’autre personnel travaillant à proximité au
soudage à l’aide d’écrans appropriés et non-inflamma-
bles.
4. Des gouttes de laiter en fusion sont émises de l’arc de
soudage. Se protéger avec es vêtements de protection libres
de l’huile, tels que les gants en cuir, chemise épaisse, pan-
talons sans revers, et chaussures montantes.
5. Toujours porter des lunettes de sécurité dans la zone de
soudage. Utiliser des lunettes avec écrans lateraux dans les
zones où l’on pique le laitier.
6. Eloigner les matériaux inflammables ou les recouvrir afin de
prévenir ttout risque d’incendie dû étincelles.
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v
v
MASTER TABLE OF CONTENTS FOR ALL SECTIONS
Page
Safety.................................................................................................................................................i-iv
Installation.............................................................................................................................Section A
Installation Section Table of Contents........................................................................................A-1
Technical Specifications .............................................................................................................A-2
Safety Precautions......................................................................................................................A-3
Select Suitable Location (Stacking, Tilting, Lifting) ....................................................................A-3
High Frequency Interference Protection.....................................................................................A-3
Input Connections.......................................................................................................................A-4
Reconnect Procedure.................................................................................................................A-5
Output Connections....................................................................................................................A-7
Operation...............................................................................................................................Section B
Safety Instructions......................................................................................................................B-2
General Description....................................................................................................................B-3
Recommended Processes..........................................................................................................B-3
Operational Features and Controls ............................................................................................B-3
Design Features and Advantages...............................................................................................B-3
Welding Capability......................................................................................................................B-4
Limitations .................................................................................................................................B-4
Controls and Settings (Upper and Lower Case Front Controls) ................................................B-5
Welding Operation ....................................................................................................................B-15
Overload Protection..................................................................................................................B-21
Auxiliary Power .........................................................................................................................B-21
Accessories...........................................................................................................................Section C
Maintenance .........................................................................................................................Section D
Safety Precautions......................................................................................................................D-2
Input Power Factor Capacitor Discharge Procedure .................................................................D-2
Routine and Periodic Maintenance ............................................................................................D-3
General Component Locations...................................................................................................D-4
Theory of Operation .............................................................................................................Section E
Troubleshooting and Repair.................................................................................................Section F
How To Use Troubleshooting Guide ...........................................................................................F-2
Troubleshooting Guide................................................................................................................F-4
Electrical Diagrams..............................................................................................................Section G
Parts Manual.................................................................................................................................P-196
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Section A-1
Section A-1
TABLE OF CONTENTS
- INSTALLATION SECTION -
Installation
Technical Specifications Square Wave TIG 355.........................................................................A-2
Input and Output Specifications ..........................................................................................A-2
Cable and Fuse Sizes...........................................................................................................A-2
Physical Dimensions ............................................................................................................A-2
Safety Precautions......................................................................................................................A-3
Select Suitable Location.............................................................................................................A-3
Stacking................................................................................................................................A-3
Lifting .................................................................................................................................A-3
Tilting .................................................................................................................................A-3
High Frequency Precautions.......................................................................................................A-3
Input Connections.......................................................................................................................A-4
Ground Connection..............................................................................................................A-4
Input Supply Connections....................................................................................................A-4
Reconnect Procedure.................................................................................................................A-5
Output Connections....................................................................................................................A-7
TIG Torch Connection ..........................................................................................................A-7
Stick Electrode Cable Connection .......................................................................................A-8
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A-2
A-2
INSTALLATION
TECHNICAL SPECIFICATIONS - SQUARE WAVE TIG 355
INPUT - SINGLE PHASE ONLY
Input Voltages:
208
230
460
575
Input Currents
@ 350A/34 VDC
110
100
50
40
RATED OUTPUT
Duty Cycle
Amps
Volts at Rated Amperes
40% Duty Cycle
60% Duty Cycle
100% Duty Cycle
350
300
220
34 v
32 v
29 v
OUTPUT
Maximum Open
Circuit Voltage
Continuous
Current Range
Auxiliary Power
80 Volts Max.
2-400 Amps AC and DC
115 VAC
15 Amps Continuous
RECOMMENDED INPUT WIRE AND FUSE SIZES
For Unbalanced AC TIG Welding Above 230 Amps,
300/32V/60% Duty Cycle, Unbalance Based on the
1990 U.S. National Electrical Code
For all Stick, DC TIG, and Balanced AC TIG
Welding at 350A/34V/40% Duty Cycle Based
on the 1990 U.S. National Electrical Code
Type 75°C
Type 75°C
Fuse
Input
Type75°C
Copper Ground
Type 75°C
Copper Ground
Fuse
Input
Voltage / or Breaker Rating on Conduit AWG
(Super Lag) Ampere Copper Wire in Wire in Conduit
Copper Wire in Wire in Conduit (Super LAG)
AWG (IEC)
Sizes
Input
Amperes
Conduit AWG
(IEC) Sizes
AWG (IEC)
Sizes
or Breaker
Size
Frequency
Size
150
125
60
Nameplate
(IEC) Sizes
4 (25mm2)
6 (16mm2)
8 (10mm2)
208/60
110
100
50
6 (16mm2)
6 (16mm2)
10 (6mm2)
148
134
67
2 (35mm2)
2 (35mm2)
6 (16mm2)
6 (16mm2)
6 (16mm2)
8 (10mm2)
200
175
80
230/60
460/60
575/60
50
40
8 (10mm2)
10 (6mm2)
54
6 (16mm2)
8 (10mm2)
70
PHYSICAL DIMENSIONS
Height
Width
Depth
Weight
884 mm
34.84 in.
565 mm
22.25 in.
660 mm
26.00 in.
232 kg
510 lbs.
OPERATING TEMPERATURE RANGE STORAGE TEMPERATURE RANGE
0° to 40°C
-50° to 85°C
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A-3
A-3
INSTALLATION
Read this entire installation section before you
start installation.
TILTING
Place the machine on a secure, level surface or on a
recommended undercarriage. Any surfaces you
place it on other than the ground must be firm, non-
skid, and structurally sound.
SAFETY PRECAUTIONS
WARNING
HIGH FREQUENCY INTERFERENCE
PROTECTION
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts
or electrodes with your skin or wet
clothing.
The spark gap oscillator in the high frequency genera-
tor, being similar to a radio transmitter, can be blamed
for many radio, TV and electronic equipment interfer-
ence problems. These problems may be the result of
radiated interference. Proper grounding methods can
reduce or eliminate radiated interference.
• Insulate yourself from the work
and ground.
• Always wear dry insulating gloves.
Only qualified personnel should install, use, or service
this equipment.
The Square Wave TIG 355 has been field tested under
recommended installation conditions. It complies with
FCC allowable limits for radiation. For convenience, a
certificate of compliance is packed with the welder. It
can be used to prove FCC RF Energy Radiation Limits
compliance if necessary. (It is the owner's responsi-
bility to obtain this certification.) The Square Wave TIG
355 also complies with NEMA standards for high fre-
quency stabilized power sources.
SELECT SUITABLE LOCATION
Place the Square Wave TIG 355 where clean, cooling
air can flow freely in through the side louvers and out
through the rear louvers. Keep dust, dirt, and other
foreign materials that can be drawn into the machine
to a minimum. Failure to observe these precautions
can lead to excessive operating temperatures and
nuisance shut-downs. Read the section, "High
Frequency Interference Protection" before planning
the installation.
Radiated interference can develop in the following four
ways:
1. Direct interference radiated from the welder.
2. Direct interference radiated from the welding leads.
3. Direct interference radiated from feedback into the
power lines.
STACKING
4. Interference from re-radiation of “pickup” by
ungrounded metallic objects.
Square Wave TIG 355s may be stacked two high.
The bottom machine must be on a stable, hard, level
surface. Be sure that the two pins in the roof of the
bottom machine fit into the holes in the base of the
top machine.
Keeping these contributing factors in mind, installing
equipment per the following instructions should mini-
mize problems.
1. Keep the welder power supply lines as short as
possible and completely enclose them in rigid
metallic conduit or equivalent shielding for a mini-
mum distance of 50 feet (15.2m). There should be
good electrical contact between this conduit and
the welder. Both ends of the conduit should be
connected to a driven ground and the entire length
should be continuous.
LIFTING
WARNING
CYLINDER MAY EXPLODE if damaged.
• Do not lift the welder with a cylinder attached.
2. Keep the work and electrode leads as short as pos-
sible and as close together as possible. Lengths
should not exceed 25 ft (7.6m). Tape the leads
together when practical.
The Square Wave TIG 355 weighs 510 lbs. (232 kg)
without a gas cylinder. Lift the machine by the lift
bail only. Never lift the machine with a cylinder
attached.
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A-4
A-4
INSTALLATION
3. Be sure the torch and work cable rubber coverings
are free of cuts and cracks that allow high fre-
quency leakage. Cables with high natural rubber
content, such as Lincoln Stable-Arc® better resist
high frequency leakage than neoprene and other
synthetic rubber insulated cables.
FIGURE A.1 – REAR PANEL
2
3
4. Keep the torch in good repair and all connections
tight to reduce high frequency leakage.
5. The work terminal must be connected to a ground
within ten feet of the welder, using one of the fol-
lowing methods.
a) A metal underground water pipe in direct con-
tact with the earth for ten feet or more.
b) A 3/4” (19mm) galvanized pipe or a 5/8”
(16mm) solid galvanized iron, steel or copper
rod driven at least eight feet into the ground.
The ground should be securely made and the
grounding cable should be as short as possible
using cable of the same size as the work cable, or
larger. Grounding to the building frame electrical
conduit or a long pipe system can result in re-radi-
ation, effectively making these members radiating
antennas.
1. WARNING DECAL
2. INPUT POWER ENTRY
3. RECONNECT PANEL COVER
GROUND CONNECTION
The frame of the welder must be
grounded. A ground terminal marked
with the symbol is located at the bot-
6. Keep all access panels and covers securely in
place.
tom of the input box for this purpose.
See your local and national electrical
codes for proper grounding methods.
7. All electrical conductors within 50 ft (15.2m) of the
welder should be enclosed in grounded, rigid
metallic conduit or equivalent shielding. Flexible
metallic conduit is generally not suitable.
Also follow other grounding instructions given in the
section “High Frequency Interference Protection.”
8. When the welder is enclosed in a metal buidling,
several good earth driven electrical grounds (as in
5 (b) above) around the periphery of the building
are recommended.
INPUT SUPPLY CONNECTION
Be sure the voltage, phase, and frequency of the input
power is as specified on the welder nameplate.
Failure to observe these recommended installation
procedures can cause radio or TV interference
problems and result in unsatisfactory welding per-
formance resulting from lost high frequency
power.
WARNING
ELECTRIC SHOCK can kill.
• Have a qualified electrician install
and service this equipment.
• Turn the input power off at the fuse
box before working on this equip-
ment.
INPUT CONNECTIONS
Be sure the voltage, phase, and frequency of the input
power is as specified on the rating plate, located on
the front of the machine.
• Do not touch electrically hot parts.
Have a qualified electrician connect the input power
leads to L1 and L2 of the input contactor in accor-
dance with all local codes and national electrical
codes. Use a single phase line or one phase of a two
or three phase line. Refer to the connection diagram
located on the inside of the cover of the Reconnect
Panel. Also see Figure A.2.
Welder supply line entry provision is in the case rear
panel with a removable cover over the input connec-
tion panel area. See Figure A.1.
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A-5
A-5
INSTALLATION
FIGURE A.2 – INPUT SUPPLY CONNECTIONS
Refer to Figure A.2 for the following procedure.
Welders are shipped connected for the highest input
voltage listed on the rating plate. To change this con-
nection for a different input voltage, reconnect both
the power strap (P) and control lead (C) to their
respective terminals corresponding to the input volt-
age used. Designations on reconnect panel, LOW,
MID and HIGH, correspond to the nameplate input
voltages of a triple voltage welder. Dual voltage
welders use only LOW and HIGH. Single voltage
welders use only HIGH.
WARNING
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts
or electrodes with your skin or wet
clothing.
• Insulate yourself from the work and ground.
• Always wear dry insulating gloves.
EXAMPLE: On a 208/230/460 volt welder, LOW is
208V, MID is 230V, and HIGH is 460V.
RECONNECT PROCEDURE
Fuse the input circuit with the recommended super lag
fuses or delay type1 circuit breakers. Choose an input
and grounding wire size according to local or national
codes or refer to Tables A.1 and A.2. Using fuses or
circuit breakers smaller than recommended may result
in “nuisance” shut-offs from welder inrush currents
even if not welding at high curents.
On multiple input voltage welders, be sure the recon-
nect panel is connected according to the following
instructions for the voltage being supplied to the
welder.
CAUTION
Unbalanced AC TIG welding draws higher input cur-
rents than those for stick, DC TIG, or Balanced AC TIG
welding. The welder is designed for these higher input
currents. However, where unbalanced AC TIG welding
above 230 amps is planned, the higher input currents
require larger input wire sizes and fuses. See Table
A.2.
Failure to follow these instructions can cause immedi-
ate failure of components within the welder.
1Also called “inverse time” or “thermal/magnetic” circuit breakers.
These circuit breakers have a delay in tripping action that decreases
as the magnitude of the current increases.
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A-6
A-6
INSTALLATION
The Square Wave TIG 355 should be permanently
wired into the power system. Plugs or connectors are
not recommended.
TABLE A.1
RECOMMENDED INPUT WIRE AND FUSE SIZES
For all Stick, DC TIG, and Balanced AC TIG Welding
Based on the 1990 U.S. National Electrical Code(2)
40% Duty Cycle
Input Ampere
Rating on
Nameplate
Type 75°C
Wire in Conduit
AWG Copper Cond.
Input
Volt/Freq.
Grounding Wire
AWG Copper Cond.
Fuse Size
(Super Lag)
208/60
230/60
460/60
200/50
220/50
440/50
110
100
50
115
104
52
4
6
8
4
4
8
6
6
10
6
6
10
150
125
60
150
125
60
TABLE A.2
RECOMMENDED INPUT WIRE AND FUSE SIZES
For Unbalanced AC TIG Welding Above 230 AMPS
Based on the 1990 U.S. National Electrical Code(2)
60% Duty Cycle
Input Amperes
at 300 Amp
Unbalanced
AC Output
Type 75°C
Wire in Conduit
AWG Copper Cond.
Input
Volt/Freq.
Grounding Wire
AWG Copper Cond.
Fuse Size
(Super Lag)
208/60
230/60
460/60
200/50
220/50
440/50
148
134
67
154
140
70
2
2
6
1
2
6
6
6
8
6
6
8
200
175
80
200
200
90
(2) Article 630 of the 1990 U.S. National Electrical Code allows the rated ampacity of the supply conductors to be determined by multiplying
the nameplate rating by the appropriate multiplier, depending on the duty cycle of the welder.
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A-7
A-7
INSTALLATION
OUTPUT CONNECTIONS
WARNING
Observe the safety precautions necessary for handling
and using compressed gas containers. Contact your
supplier for specific information.
WARNING
ELECTRIC SHOCK can kill.
• Keep the electrode holder, TIG
FIGURE A.3 – FRONT PANEL
torch and cables insulation in
good condition and in place.
• Do not touch electrically live parts
or electrode with skin or wet
clothing.
• Insulate yourself from work and ground.
• Turn the power off pushbutton on the Square Wave
TIG 355 “off” before connecting or disconnecting
output cables or other equipment.
See Figure A.3 for the location of the work and elec-
trode terminals, the gas and optional water solenoids,
and the Remote Receptacle.
TIG TORCH CONNECTION
TIG welding torches come with 15 ft (4.6m) and 25 ft
(7.6m) cables. Use the shorter length whenever pos-
sible to minimize possible radio interference problems.
With power source off, connect the torch cable to the
“Electrode” terminal on the welder. Connect a sepa-
rate work cable to the “Work” terminal of the welder.
See Table A.3 for recommended work cable sizes.
Both work and electrode cables should be routed
through the cable strain relief holes provided in the
base directly below the welding ouput terminals.
1. REMOTE RECEPTACLE
2. WATER AND GAS
SOLENOIDS
3. WORK (LEFT) AND
ELECTRODE TERMINALS
Connect the TIG torch gas and water fittings to the
welder fittings. any torch with fittings that conform to
Compressed Gas Association (CGA) standards can be
used.
The welder fittings have the following threads: Gas
Inlet and Outlet: 5/8”-18 right-hand female; Water inlet
and Outlet: 5/8”-18 left-hand female. The cylinder of
inert shielding gas must be equipped with a pressure
regulator and flow meter. Install a hose between the
flow meter and gas inlet on the welder.
TABLE A.3
CABLE SIZES FOR COMBINED LENGTHS OF COPPER ELECTRODE AND WORK CABLE
Lengths up to
100 ft (30 m)
100 to 200 ft
(30 to 61 m)
200 to 250 ft
(61 to 76 m)
Machine Size
350 Amp
40% Duty Cycle
#1 (45mm2)
1/0 (55mm2)
2/0 (70mm2)
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A-8
A-8
INSTALLATION
DO NOT operate a water-cooled torch unless water is
flowing. Water doesn’t flow until the solenoid is actu-
ated.
STICK ELECTRODE CABLE
CONNECTION
Turn the Power switch Off. Run the electrode and
work cables through the strain relief holes below the
welding output terminals and connect the cables to
the proper terminals. This strain relief prevents dam-
age to the welding output terminals if the cables are
pulled excessively. Select cable size according to
Table A.3
If using a water-cooled torch with a Magnum water
cooler, connect the cooler water outlet to the “Water
Valve In” fitting. Connect the TIG torch inlet to the
“Water Valve Out” fitting.
If using a water-cooled torch with a free-running water
supply, install a water line between the welder “Water
Inlet” and the supply. Include a strainer in the water
supply line to prevent dirt particles from obstructing
water flow in the valve and cooling chamber of the TIG
torch. Failure to do so could result in water valve mal-
function and overheating of the water-cooled torch.
Connect the torch water line to the welder “Water Out”
fitting. Use a nonmetallic drain line from the electrode
connection to the drain or water recirculating pump.
WARNING
Do not connect a TIG torch and stick electrode cable
at the same time. They will both be electrically HOT
whenever the output terminals are energized.
For other water coolers or torches, consult the manu-
facturer’s instructions for the water cooler or TIG torch
being used.
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Section B-1
Section B-1
TABLE OF CONTENTS
- OPERATION SECTION -
Operation...............................................................................................................................Section B
Safety Instructions ...............................................................................................................B-2
General Description....................................................................................................................B-3
Recommended Processes...................................................................................................B-3
Operational Features and Controls......................................................................................B-3
Design Features and Advantages........................................................................................B-3
Welding Capability................................................................................................................B-4
Limitations............................................................................................................................B-4
Controls and Settings.................................................................................................................B-5
Upper Case Front Controls..................................................................................................B-5
Lower Case Front Controls................................................................................................B-11
Hand and Foot Amptrol™ Operation.................................................................................B-13
Welding Operation ....................................................................................................................B-15
Initial Start-up.....................................................................................................................B-15
Stick Welding ....................................................................................................................B-15
TIG Welding Guidelines......................................................................................................B-15
TIG Welding Sequence of Operation (2-Step Mode).........................................................B-20
TIG Welding Sequence of Operation (4-Step Mode).........................................................B-20
Overload Protection..................................................................................................................B-21
Auxiliary Power .........................................................................................................................B-21
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B-2
B-2
OPERATION
OPERATING INSTRUCTIONS
Read and understand this entire section of operating
instructions before operating the machine.
SAFETY INSTRUCTIONS
WARNING
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts or
electrodes with your skin or wet cloth-
ing.
• Insulate yourself from the work and ground.
• Always wear dry insulating gloves.
FUMES AND GASES can be
dangerous.
• Keep your head out of fumes.
• Use ventilation or exhaust to remove
fumes from breathing zone.
WELDING SPARKS can cause
fire or explosion.
• Keep flammable material away.
• Do not weld on containers that have held com-
bustibles.
ARC RAYS can burn.
• Wear eye, ear, and body protection.
Observe additional Safety Guidelines detailed in
the beginning of this manual.
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B-3
B-3
OPERATION
DESIGN FEATURES AND ADVANTAGES
GENERAL DESCRIPTION
• Designed to NEMA EW-1 and International IEC-974
Standards.
The Square Wave TIG 355 is a constant current, single
range square wave AC/DC TIG (GTAW) arc welding
power source with built-in high frequency stabilization.
It also has stick (SMAW) capability. The Square Wave
TIG 355 gives the operator full control of the welding
current plus the ability to preset weld and start cur-
rents. Preflow and postflow timers are included for
shielding gas and cooling water control. Altogether
the many features of the machine allow part or all of a
weld cycle to be preset or "programmed," which sim-
plifies the TIG welding process.
• Single output range of 2-400 amps covers the
majority of TIG welding applications.
• Solid State Output Contactor: no noise, no parts to
wear.
• Digital Ammeter and Voltmeter for precise readings
from 2-400 amps welding.
• Welding current limit can be preset from 2-400
amps and is displayed on the ammeter when not
welding.
The Square Wave TIG 355 includes advanced features
such as Auto-Balance™ 2-Step/4-Step Arc Start
Switch Operation, start controls, crater controls, spot
timer, and status LEDs. Preflow and postflow timers
allow control of shielding gas and cooling water.
• Auto Balance™ circuitry automatically provides the
proper amount of cleaning and penetration when
AC TIG welding. Manual AC wave balance adjust-
ment is also possible.
• 2-Step/4-Step Arc Start switch capability.
RECOMMENDED PROCESSES
• Spot control for 2-Step Arc Start switch mode.
The Square Wave TIG 355 is recommended for TIG
(GTAW) and stick (SMAW) welding processes within its
output capability of 2 to 400 amps on both AC and DC
polarity. It is compatible with all Magnum TIG acces-
sories as well as many industry standard TIG torches,
hoses, and water coolers. (See the Accessories sec-
tion of this manual.)
• TIG Pulser with On/Off selection, and Pulses Per
Second adjustment. Background current and duty
cycle are automatically adjusted according to the
peak welding current.
• Crater Fill control for current fade-out at the end of
a weld.
• Adjustable preflow time from 0 to 10 seconds.
Preflow time is eliminated if welding restarts during
gas afterflow of previous weld. This avoids unnec-
essary delays when making repeated welds.
OPERATIONAL FEATURES AND
CONTROLS
The following operational controls are standard on the
Square Wave TIG 355: Local/Remote current control
switch, Stick/TIG mode selection switch, TIG 2-
Step/TIG 4-Step mode selection switch, High
Frequency Continuous/Start/Off switch, Peak Current
control, Volts/Amps switch for the digital ammeter
reading, AC Wave Balance control, Afterflow timer for
shielding gas and water flow, Arc Force current control
for stick welding, Preflow timer for shielding gas and
water flow, Spot Time Controls, Start current/time
controls, Pulse controls (pulses per second, back-
ground % peak current, pulse % on), and Crater Fill
controls (fade-out, % peak current).
• Adjustable afterflow time control.
• Locate/Remote current selection.
• Stick/TIG selection.
• Arc Force control of added current when electrode
shorts to the work in stick mode.
• Continuous/Start/Off High Frequency selection.
• DC+/AC/DC- Polarity switch.
• Power Factor Correction for lower input currents
and smaller input wire sizes.
• Remote Receptacle for Amptrol™ or Arc Start
switch.
The following additional features are also standard:
Digital ammeter selectable for either volts or amps;
Status Indicator LEDs for gas and water, high frequen-
cy, arc established, start, peak, background, crater fill.
• Low Voltage Arc Start switch circuit (24 VAC) for
maximum operator safety.
• Gas and optional water valves: Inlet and outlet fit-
tings conform to Compressed Gas Association
(CGA) standards.
• Built-In High Frequency Generator.
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B-4
B-4
OPERATION
• 115 Volt receptacle with 15 amp circuit breaker.
WELDING CAPABILITY
• 220 Volt European (Schuko) type receptacle with 2
amp circuit breaker for water coolers (50/60Hz
machines only).
The Square Wave TIG 355 is NEMA Class II (40) Power
Source rated 350 amps at 34 volts, 40% duty cycle.
The duty cycle is based upon a 10 minute time period.
(For 40% duty cycle, it is 4 minutes on and 6 minutes
off.) The overload capacity is 375 amps at 35 volts,
30% duty cycle.
• Excellent arc starting and stability up through 400
amps.
• High resistance to AC arc rectification.
The “Lincoln Plus” rating of 300 amps at 40 volts pro-
vides additional voltage to overcome voltage drops in
long cables when stick welding at high currents.
• No tungsten spitting within current range of elec-
trode.
• Compact size, requires only a 22.25 in x 26 in (565
mm 660 mm) footprint.
LIMITATIONS
• Strain relief holes in base for welding cables, gas
and water hoses and control cables.
• The Square Wave TIG 355 is not recommended for
arc gouging. The machine's output capacity is too
limited.
• Easy access for input connections. Connections
are simple strip and clamp of input wires (no lugs
required).
• The Square Wave TIG 355 is not recommended for
AC TIG welding with high concentrations of helium
shielding gas. Starting problems and arc rectifica-
tion may occur.
• Low fan noise at idle.
• Modular construction for easy servicing.
• The Square Wave TIG 355 is not recommended for
pipe thawing.
• Unused controls are automatically locked out to
simplify setup. Examples: the AC Wave Balance
control has no effect in DC; the High Frequency and
gas and water valves do not operate in Stick mode;
TIG Pulser is locked out in the Stick mode.
• Recessed panels protect controls, output terminals,
gas and water fittings.
• Large safety margins and protective circuits protect
rectifiers from transient voltages and high currents.
• Line voltage compensated.
• Thermostatically protected.
• Electronic over current protection.
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B-5
B-5
OPERATION
CONTROLS AND SETTINGS
UPPER CASE FRONT CONTROLS
Controls on the upper case front control panel are
used for manual TIG and stick welding. Their func-
tions are described below. Some controls are active in
both TIG and stick welding, while others are active in
TIG only. Refer to Figure B.1 for control locations.
FIGURE B.1 – UPPER CASE FRONT CONTROLS
1
2
10
4
5
3
6
7
8
9
11
17
15
16
14
13
12
1. REMOTE/LOCAL CURRENT CONTROL SWITCH
2. MODE SWITCH (STICK/TIG)
7. VOLTS/AMPS METER SWITCH
8. AC WAVE BALANCE
12. PREFLOW TIMER
13. SPOT CONTROLS
3. 2-STEP/4-STEP SWITCH
4. HIGH FREQUENCY SWITCH
5. DIGITAL VOLTMETER/AMMETER
6. PEAK CURRENT CONTROL
9. AUTO-BALANCE™ LED
10. AFTERFLOW
11. STICK ARC FORCE
14. START CONTROLS
15. PULSE CONTROLS
16. CRATER FILL CONTROLS
17. STATUS INDICATOR LEDs
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B-6
B-6
OPERATION
NOTE: If the Crater Fill switch (Item 16) is ON,
welding will continue after the Arc Start switch is
pressed and released the second time. (See
Crater Fill Controls.)
UPPER CASE FRONT CONTROL PANEL
The upper case front panel controls are used for man-
ual TIG and stick welding.
1. CURRENT CONTROL SWITCH
NOTE: If the arc goes out while welding in the 4-
Step mode, the machine will try to re-establish an
arc for a period of two seconds. The output con-
tactor will remain closed, and the High Frequency,
if in the Start Only or continuous mode, will be
activated. If an arc does not re-establish within
two seconds, the weld cycle is automatically
ended.
A two-position toggle switch:
LOCAL (PANEL): Current is controlled by the
machine settings; remote Amptrol has no affect
on current.
REMOTE: Current is controlled by a remote
Amptrol up to the current set on the machine.
4. HIGH FREQUENCY SWITCH
2. MODE SWITCH
A three-position toggle switch: (Locked out in
STICK mode).
A two-position toggle switch:
STICK: For stick electrode welding (SMAW), this
position makes the Stick Arc Force control active.
This switch locks out high frequency, the gas and
water valves, and the AC Wave Balance control.
The STICK position also locks out the Spot Time,
Start Time and Crater Fill controls. The Pulse con-
trols are locked out except when an Arc Start
switch connected to the Remote receptacle is
closed.
CONTINUOUS: High frequency will come on after
the gas Preflow time and remain on until the weld
is stopped.
START : High Frequency will come on for 1-2 sec-
onds after an arc is established, then go off.
(When AC TIG welding, the high frequency will
stay on until after the Start period and come on
again during the Crater Fill period.)
TIG: For TIG welding (GTAW), this position locks
out the Stick Arc Force control. It makes all other
controls active. To start and stop the welding
sequence and to get output current, an Amptrol or
Arc Start switch must be used when this switch is
in the TIG position.
OFF: No high frequency.
5. DIGITAL VOLTMETER/AMMETER
Displays the output voltage of the welder when the
VOLTS/AMPS switch (Item 7) is held in the
“VOLTS” position.
3. 2-STEP/4-STEP SWITCH
When the VOLTS/AMPS SWITCH IS IN THE
“AMPS” position, this display functions as an
ammeter.
A two-position toggle switch: (Locked out in the
STICK mode.)
When you are not welding, the ammeter displays
the value preset by the Peak Current control.
2-STEP: For use with an Arc Start switch or an
Amptrol remote current control. The Arc Start
switch must be held down during the entire weld
cycle. Pressing the Arc Start switch starts the
Preflow cycle, and releasing the switch ends the
weld cycle.
When you are not welding and the Start Current
Display pushbutton is pressed, the ammeter will
display the preset Start (Item 14). (See Start
Controls)
NOTE: If the Crater Fill switch (Item 16) is ON,
welding will continue after the Arc Start switch is
released. (See Crater Fill controls.)
NOTE: The ammeter display is an indicator of the
preset current. Actual welding current will be
slightly different.
4-STEP: For use with an Arc Start switch only. The
Arc Start switch must be pressed and released to
start the weld cycle. Pressing and releasing the
Arc Start switch a second time ends the weld
cycle. This eliminates the need to continuously
hold down the Arc Start switch during a weld. If
the Preflow timer (Item 12) is being used, the Arc
Start switch must be held down during the Preflow
time. The Arc switch can be released once an arc
is established.
While you are welding, the ammeter displays the
actual welding current. The ammeter is accurate
within ±3% of its reading or ±2 amps, whichever is
greatest. The ammeter displays RMS current.
(RMS current is the actual “heating value” of the
arc.) NOTE: Some types of ammeters will not
accurately read true RMS currents, particularly
when AC TIG welding aluminum. AC only amme-
ters may read as much as 40% low when measur-
ing AC TIG welding currents.
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B-7
B-7
OPERATION
6. PEAK CURRENT CONTROL
.
CAUTION
Presets the maximum welding current the
machine will produce, from 2 through 400 amps.
The preset current is displayed on the digital
ammeter when you are not welding.
Use only the amount of “cleaning” required. Greater
amounts of positive current will heat the tungsten
more and possibly cause it to melt or “spit.” Also, the
arc is usually more flared and less stable with more
positive “cleaning” current.
NOTE: The ammeter display is an indicator of the
preset current. Actual welding current will be
slightly different.
If you use an Amptrol, it will control the current
from 2 amps up to the current preset by the Peak
Current control. See the section, “Hand and Foot
Amptrol Operation” for proper use of hand and
foot Amptrols.
PENETRATION (Above “3” on the dial): Provides
more negative current than positive current. The
“cleaning” effect will be reduced, but the arc plas-
ma will be more concentrated and more easily
directed to where the heat is needed. The
reduced amount of positive current allows the
tungsten to run cooler at a given current than
when set balanced.
If pulsing, the peak current is the current set and
controlled by the Peak Current control (Item 6) and
the Amptrol.
7. VOLTS/AMPS SWITCH
In general, use just enough “cleaning” to remove
oxides and to give good wetting of the puddle.
A two-position, spring-loaded toggle switch for
selecting either arc voltage or welding current/pre-
set current to be displayed on the digital meter.
9. AUTO BALANCE™ LED
Illuminates only when the Auto Balance function is
active. The welder must be in the AC TIG mode,
with the AC Wave Balance control fully clockwise.
To read the arc voltage, you must hold the switch
in the “Volts” position. This spring-loaded switch
always returns to the “AMPS” position when
released.
10. AFTERFLOW
This control adjusts the amount of time the gas
and water valves stay open after the end of a weld.
Minimum time is approximately 5 seconds; maxi-
mum is approximately 55 seconds. Use enough
Afterflow time to protect the hot tungsten with gas
shielding until it cools. Too short of a time will
cause the tungsten to oxidize and become conta-
minated. When in doubt, set a longer time, then
reduce it to a time that still gives good protection.
8. AC WAVE BALANCE
This control is active only in AC TIG mode. It con-
trols the amounts of positive and negative current
in the AC output. It has no effect on stick or DC
TIG welding.
AUTO BALANCE™: This setting provides automat-
ic adjustment of the AC wave balance, and it is the
preferred balance setting for most welding condi-
tions. This setting gives the ideal amount of clean-
ing and penetration, based on the welding current
output. When the control is set to the Auto
Balance position, the Auto Balance LED (Item 9)
will light. This feature operates only in the AC TIG
mode.
PREFLOW
All machines have an adjustable Preflow time.
If a new weld is started during the Afterflow time of
a previous weld, the Preflow time is bypassed,
since gas shielding is already present. This allows
new welds to start immediately, with no preflow
delay.
For those procedures when manual adjustment of
the Wave Balance control is necessary, use the
following as a guide:
11. ARC FORCE
BALANCED: The amounts of positive and negative
are the same.
This control is active only in Stick mode. It con-
trols the amount of current added to the welding
current when the electrode shorts to the work.
CLEANING (Below “3” on the dial): Provides more
positive current than negative current. Since the
positive current produces the “cleaning” or oxide
removal on aluminum, this setting is used for
heavily oxidized aluminum.
At Minimum, no extra short circuit current is
added. The arc will be softer and will have less
spatter but may be more prone to sticking.
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B-8
B-8
OPERATION
At Maximum, the arc will be more forceful and less
prone to sticking but will produce more spatter.
Press and hold in this pushbutton to display the
Start Current preset by the Start Current control.
(The Volts/Amps switch (Item 7) must be in the
“AMPS” position to read preset current.)
12. PREFLOW
This control adjusts the amount of time the gas
and water valves are open before the arc starts. It
is adjustable from 0 to 10 seconds.
Start Current Control
Locked out if the Start switch is off.
The Preflow time occurs only if the valves were
closed (no gas flow) when the Arc Start switch or
Amptrol was pressed. If a new weld is started
while the gas valve is still on during the Afterflow
time of a previous weld, the Preflow time is
bypassed since gas shielding is already present.
This allows new welds to start immediately with no
preflow delay.
Presets the current that will be provided at the
start of the weld. The current can be preset from
2 to 400 amps. The position of the amptrol has no
effect on the initial current. The present Start
Current is displayed on the Ammeter when the
pushbutton is pressed before welding.
A “hot” start is used to quickly heat the tungsten
and work, usually on DC TIG welding. Set the
Start Current higher than what the welding current
will be. After the time is set on the Start Time con-
trol, the current will step down to the current set
and controlled by the Peak Current control (Item 6)
and the Amptrol.
Note that since the arc cannot start during the
Preflow time, a long Preflow setting can cause
complaints about arc starting. In general, a
Preflow time of 0.5 seconds is satisfactory for
most applications.
13. SPOT CONTROLS
A “soft” start is used to preheat the tungsten and
work, usually on AC TIG welding. Set the Start
Current lower than what the welding current will
be. The arc will establish at the Start Current and
then ramp up to the current set and controlled by
the Peak Current control (Item 6) and the Amptrol.
The time to get up to welding current is set by the
Start Time control. During the ramp up, the
Amptrol will affect the current that the ramp is
going toward and therefore the rate at which the
current increases.
Spot Switch — A two-position toggle switch:
Recommended for use in the 2-step Arc Start
Switch mode only.
ON: Spot Time control is active. Once the arc is
established, the Spot time begins. At the end of
the Spot time (or if the Arc Start switch/Amptrol is
released sooner), the arc stops. (If Crater Fill [Item
16] is on, downslope begins.)
OFF: Locks out the Spot Time control.
Start Time Control
Spot Time Control: Not active if the Spot switch
is off. Adjusts weld time from 0.1 to 5 seconds.
Weld time is the time from when the arc is fully
established until the arc is turned off (or when
Crater Fill downslope is started). The Arc Start
switch or Amptrol must be held down during the
Spot time; if it is released before the end of the
Spot time, the arc will be turned off (or Crater Fill
started).
Locked out if the Start switch is off. Adjusts the
Start Time from approximately 0.1 to 10 seconds.
15. PULSE CONTROLS
Pulse Switch — A two-position toggle switch:
ON: Pulsing will begin as soon as an arc is estab-
lished and will continue until the weld is complet-
ed. If you are using Start Controls, pulsing begins
after the Start Current. If you are using Crater Fill,
pulsing will continue during the downslope period.
14. START CONTROLS
Start Switch — A two-position toggle switch:
OFF: Locks out Pulse controls.
ON: Start Current control is active. At the begin-
ning of the weld, current will be the value preset by
the Start Current control. Th position of the
Amptrol has no effect on this current.
Pulses per Second Control — Controls the num-
ber of pulses per second from approximately 0.1
to 10 pps. 0.1 pulses per second is slow pulsing
(one pulse every 10 seconds); 10 pulses per sec-
ond is fast pulsing.
OFF: Locks out Start Current and Time controls.
Start Current Display Pushbutton
Background % Peak Current Control —
Controls the background (low pulse) current from
zero to 100% of the peak current set and con-
trolled by the Peak Current control (Item 6) and the
Amptrol.
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B-9
B-9
OPERATION
Example: The Peak Current control is preset at 50
OFF: Locks out Crater Fill controls.
amps and the Amptrol is partially down, giving a
peak current of 30 amps. If the Background
Current control is set at 50%, the Background (low
pulse) current will be 15 amps.
Fade-out Control — Controls how slowly the cur-
rent fades out. The FAST setting will cause current
to ramp down from the welding current toward 2
amps in approximately 1/2 second; the SLOW set-
ting, in approximately 20 seconds. The time for
downslope to the Crater Fill Current level depends
on the difference between the weld current and
the Crater Fill Current.
The Amptrol raises and lowers the Peak current.
Since Background current is always a percentage
of Peak current, the Amptrol also raises and low-
ers the Background current.
Pulse % On — Controls the percentage of the
pulse cycle that is at the Peak current.
Crater Fill % Peak Current Control — Controls
the final Crater Fill current from zero to 100% of
the weld current preset on the Peak Current con-
trol.
Example: You are pulsing at 1 Pulse per second
with a 30% Pulse % On setting. The welding cur-
rent would be at the Peak current for 0.3 seconds
and at the Background current for the remainder
of the cycle, 0.7 seconds.
Example: WIth a Crater Fill % Current setting of
20% and a weld current preset at 100 amps, the
current will fade from 100 amps to 20 amps and
then dwell at 20 amps for about 1-1/2 seconds
before the arc goes out.
16. CRATER FILL CONTROLS
Use the Crater Fill controls to automatically control
current fade-out at the end of a weld. LOCAL cur-
rent control (Item 1) MUST be used when Crater
Fill is used.
The final Crater Fill current dwell time is approxi-
mately 1-1/2 seconds, regardless of Crater Fill
control settings.
17. STATUS INDICATOR LEDs — Seven Light
Emitting Diodes (LEDs) which light when their
function is active.
Crater Fill Switch — A two-position toggle
switch.
ON: Crater Fill Fade-out will begin when the Arc
Start Switch or Amptrol is released (2-Step mode)
or pressed and released a second time (4-Step
mode). If used with Spot Time (item 13), Crater Fill
begins at the end of the Spot Time. The current
control (item 1) switch must be in LOCAL when
using Crater Fill.
• GAS & WATER LED is on when the solenoid
valves are open, from the beginning of Preflow
to the end of Afterflow.
• HIGH FREQUENCY LED is on when the high
frequency circuit is on.
FIGURE B.2 – STATUS INDICATOR LIGHT SEQUENCE
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B-10
B-10
OPERATION
• ARC ESTABLISHED LED goes on when the arc
NOTE: An LED will light in response to the control cir-
cuit command, even if other components do not work.
For example, if the gas supply is turned off or the gas
solenoid valve malfunctions or the fuse is blown, the
gas will not flow even though the Gas and Water LED
lights up. Another example is the High Frequency LED
which can light, yet there will not be high frequency
due to a blown fuse or defective high frequency circuit
or spark gaps set too large.
is fully established and goes out if the arc goes
out.
• START LED is on from the time the arc is estab-
lished until current begins to go up (soft start) or
down (hot start). Note that the Start LED is off
during upslope if a soft start is used.
• PEAK LED goes on after the Start period. If the
Pulse switch is on, the Peak LED goes off dur-
ing the Background periods. The Peak LED and
Background LED will alternate when pulsing.
The Status Indicator LEDs are useful for understanding
which functions are active during a weld sequence
and for how long. They are useful for setting times of
the controls on the Function Panel. See Figure B.2.
• BACKGROUND LED is on during the
Background (low pulse) period of pulsing.
The Status Indicator LED circuit board includes a
receptacle for plugging in the circuit board included
with the Optional Interface Kit.
• CRATER FILL LED is on during the Fade-Out
downslope and final current periods.
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B-11
B-11
OPERATION
LOWER CASE FRONT CONTROLS
Refer to Figure B.3 for the location of the following controls.
FIGURE B.3 – LOWER CASE FRONTCONTROLS
1
2
3
5
4
9
6
8
7
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B-12
B-12
OPERATION
1. POWER ON/OFF — A momentary start/stop
pushbutton, which controls the input contactor. If
the input power supply goes off or if the thermo-
stat in the welder trips, the start pushbutton must
be pressed to restart the welder.
6. REMOTE RECEPTACLE — A six-pin circular con-
nector for an Arc Start switch or an Amptrol
remote current control.
7. 115 VOLT RECEPTACLE AND CIRCUIT BREAK-
ER — A duplex 15 amp grounded NEMA 5-15R
receptacle and 15 amp circuit breaker. Fifteen
amps of 115 volt AC power is available continu-
ously whenever the power is on. The circuit
breaker button will pop out if it trips. Reset by
pushing it in after the circuit breaker cools and the
overload has been removed.
2. PILOT LIGHT — Indicates when the input contac-
tor is energized (power is on).
CAUTION
Do not switch polarity under load.
8. HIGH FREQUENCY INTENSITY CONTROL AND
SPARK GAP — This control changes the high fre-
quency intensity. Use the lowest intensity which
still gives good arc starting to minimize Radio
Frequency Interference (RFI). The spark gap is set
at the factory to the normal setting marked on the
cover plate. Instructions for larger or smaller gap
settings are also on the cover plate.
3. POLARITY SWITCH — Selects DC-/AC/DC+
4. FUSE F1 — 0.5 amp control circuit fuse protects
the control transformer from overloads. Input
overvoltage protection circuitry will blow this fuse
to protect electronic components if the input volt-
age to the welder is too high (more than 40% over
rated voltage). If this fuse blows, the digital meters
will not light and the input contactor will not latch
when the Power On/Off Start pushbutton is
pressed and released.
9. GAS AND OPTIONAL WATER VALVES —
Solenoid valves that open at the beginning of the
Preflow time and close at the end of the Afterflow
time.
The gas valve inlet and outlet are standard 5/18-18
right-hand female fittings. The water valve inlet
and outlet are standard 5/8-18 left-hand female fit-
tings. The fittings conform to CGA (Compressed
Gas Association) standards. Use a water line
strainer to prevent particles from jamming the
water valve.
5. FUSE F2 — 1.5 amp gas, water, and high fre-
quency fuse protects the circuitry that drives the
gas and water valves and the high frequency sup-
ply transformer. If this fuse blows, the valves and
high frequency will not work. However, the LEDs
for Gas and Water and High Frequency will still
light.
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B-13
B-13
OPERATION
HAND AND FOOT AMPTROL OPERATION
Both the Hand and Foot Amptrol (optional kits K870 or
K812) work in a similar manner. They are meant to be
used for remote current control when Remote Current
control is selected. The TIG 2-Step mode must be
selected when using an Amptrol for remote current
control. As explained below, Amptrols can also be
used as arc start switches if Local Current control is
selected.
A similar situation occurs when the Start controls are
used. For example, a 3/32” (2.4 mm) tungsten is again
used for welding DC- up to 200 amps (preset on the
ammeter). A Start current of 50 amps is set on the
Start Level control. When you depress the Amptrol,
the start circuitry sets the output current to 50 amps.
If the Amptrol is kept near the minimum position, at the
end of the start period the output current will drop to 2
amps, causing the arc to go out in most cases.
Depress the Amptrol at least 1/4 of the way down, or
to around 70 amps, so that the tungsten remains lit
when the start period ends.
For simplicity, the following explanation will refer only
to “Amptrols,” meaning both Foot and Hand models.
The term “minimum” refers to a Foot pedal in the “up”
position, as it would be with no foot pressure, or a
Hand Amptrol in the relaxed position, with no thumb
pressure. “Maximum” refers to a fully depressed Foot
Amptrol, or a fully extended Hand Amptrol.
The same holds true for a “hot” start, or one in which
the Start current is set to a current higher than the cur-
rent preset on the ammeter. Again, at the end of the
start period, the Amptrol must be depressed far
enough so that the machine output will be high
enough to keep the arc lit.
The Amptrol is capable of controlling the output cur-
rent from 2 amps to whatever current is preset on the
ammeter. For example, if the ammeter is preset for
200 amps and the Current Control switch is in the
Remote position, the Amptrol, when depressed just
past its minimum position, will cause the Square Wave
TIG 355 to weld at 2 amps. At the Amptrol’s maximum
position, the output would be near 200 amps. See
Figure B.4.
The best technique when using the start controls and
an Amptrol is to press the Amptrol to maximum at the
beginning of the weld, wait until the end of the start
period, and then back off on the amptrol only if the
current is too high.
If the Current Control switch is set to the Local posi-
tion, an Amptrol can be used as an arc start switch.
Depressing the amptrol just past minimum will cause
the Amptrol’s built-in arc start switch to close, and
backing off completely causes the built-in start switch
to open. The Amptrol will have no effect on the weld-
ing current when used as an arc start switch. See
Figure B.5.
CAUTION
Since the full output of the current setting is available
when the Amptrol is fully depressed, care must be
taken not to set a current which will exceed the current
carrying capacity of the tungsten. When in doubt, use
a lower current setting first, then increase.
It is important to note that, for many applications, the
tungsten will not start an arc at only 2 amps. To start
an arc reliably, it is important to depress the Amptrol
far enough so that the machine output current is near
the tungsten operating range. (See Table B.2 for rec-
ommended tungsten currents.) In the example above,
a 3/32” (2.4 mm) tungsten may be used on DC- to
weld near 200 amps. To start the weld, the operator
may have to depress the Amptrol approximately 1/4 of
the way down, or to nearly 70 amps, in order to start
the arc. Merely depressing the Amptrol to its 2 amp
minimum position will not start the arc.
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B-14
B-14
OPERATION
FIGURE B.4 – AMPTROLS USED WITH CURRENT CONTROL IN THE LOCAL POSITION
FIGURE B.5 – AMPTROLS USED WITH CURRENT CONTROL IN REMOTE POSITION
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B-15
B-15
OPERATION
Select STICK mode. (High Frequency switch has
no effect in STICK mode.)
WELDING OPERATION
INITIAL START-UP
4. Preset the current with the Current control and the
Ammeter.
Be sure the Square Wave TIG 355 has been installed
correctly with respect to location, high frequency pro-
tection, input power, and output connections.
5. Set the desired Arc Force. (See CONTROLS AND
SETTINGS, item 11, “Arc Force.”) (The Wave
Balance and Afterflow controls have no effect in
STICK mode.)
If you are TIG welding, connect a K870 or K812
Amptrol or a K814 Arc Start switch to the Remote
Receptacle. Check that the gas supply is on. Check
for the correct type and size of tungsten electrode, gas
cone size and torch size. If you are using a water
cooled torch, check that the water supply is on.
6. Turn the Start switch OFF, or set the START con-
trols for a hot start if needed. (See CONTROLS
AND SETTINGS, item 14, “Start Controls.”)
7. Strike an arc and weld. (There will be a buzzing
sound from the arc if you are AC welding, due to
the faster rate of current reversal of the Square
Wave.
Press the Start (green) Power pushbutton. The input
contactor will pull in, the pilot light will come on, the
meter displays will light up, and the fans will start. In
TIG mode, the gas and water valves will open for one
Afterflow period to purge the lines. The ammeter will
display the preset current (if there is no load on the
welder output terminals). The voltmeter will read zero
in TIG mode, or from 60 to 70 in STICK mode.
TIG WELDING GUIDELINES
Recommended tungsten electrode sizes, stickouts,
currents, cup or nozzle sizes and gas flow are shown
in Table B.2. SINCE TIG APPLICATIONS CAN VARY,
THIS TABLE IS INTENDED AS A GUIDE ONLY.
Select the Electrode Polarity needed (DC-/AC/DC+) .
Set the controls by going from left to right across the
top row and then the bottom row, choosing the correct
setting for each. Note that the bottom row of controls
includes on/off switches to easily lock out the controls
within blocks (Spot, Start, Pulse, or Crater Fill) without
changing the settings. Also, note that some of the
controls are automatically locked out internally if they
do not apply in STICK mode or do not apply in TIG
mode. This reduces the number of controls which
must be set. See Table B.1 for examples of the effects
of the Function controls on TIG welding.
Aluminum Welding: Set the Electrode Polarity switch
to AC, the High Frequency switch to CONTINUOUS,
and the Mode switch to TIG. Make all other control
settings to suit the size tungsten and current. In gen-
eral, pure or zirconiated tungsten electrode is best for
aluminum and should have a “balled” end not exceed-
ing the diameter of the tungsten. A buzzing sound will
occur in the arc when AC TIG welding aluminum. We
recommend that you set the AC Wave Balance control
to the Auto Balance position. For more information
see CONTROLS AND SETTINGS, item 8, “AC Wave
Balance.”
STICK WELDING
Stainless or Mild Steel Welding: Set the Electrode
Polarity switch to DC-, the High Frequency switch to
START, and the Mode switch to TIG. In general, 1% or
2% thoriated tungsten electrode is best for stainless or
mild steel and should have the end ground to a point.
If there is difficulty starting the arc, the tunsten may be
contaminated, or it may be too large to get up to oper-
ating temperature.
1. Remove the Amptrol or Arc Start switch from the
Remote Receptacle.
2. Turn the welder on. The pilot light on the front
panel indicates when the power is on.
3. Select LOCAL current control;
Note: Starting difficulties may often be due to not
pressing the Amptrol far enough. When the
Amptrol is just “cracked,” the minimum current
(2 amps) is produced. Pressing the Amptrol
more at the start of the weld will often solve
starting problems.
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B-16
B-16
OPERATION
TABLE B.1
SPECIFIC EFFECTS OF CONTROLS
(illustrated in the 2-Step Mode for clarity)
EFFECT OF CONTROLS ON TIG WELDING
PRESET
CURRENT
LOCAL CURRENT CONTROL
ALL LOWER PANEL
SWITCHES OFF
AFTERFLOW
PRESET
CURRENT
REMOTE CURRENT CONTROL
ALL LOWER PANEL
SWITCHES OFF
REMOTE AMPTROL CONTROLS
FROM 2 AMPS UP TO
PRESET CURRENT
START TIME
START CURRENT
LOCAL OR REMOTE CURRENT CONTROL
START SWITCH ON
START CURRENT SET HIGHER THAN
PRESET CURRENT (HOT START)
START TIME: VARIABLE
PRESET
CURRENT
ALL OTHER PANEL SWITCHES OFF
REMOTE AMPTROL CONTROLS
FROM 2 AMPS UP TO
PRESET CURRENT
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B-17
B-17
OPERATION
EFFECT OF CONTROLS ON TIG WELDING
MAX START
TIME
LOCAL OR REMOTE CURRENT CONTROL
START SWITCH ON
PRESET
CURRENT
START CURRENT SET LOWER THAN
PRESET CURRENT (SOFT START)
START TIME: VARIABLE
ALL OTHER PANEL SWITCHES OFF
REMOTE AMPTROL CONTROLS
FROM 2 AMPS UP TO
PRESET CURRENT
LOCAL CURRENT CONTROL
CRATER FILL SWITCH ON
CRATER FILL % CURRENT VARIABLE
FADE-OUT VARIABLE
ALL OTHER LOWER PANEL SWITCHES
OFF
SLOW
FADE-OUT
FAST FADE-OUT
-3 SEC.
CRATER FILL TIME
LOCAL CURRENT CONTROL
START SWITCH ON
(SOFT START SHOWN; MAY HAVE HOT
START)
PRESET
CURRENT
CRATER FILL SWITCH ON
ALL OTHER PANEL SWITCHES OFF
START
CURRENT
CRATER FILL
% CURRENT
LOCAL OR REMOTE CURRENT CONTROL
PULSE SWITCH ON
PULSES PER SECOND
BACKGROUND % DUTY CYCLE
PULSE % ON
PRESET
CURRENT
(PEAK)
ALL OTHER LOWER PANEL SWITCHES
OFF
BACKGROUND
% CURRENT
REMOTE AMPTROL CONTROLS
FROM 2 AMPS UP TO
PRESET CURRENT
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B-18
B-18
OPERATION
EFFECT OF CONTROLS ON TIG WELDING
START TIME
START CURRENT
LOCAL CURRENT CONTROL
START SWITCH ON
(SHORT HOT START SHOWN)
PULSE SWITCH ON
PRESET
CURRENT
CRATER FILL SWITCH ON
(SLOW FADE-OUT SHOWN)
SPOT SWITCH OFF
BACKGROUND
% CURRENT
LOCAL OR REMOTE
SPOT SWITCH ON
ALL OTHER LOWER PANEL SWITCHES
OFF
SPOT TIME
SPOT TIME
(SPOT TIME IS CUT SHORT IF ARC
START SWITCH IS OPENED BEFORE
END OF SPOT TIME)
PRESET
CURRENT
REMOTE AMPTROL CONTROLS CURRENT
FROM 2 AMPS UP TO PRESET CURRENT
THE SPOT TIMER CAN BE USED TO TIME A PROGRAMMED SEQUENCE OF START AND/OR
PULSE UP TO 5 SECONDS LONG, OPTIONALLY FOLLOWED BY CRATER FILL. IF CRATER FILL
IS USED, FADE-OUT BEGINS AT THE END OF THE SPOT TIME.
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B-19
B-19
OPERATION
TABLE B.2
TYPICAL CURRENT RANGES(1) FOR TUNGSTEN ELECTRODES(2)
AC
Approximate Argon
Gas Flow Rate
C.F.H. (l/min)
Unbalanced Wave
Balanced Wave
DCEN (-)
DCEP (+)
Tungsten
1%, 2%
1%, 2%
Electrode
Diameter
in. (mm)
1%, 2%
Thoriated
Tungsten
1%, 2%
Thoriated
Tungsten
Thoriated
Tungsten
Tungsten Zirconated
Thoriated
Tungsten
Zirconiated
TIG Torch
Nozzle
Size
Pure
Pure
Tungsten
Stainless
Steel
(4), (5)
Aluminum
(3)
(3)
.010 (.25)
0.020 (.50)
0.040 (1.0)
2-15
5-20
15-80
2-15
5-15
10-60
2-15
5-20
15-80
2-15
10-20
20-30
—
5-20
20-60
3-8 (2-4)
5-10 (3-5)
5-10 (3-5)
3-8 (2-4)
5-10 (3-5)
5-10 (3-5)
4,5,6
3)
(
1/16
(1.6)
70-150
10-20
50-100
70-150
30-80
60-120
5-10 (3-5)
9-13 (4-6)
5,6
3/32
1/8
(2.4)
(3.2)
150-250
250-400
15-30
25-40
100-160
150-210
140-235
225-325
60-130
100-180
100-180
160-250
13-17 (6-8)
15-23 (7-11) 11-15 (5-7)
11-15 (5-7)
6,7,8
5/32
3/16
1/4
(4.0)
(4.8)
(6.4)
400-500
500-750
750-1000
40-55
55-80
80-125
200-275
250-350
325-450
300-400
400-500
500-630
100-240
190-300
250-400
200-320
290-390
340-525
21-25 (10-12) 13-17 (6-8)
23-27 (11-13) 18-22 (8-10)
28-32 (13-15) 23-27 (11-13)
8,10
(1) When used with argon gas. The current ranges shown must be reduced when using argon/helium or pure helium shielding gases.
(2) Tungsten electrodes are classified as follows by the American Welding Society (AWS):
Pure .................................EWP
1% Thoriated ..................EWTh-1
2% Thoriated ..................EWTh-2
Though not yet recognized by the AWS, Ceriated Tungsten is now widely accepted as a substitute for 2% Thoriated Tungsten in AC and DC applications.
(3) DCEP is not commonly used in these sizes.
(4) TIG torch nozzle “sizes” are in multiples of 1/16ths of an inch:
# 4 = 1/4 in.
# 5 = 5/16 in.
# 6 = 3/8 in.
# 7 = 7/16 in.
#8 = 1/2 in.
#10 = 5/8 in.
(6mm)
(8mm)
(10mm)
(11mm)
(12.5mm)
(16mm)
(5) TIG torch nozzles are typically made from alumina ceramic. Special applications may require lava nozzles, which are less prone to breakage, but cannot withstand high
temperatures and high duty cycles. Currents above 350 amps require metal nozzles on water cooled torches.
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B-20
B-20
OPERATION
hose and torch. After a time determined by the
Preflow control setting, the high frequency
becomes available to strike the arc.
TIG WELDING SEQUENCE OF
OPERATION (2-STEP MODE)
11. Hold the Arc Start Switch down or operate the
Amptrol until the weld is completed. Release the
Arc Start switch or the Amptrol to stop the arc.
When the Afterflow timer completes the cycle, the
gas and water valves close. To make another
weld, repeat steps 10 and 11.
WARNING
Do not leave stick electrode welding cable connected.
It will be electrically “hot” when TIG welding.
1. Connect an Amptrol or Arc Start switch to the
Remote Receptacle.
2. Turn the welder, water supply (if equipped) and
gas supply on. The pilot light on the front panel
indicates when the power is on.
TIG WELDING SEQUENCE OF
OPERATION (4-STEP MODE)
3. Select REMOTE or LOCAL current control
(REMOTE requires an Amptrol).
WARNING
Do not leave stick electrode welding cable connected.
It will be electrically “hot” when TIG welding.
Select TIG mode.
Select CONTINUOUS or START high frequency.
Select AC or DC- electrode polarity. See Table B.3
for recommended polarity settings.
1. Connect an Arc Start switch to the Remote
Receptacle.
2. Turn the welder, water supply (if so equipped) and
gas supply on. The pilot light on the front panel
indicates when the power is on.
TABLE B.3
RECOMMENDED SETTINGS FOR TIG WELDING
Electrode
Polarity
High Frequency
Switch
3. Select LOCAL current control. Select TIG mode.
Select CONTINUOUS or START high frequency.
Select AC or DC- electrode polarity (See Table
B.3 for recommended polarity settings).
Type of Welding
Stainless Steel
DC-
Start
Aluminum and
Magnesium
AC
Continuous
Start
4. Preset the maximum current with the Peak
Current control and the Ammeter.
Other Metals
DC-
5. (Arc Force Control has no effect in TIG mode.)
6. If in AC, set AC Wave Balance control. (See CON-
TROLS AND SETTINGS, item 8, “AC Wave
Balance. This control has no effect in DC.)
4. Preset the maximum current with the Current con-
trol and the Ammeter.
5. (Arc Force control has no effect in TIG mode.)
7. Set Afterflow time.
6. If in AC, set AC Wave Balance control. (See CON-
TROLS AND SETTINGS, item 8, “AC Wave
Balance.” This control has no effect in DC.)
8. Set Function Panel controls as needed. (See
CONTROLS AND SETTINGS, “Lower Case Front
Controls”)
7. Set Afterflow time.
9. Press the Arc Start switch and set the gas
flowmeter. The welder is now ready for welding.
8. Set Function Panel controls as needed. (See
CONTROLS AND SETTINGS.)
10. Position the tungsten electrode at the start of the
weld at a 65° to 75° angle with the horizontal so
that the electrode is approximately 1/8” (4 mm)
above the workpiece. Press the Arc Start switch.
This opens the gas and water valves to automati-
cally purge air from the hose and torch. After a
time determined by the Preflow control setting,
the high frequency becomes available to strike the
arc.
9. Press the Arc Start switch or Amptrol and set the
gas flowmeter. The welder is now ready for weld-
ing.
10. Position the tungsten electrode at the start of the
weld at a 65° to 75° angle with the horizontal so
that the electrode is approximately 1/8” (3.2 mm)
above the workpiece. Press the Arc Start switch
or operate the Amptrol. This opens the gas and
water valves to automatically purge air from the
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B-21
B-21
OPERATION
11. Hold the Arc Start switch down until an arc is
established. At this point, the Arc Start Switch
can be released, and the weld will continue.
Press and release the Arc Start switch a second
time to stop the arc. When the Afterflow timer
completes the cycle, the gas and water valves
close. To make another weld, repeat steps 10
and 11.
AUXILIARY POWER
ALL MACHINES
The Square Wave TIG 355 provides 15 amps of 115
volt AC power at a standard NEMA 5-15R receptacle,
located on the lower case back of the machine. This
circuit is protected from shorts and overloading by a
15 amp circuit breaker, located next to the receptacle.
The auxiliary circuit is intended for running water cool-
ers and small power tools, whose current draw is with-
in the 15 amp rating.
Note: Starting difficulties may often be due to not
pressing the Amptrol far enough. When the Amptrol is
just “cracked,” the minimum current (2 amps) is pro-
duced. Pressing the Amptrol more at the start of the
weld will often solve starting problems.
50/60Hz MACHINES
Square Wave TIG 355 machines rated for 50/60Hz
operation provide 2 amps of 220 volt AC power at a
continental European (Schuko) type receptacle, lo-
cated on the lower case back of the machine. This cir-
cuit is protected from shorts and overloading by a 2
amp circuit breaker, located above the receptacle.
The auxiliary circuit is intended for running water
coolers whose current draw is within the 2 amp rating
of the receptacle.
OVERLOAD PROTECTION
The Square Wave TIG 355 has thermostatic protection
from overloads, loss of cooling, and high ambient tem-
peratures. When the welder is subjected to an over-
load or loss of cooling, a thermostat will open.
If the secondary thermostat opens, the effect will be
the same as pushing the Stop power pushbutton: the
power will go off, the pilot light and meters will go out,
and the fans will stop. Pressing the Start power push-
button after the thermostat cools and resets will restart
the welder.
CAUTION
If the primary thermostat opens, the power will stay on
(pilot light and meters on and fans running), but no
more than 5 amps DC output current will be available.
This allows the fans to cool the machine. Depending
on the amount of welder overload, the thermostat
should reset within five minutes with the fan motors
running. When the primary thermostat cools and
resets, normal output current will be available.
Note that some types of equipment, especially pumps
and motors, have starting currents significantly higher
than their running currents. These higher starting cur-
rents may cause the circuit breaker to open. If this sit-
uation occurs, the user should avoid using the Square
Wave TIG 355 auxiliary for that equipment.
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Section C-1
Section C-1
TABLE OF CONTENTS
- ACCESSORIES -
Accessories...........................................................................................................................Section C
Options/Accessories...................................................................................................................C-2
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C-2
C-2
ACCESSORIES
OPTIONS/ACCESSORIES
The following options/accessories are available for
your Square Wave TIG 355 from your local Lincoln
Electric Distributor.
Solid State Relays (SSRs):
K847-DC – Can switch up to 40VDC, 2 amps
maximum load. Package of two.
Undercarriage (K841) – Includes a platform, wheels,
and brackets for supporting the welder and two gas
cylinders.
K847-AC – Can switch up to 130VAC, 2 amp
maximum load. Package of two.
Amptrol™ (K870 or K812) – Provides a remote cur-
rent control for most TIG welding applications. Model
K870 is a foot operated control; model 812 is hand
operated. Both models plug into the remote control
receptacle. A separate switch on the Amptrol starts
the welding sequence. When the Current Control
switch on the welder is set in the LOCAL position, the
Amptrol works as an arc start switch only; it does not
control current. (Current is controlled by the rheostat
on the front panel.) When the Current Control switch
on the welder is set to the REMOTE position, current
is controlled by the Amptrol, in a range from 2 amps up
to the current set on the control panel. For a more
detailed explanation of Amptrol operation, see the
Operation Section of this manual.
Pump Mounting Platform (K827) – Mounts on top of
the welder to provide a mounting surface suitable for
water recirculating pumps.
Arc Start Switch (K814) – Starts the welding
sequence if remote control for TIG welding is not
desired. Plugs into the Remote Receptacle. The
Current Control switch must be in the LOCAL position
when using the Arc Start switch; only a minimum cur-
rent (2 amp) is available in REMOTE. Includes 25 ft.
(7.6 m) cable.
Interface Kit (K846) – Mounts to the back of the LED
status PC board. Provides six isolated circuits that
can be closed to provide status indication when each
of the following functions is active: High Frequency,
Arc Established, Start, Pulse Peak, Pulse Background,
and Crater Fill. Each circuit occupies two positions on
a terminal strip and consists of a fuse, fuse holder, and
sockets for an industry standard, optically isolated
Solid State Relay (SSR) module (purchased separate-
ly, see below).
1Use of the Synergic 7 wire feeder requires appropriate input cable assembly, wire stand, and drive roll kit. Refer to Synergic 7 Operator’s
Manual for available options.
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Section D-1
Section D-1
TABLE OF CONTENTS
-MAINTENANCE-
Maintenance .........................................................................................................................Section D
Safety Precautions......................................................................................................................D-2
Input Filter Capacitor Discharge Procedure...............................................................................D-2
Routine and Periodic Maintenance ............................................................................................D-3
General Component Locations...................................................................................................D-4
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D-2
D-2
MAINTENANCE
SAFETY PRECAUTIONS
WARNING
• Only Qualified personnel should
perform this maintenance.
• Turn the input power OFF at the
disconnect switch or fuse box
before working on this equipment.
• Do not touch electrically hot parts.
INPUT POWER FACTOR
CAPACITOR DISCHARGE
PROCEDURE
This procedure ensures that the power factor capaci-
tors are discharged, for greater safety when you are
working on the Square Wave TIG 355 with INPUT
POWER REMOVED.
1. Remove input power to the machine.
2. With a 5/16" nut driver, remove the sheet metal
screws that hold the right case side in place.
Remove the right case side.
3. With a volt/ohmmeter, carefully check the voltage
across the input power factor capacitors. When
input power is removed, the voltage across each
capacitor should be zero. (Normally, the capaci-
tors discharge through the primary winding in the
main transformer.)
4. If capacitor voltage is zero, you may begin working
on the Square Wave TIG 355.
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D-3
D-3
MAINTENANCE
5. If any voltage is present, DISCHARGE EACH INDI-
VIDUAL CAPACITOR as follows:
2. Periodically blow out dust and dirt from the inside
of the machine with a low pressure air system. Be
sure to clean the following components thorough-
ly. See Figure D.2 for their location.
a. Obtain a 500 Ohm resistor. Grip the 500 ohm
resistor with insulated gloves and insulated
gripping pliers and hold the resistor across the
terminals on each capacitor for 20 seconds.
See Figure D.1.
• Main transformer
• Output terminals (located on case front)
• Polarity switch (located on case front)
• Rectifier assembly
• Control box assembly
• Spark gap assembly
b. With the volt/ohmmeter, recheck each capac-
itor for voltage.
6. After all the capacitors are discharged completely,
check for broken capacitor leads or an open pri-
mary winding on the main transformer, which
would have prevented the capacitors from dis-
charging normally.
• Protection PC board
3. Inspect the welder output terminals and control
cables for fraying, cuts, and bare spots.
4. Inspect the spark gap spacing at regular intervals.
To access the spark gap, remove the nameplate
located on the lower right section of the output
panel.
Maintain the gap marked on the
ROUTINE AND PERIODIC
MAINTENANCE
machine cover plate. Please note the following:
• If more intensity is needed than is available with
the "High Frequency" set to MAXIMUM,
increase the spark gap according to the inter-
vals on the cover plate. (To minimize RFI prob-
lems, use the smallest possible spark gap set-
ting that still provides good welding.)
WARNING
To avoid receiving a high frequency shock, keep elec-
trode holders, TIG torches and cable insulation in
good condition.
• Do not dress or refinish the spark gap contacts.
Replace the electrodes if the contact surfaces
become irregular or completely eroded.
1. Disconnect power supply lines to the machine
before performing periodic maintenance.
5. The fan motors have sealed ball bearings and
require no maintenance.
FIGURE D.1 – POWER FACTOR CAPACITOR DISCHARGE DETAILS
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D-4
D-4
MAINTENANCE
FIGURE D.2 – GENERAL COMPONENT LOCATIONS
1. OUTPUT RECTIFIER/SCR BRIDGE ASSEMBLY
2. INPUT CONTACTOR
3. RECONNECT PANEL
4. PILOT TRANSFORMER
5. FAN AND FAN MOTOR
6. INPUT POWER FACTOR CAPACITOR
7. MAIN TRANSFORMER
8. CHOKE
9. HIGH VOLTAGE TRANSFORMER
10. PC BOARDS (POWER, CONTROL)
11. CASE FRONT
2
1
3
4
5
6
7
8
9
10
11
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Section E-1
Section E-1
TABLE OF CONTENTS
-THEORY OF OPERATION SECTION-
Theory of Operation .............................................................................................................Section E
General Description ....................................................................................................................E-2
Input Power Circuit:
Input Voltage, Contactor, Reconnect Panel, Pilot Transformer, Control Transformer,
Power Factor Capacitors, and Main Transformer.......................................................................E-2
Output Rectification and Feedback Control...............................................................................E-3
High Voltage/High Frequency Circuit..........................................................................................E-4
DC Welding Output .....................................................................................................................E-5
AC Welding Output .....................................................................................................................E-6
SCR Operation............................................................................................................................E-7
Protective Circuits.......................................................................................................................E-8
Thermal Protection ...............................................................................................................E-8
Overload Protection..............................................................................................................E-8
FIGURE E.1 – SQUARE WAVE TIG BLOCK LOGIC DIAGRAM
HIGH FREQUENCY SPARK
ELECTRODE SENSE
UPPER
CONTROL
PANEL
LOWER
CONTROL
PANEL
PANEL
SWITCHES
DISPLAY
BOARD
STATUS
BOARD
SCR GATE COMMANDS
15VDC
ELECTRODE
SENSE
HIGH VOLTAGE
TRANSFORMER
CIRCUIT
115VAC
REMOTE
RECEPTACLE
FEED - THRU
BOARD
CONTROL
BOARD
POWER
BOARD
TRIGGER
REMOTE
COMMANDS
INTERLOCK
GAS/WATER
SOLENOIDS
115VAC
WATER/GAS
HI-FREQ/
COMMANDS
INTERLOCK
INTERLOCK
HI-FREQ AND GAS/WATER
115VAC -
SNUBBER
BOARD
FANS
115VAC
CONTROL TRANSFORMER
115VAC
RECEPTACLE
115VAC
DC-
INPUT
CONTACTOR
AC
AC
R
E
C
H
O
K
E
C
O
DC+
N
N
POWER
FACTOR
CAPACITORS
BY-PASS
BOARDS
WORK
E
C
POLARITY
SWITCH
T
SHUNT
START/
STOP
ELECTRODE
MAIN
TRANSFORMER
HI-FREQ
TRANSFORMER
PILOT
TRANSFORMER
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E-2
E-2
THEORY OF OPERATION
FIGURE E.2 – INPUT VOLTAGE, CONTACTOR, RECONNECT PANEL, PILOT TRANSFORMER,
CONTROL TRANSFORMER, POWER FACTOR CAPACITORS AND MAIN TRANSFORMER
HIGH FREQUENCY SPARK
ELECTRODE SENSE
UPPER
CONTROL
PANEL
LOWER
CONTROL
PANEL
PANEL
SWITCHES
DISPLAY
BOARD
STATUS
BOARD
SCR GATE COMMANDS
15VDC
ELECTRODE
SENSE
HIGH VOLTAGE
TRANSFORMER
CIRCUIT
115VAC
REMOTE
RECEPTACLE
FEED - THRU
BOARD
CONTROL
BOARD
POWER
BOARD
TRIGGER
REMOTE
COMMANDS
INTERLOCK
GAS/WATER
SOLENOIDS
115VAC
WATER/GAS
HI-FREQ/
COMMANDS
INTERLOCK
INTERLOCK
HI-FREQ AND GAS/WATER
115VAC -
SNUBBER
BOARD
FANS
115VAC
CONTROL TRANSFORMER
115VAC
RECEPTACLE
115VAC
DC-
INPUT
CONTACTOR
AC
AC
R
E
C
H
O
K
E
C
O
DC+
N
N
POWER
FACTOR
CAPACITORS
BY-PASS
BOARDS
WORK
E
C
POLARITY
SWITCH
T
SHUNT
START/
STOP
ELECTRODE
MAIN
TRANSFORMER
HI-FREQ
TRANSFORMER
PILOT
TRANSFORMER
A reconnect panel allows the user to configure the
pilot transformer, the power factor capacitors, and the
main transformer for the desired input voltage. This
AC input voltage is applied, through the input contac-
tor, to the primary of the main transformer. The power
factor correction capacitors are incorporated in the
primary circuit of the main transformer to help balance
the inductive nature of the TIG 355. The main trans-
former changes the high voltage, low current input
power to a low voltage, high current output.
GENERAL DESCRIPTION
The Square Wave TIG 355 is a constant current, single
range square wave AC/DC TIG (GTAW) arc welding
power source with built-in high frequency stabilization.
It also has stick (SMAW) capability. The Square Wave
TIG 355 gives the operator full control of the welding
current plus the ability to preset weld and start cur-
rents. Preflow and postflow timers are included for
shielding gas and cooling water control. Altogether
the many features of the machine allow part or all of a
weld cycle to be preset or “programmed,” which sim-
plifies the TIG welding process.
In addition, the main transformer also has an isolated
115VAC auxiliary winding that supplies power to oper-
ate the cooling fans and offers 15 amps of auxiliary
power at the 115VAC receptacle. This 115VAC is also
applied, through the feed-thru board, to the power
board for high voltage and gas/water solenoid opera-
tion.
INPUT POWER CIRCUIT
The desired single-phase input power is connected to
the TIG 355 through an input contactor located in the
rear of the machine. The input power is also con-
nected directly to the pilot transformer, which supplies
115VAC for the input contactor interlock and start/
stop circuits.
The control transformer primary is also powered by the
115VAC winding in the main transformer. The sec-
ondary voltages that are developed in the control
transformer supply power to the control and power
boards.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
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E-3
E-3
THEORY OF OPERATION
FIGURE E.3 – OUTPUT RECTIFICATION AND FEEDBACK CONTROL
HIGH FREQUENCY SPARK
ELECTRODE SENSE
UPPER
CONTROL
PANEL
LOWER
CONTROL
PANEL
PANEL
SWITCHES
DISPLAY
BOARD
STATUS
BOARD
SCR GATE COMMANDS
15VDC
ELECTRODE
SENSE
HIGH VOLTAGE
TRANSFORMER
CIRCUIT
115VAC
REMOTE
RECEPTACLE
FEED - THRU
BOARD
CONTROL
BOARD
POWER
BOARD
TRIGGER
REMOTE
COMMANDS
INTERLOCK
GAS/WATER
SOLENOIDS
115VAC
WATER/GAS
HI-FREQ/
COMMANDS
INTERLOCK
INTERLOCK
HI-FREQ AND GAS/WATER
115VAC -
SNUBBER
BOARD
FANS
115VAC
CONTROL TRANSFORMER
115VAC
RECEPTACLE
115VAC
DC-
INPUT
CONTACTOR
AC
AC
R
E
C
H
O
K
E
C
O
DC+
N
N
POWER
FACTOR
CAPACITORS
BY-PASS
BOARDS
WORK
E
C
POLARITY
SWITCH
T
SHUNT
START/
STOP
ELECTRODE
MAIN
TRANSFORMER
HI-FREQ
TRANSFORMER
PILOT
TRANSFORMER
OUTPUT RECTIFICATION AND
FEEDBACK CONTROL
The AC output from the main transformer secondary is
rectified and controlled through the SCR bridge.
Output current is sensed at the shunt as a low voltage
signal and fed back to the control board. The control
board compares the commands of the control panels,
panel switches, and/or remote control with the shunt
feedback signal and electrode sense lead. The appro-
priate SCR gate firing commands are created by the
control board and sent to the power board where the
gate firing pulses are generated and applied through
the snubber board to the SCR bridge. The control
board controls the firing of the SCRs, which controls
the output of the machine. See SCR Operation. The
control board also powers and commands the display
board and the status board.
The electrode sense, the remote control and the trig-
ger signals are applied through the feed – thru board
to the control board.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
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E-4
E-4
THEORY OF OPERATION
FIGURE E.4 – HIGH VOLTAGE/HIGH FREQUENCY CIRCUIT
HIGH FREQUENCY SPARK
ELECTRODE SENSE
UPPER
CONTROL
PANEL
LOWER
CONTROL
PANEL
PANEL
SWITCHES
DISPLAY
BOARD
STATUS
BOARD
SCR GATE COMMANDS
15VDC
ELECTRODE
SENSE
HIGH VOLTAGE
TRANSFORMER
CIRCUIT
115VAC
REMOTE
RECEPTACLE
FEED - THRU
BOARD
CONTROL
BOARD
POWER
BOARD
TRIGGER
REMOTE
COMMANDS
INTERLOCK
GAS/WATER
SOLENOIDS
115VAC
WATER/GAS
HI-FREQ/
COMMANDS
INTERLOCK
INTERLOCK
HI-FREQ AND GAS/WATER
115VAC -
SNUBBER
BOARD
FANS
115VAC
CONTROL TRANSFORMER
115VAC
RECEPTACLE
115VAC
DC-
INPUT
CONTACTOR
AC
AC
R
E
C
H
O
K
E
C
O
DC+
N
N
POWER
FACTOR
CAPACITORS
BY-PASS
BOARDS
WORK
E
C
POLARITY
SWITCH
T
SHUNT
START/
STOP
ELECTRODE
MAIN
TRANSFORMER
HI-FREQ
TRANSFORMER
PILOT
TRANSFORMER
HIGH VOLTAGE/
HIGH FREQUENCY CIRCUIT
The control board signals the power board to pass the
115VAC voltage through the feed – thru board to the
primary of the high voltage tarnsformer. The sec-
ondary of the high voltage transformer is coupled to a
spark gap generator and also to the high frequency
transformer. The high frequency transformer transfers
the high frequency “spark” to the electrode terminal.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
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E-5
E-5
THEORY OF OPERATION
FIGURE E.5 – DC WELDING OUTPUT CIRCUIT
HIGH FREQUENCY SPARK
ELECTRODE SENSE
UPPER
CONTROL
PANEL
LOWER
CONTROL
PANEL
PANEL
SWITCHES
DISPLAY
BOARD
STATUS
BOARD
SCR GATE COMMANDS
15VDC
ELECTRODE
SENSE
HIGH VOLTAGE
TRANSFORMER
CIRCUIT
115VAC
REMOTE
RECEPTACLE
FEED - THRU
TRIGGER
CONTROL
BOARD
POWER
BOARD
BOARD
REMOTE
COMMANDS
INTERLOCK
GAS/WATER
SOLENOIDS
115VAC
WATER/GAS
HI-FREQ/
COMMANDS
INTERLOCK
INTERLOCK
HI-FREQ AND GAS/WATER
115VAC -
SNUBBER
BOARD
FANS
115VAC
CONTROL TRANSFORMER
115VAC
RECEPTACLE
115VAC
DC-
INPUT
CONTACTOR
AC
AC
R
E
C
H
O
K
E
C
O
DC+
N
N
POWER
FACTOR
CAPACITORS
BY-PASS
BOARDS
WORK
E
C
POLARITY
SWITCH
T
SHUNT
START/
STOP
ELECTRODE
MAIN
TRANSFORMER
HI-FREQ
TRANSFORMER
PILOT
TRANSFORMER
DC WELDING OUTPUT
When the polarity switch is placed in either DC posi-
tion, the AC voltage from the main transformer sec-
ondary is applied to the SCR bridge. The SCR bridge
and choke circuits are connected in a conventional full
wave bridge and filter configuration, resulting in a con-
trolled DC output. Since the choke is in series with the
negative leg of the bridge and also in series with the
welding load, a filtered DC is applied to the machine
output terminals.
FIGURE E.5a – SCR BRIDGE AND CHOKE CONFIGURATION FOR DC WELDING
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
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E-6
E-6
THEORY OF OPERATION
FIGURE E.6 – AC WELDING OUTPUT CIRCUIT
HIGH FREQUENCY SPARK
ELECTRODE SENSE
UPPER
CONTROL
PANEL
LOWER
CONTROL
PANEL
PANEL
SWITCHES
DISPLAY
BOARD
STATUS
BOARD
SCR GATE COMMANDS
15VDC
ELECTRODE
SENSE
HIGH VOLTAGE
TRANSFORMER
CIRCUIT
115VAC
REMOTE
RECEPTACLE
FEED - THRU
TRIGGER
CONTROL
BOARD
POWER
BOARD
BOARD
REMOTE
COMMANDS
INTERLOCK
GAS/WATER
SOLENOIDS
115VAC
WATER/GAS
HI-FREQ/
COMMANDS
INTERLOCK
INTERLOCK
HI-FREQ AND GAS/WATER
115VAC -
SNUBBER
BOARD
FANS
115VAC
CONTROL TRANSFORMER
115VAC
RECEPTACLE
115VAC
DC-
INPUT
CONTACTOR
AC
AC
R
E
C
H
O
K
E
C
O
DC+
N
N
POWER
FACTOR
CAPACITORS
BY-PASS
BOARDS
WORK
E
C
POLARITY
SWITCH
T
SHUNT
START/
STOP
ELECTRODE
MAIN
TRANSFORMER
HI-FREQ
TRANSFORMER
PILOT
TRANSFORMER
AC WELDING OUTPUT
Rotating the polarity switch to the AC position
changes the welding power circuit. One lead (X2) of
the main transformer secondary is connected to the
machine output work terminal. The other secondary
lead (X1) is connected to one of the AC connections
on the SCR bridge. The electrode terminal is con-
nected to the other AC side of the bridge. The choke
is now electrically across the negative and positive
SCR bridge connections. With the ability of the choke
to store energy and the SCRs to turn on at the appro-
priate times, an AC square wave is developed and
applied to the output terminals.
FIGURE E.6a – SCR BRIDGE AND CHOKE CONFIGURATION FOR AC WELDING
X1
X2
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
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E-7
E-7
THEORY OF OPERATION
FIGURE E.7 – SCR OPERATION
SCR OPERATION
A silicon controlled rectifier (SCR) is a three-terminal
device used to control rather large currents to a load.
An SCR acts very much like a switch. When a gate
signal is applied to the SCR, it is turned ON and there
is current flow from anode to cathode. In the ON state
the SCR acts like a closed switch. When the SCR is
turned OFF, there is no current flow from anode to
cathode; thus the device acts like an open switch. As
the name suggests, the SCR is a rectifier, so it passes
current only during positive half cycles of the AC sup-
ply. The positive half cycle is the portion of the sine
wave in which the anode of the SCR is more positive
than the cathode.
An SCR is fired by a short burst of current into the
gate. This gate pulse must be more positive than the
cathode voltage. Since there is a standard PN junc-
tion between gate and cathode, the voltage between
these terminals must be slightly greater than 0.6V.
Once the SCR has fired it is not necessary to continue
the flow of gate current. As long as current continues
to flow from anode to cathode, the SCR will remain
ON. When the anode to cathode current drops below
a minimum value, called holding current, the SCR will
shut OFF. This normally occurs as the AC supply volt-
age passes through zero into the negative portion of
the sine wave. If the SCR is turned ON early in the
positive half cycle, the conduction time is longer,
resulting in greather SCR output. If the gate firing
occurs later in the cycle, the conduction time is less,
resulting in lower SCR output.
When an AC supply voltage is applied to the SCR, the
device spends a certain portion of the AC cycle time in
the ON state and the remainder of the time in the OFF
state. The amount of time spent in the ON state is
controlled by the gate.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
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E-8
E-8
THEORY OF OPERATION
PROTECTIVE CIRCUITS
Protective circuits are designed into the Square Wave
TIG 355 to sense trouble and shut down the machine
before the trouble damages the internal machine com-
ponents. Both thermal protection and current over-
load are included.
THERMAL PROTECTION
Thermostats protect the machine from excessive
operating temperatures. Excessive operating temper-
atures may be caused by a lack of cooling air or by
operating the machine beyond the duty cycle and out-
put rating. If excessive operating temperature should
occur, causing the secondary thermostat to open, the
input contactor will shut the machine off. If the prima-
ry thermostat opens, the machine will stay on (pilot
light, meters and fans running), but output current will
be limited to no more than 5 amps.
Once the machine cools sufficiently the thermostats
are self-resetting. If the thermostat shutdown is
caused by excessive output or duty cycle and the fan
is operating normally, the power may be left on, and
the reset should occur within a 15 minute period. If the
fan is not functioning properly or the air intake louvers
are obstructed, then the input power must be removed
and the fan problem or air obstruction corrected.
OVERLOAD PROTECTION
The machine is electronically protected from produc-
ing excessively high output currents. Should the out-
put current exceed approximately 400 amps, an elec-
tronic circuit will reduce and limit the output current.
The machine will continue to limit the output current
until the overload is removed.
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Section F-1
Section F-1
TABLE OF CONTENTS
-TROUBLESHOOTING & REPAIR SECTION-
Troubleshooting & Repair Section.......................................................................................Section F
How to Use Troubleshooting Guide............................................................................................F-2
PC Board Troubleshooting Procedures and Replacement.........................................................F-3
Troubleshooting Guide................................................................................................................F-4
Test Procedures ........................................................................................................................F-20
Input Power Factor Capacitor Voltage Check and Discharge Procedure..........................F-20
ARC Start Trigger Circuit Test.............................................................................................F-22
Power Board Test ...............................................................................................................F-25
Input Contactor Test ...........................................................................................................F-28
Pilot Transformer Test.........................................................................................................F-32
Feed-Thru PC Board Test...................................................................................................F-34
Protection PC Board Test...................................................................................................F-38
Main Transformer Test ........................................................................................................F-41
Control Transformer (T5) Voltage Test ................................................................................F-44
Control Board Test..............................................................................................................F-47
Static SCR Test...................................................................................................................F-51
Active SCR Test ..................................................................................................................F-54
Oscilloscope Waveforms ..........................................................................................................F-58
Normal Open Circuit Voltage Waveform (DC Stick Mode).................................................F-58
Normal Open Circuit Voltage Waveform (AC Stick Mode) .................................................F-59
Normal Open Circuit Voltage Waveform (DC TIG Mode) ...................................................F-60
Normal Open Circuit Voltage Waveform (AC TIG Mode)....................................................F-61
Typical Output Voltage Waveform – Machine Loaded (DC TIG Mode) ..............................F-62
AC TIG Mode (Balanced Waveform) ..................................................................................F-63
Abnormal Open Circuit Voltage – (DC TIG Mode, One
Output SCR Not Functioning).......................................................................................F-64
Abnormal Open Circuit Voltage – (AC TIG Mode, One
Output SCR Not Functioning).......................................................................................F-65
Replacement Procedures..........................................................................................................F-66
Control PC Board Removal and Replacement...................................................................F-66
Power PC Board Removal and Replacement ....................................................................F-68
Input Contactor (C1) Removal and Replacement ..............................................................F-70
Fan Motor and Blade Removal and Replacement .............................................................F-73
Output Rectifier Removal and Replacement......................................................................F-75
SCR Removal and Replacement ........................................................................................F-78
Rest after Repair .......................................................................................................................F-84
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F-2
F-2
TROUBLESHOOTING & REPAIR
HOW TO USE TROUBLESHOOTING GUIDE
WARNING
Service and repair should be performed by only Lincoln Electric Factory Trained Personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician and machine
operator and will invalidate your factory warranty. For your safety and to avoid Electrical Shock, please
observe all safety notes and precautions detailed throughout this manual.
This Troubleshooting Guide is provided to help
you locate and repair possible machine malfunc-
tions. Simply follow the three-step procedure
listed below.
Step 3. PERFORM COMPONENT TESTS. The
last column, labeled “Recommended Course of
Action,” lists the most likely components that
may have failed in your machine. It also specifies
the appropriate test procedure to verify that the
subject component is either good or bad. If there
are a number of possible components, check the
components in the order listed to eliminate one
possibility at a time until you locate the cause of
your problem.
Step 1. LOCATE PROBLEM (SYMPTOM). Look
under the column labeled “PROBLEM (SYMP-
TOMS). This column describes possible symp-
toms that the machine may exhibit. Find the list-
ing that best describes the symptom that the
machine is exhibiting. Symptoms are grouped
into three main categories: Output Problems,
Function Problems, and Welding Problems.
All of the referenced test procedures referred to in
the Troubleshooting Guide are described in detail
at the end of this chapter. Refer to the
Troubleshooting and Repair Table of Contents to
locate each specific Test Procedure. All of the
referred to test points, components, terminal
strips, etc., can be found on the referenced elec-
trical wiring diagrams and schematics. Refer to
the Electrical Diagrams Section Table of Contents
to locate the appropriate diagram.
Step 2. PERFORM EXTERNAL TESTS. The
second column, labeled “POSSIBLE AREAS OF
MISADJUSTMENT(S),” lists the obvious external
possibilities that may contribute to the machine
symptom. Perform these tests/checks in the
order listed. In general, these tests can be con-
ducted without removing the case wrap-around
cover.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs
safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before
you proceed. Call 216-383-2531 or 1-800-833-9353.
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F-3
F-3
TROUBLESHOOTING & REPAIR
PC BOARD TROUBLESHOOTING PROCEDURES AND REPLACEMENT
• Remove the PC Board from the static-shielding bag
and place it directly into the equpment. Don’t set
the PC Board on or near paper, plastic or cloth
which could have a static charge. If the PC Board
can’t be installed immediately, put it back in the sta-
tic-shielding bag.
WARNING
ELECTRIC SHOCK can kill.
Have an electrician install and ser-
vice this equipment.
machine OFF before working on
equipment. Do not touch electrically hot parts.
Turn the
• If the PC Board uses protective shorting jumpers,
don’t remove them until installation is complete.
• If you return a PC Board to The Lincoln Electric
Company for credit, it must be in the static-shield-
ing bag. This will prevent further damage and allow
proper failure analysis.
Sometimes machine failures appear to be due to PC
board failures. These problems can sometimes be
traced to poor electrical connections. To avoid prob-
lems when troubleshooting and replacing PC boards,
please use the following procedure:
4. Test the machine to determine if the failure symp-
tom has been corrected by the replacement PC
board.
NOTE: Allow the machine to heat up so that all elec-
trical components can reach their operating
temperature.
1. Determine to the best of your technical ability that
the PC board is the most likely component causing
the failure symptom.
5. Remove the replacement PC board and substitute
it with the original PC board to recreate the original
problem.
2. Check for loose connections at the PC board to
assure that the PC board is properly connected.
a. If the original problem does not reappear
by substituting the original board, then the
PC board was not the problem. Continue
to look for bad connections in the control
wiring harness, junction blocks, and termi-
nal strips.
3. If the problem persists, replace the suspect PC
board using standard practices to avoid static elec-
trical damage and electrical shock. Read the warn-
ing inside the static resistant bag and perform the
following procedures.
PC Board can be damaged by
static electricity.
b. If the original problem is recreated by the
substitution of the original board, then the
PC board was the problem. Reinstall the
replacement PC board and test the
machine.
• Remove your body’s static
charge before opening the stat-
ic-shielding bag. Wear an anti-
ATTENTION
Static-Sensitive
Devices
Handle only at
static wrist strap. For safety,
use a 1 Meg ohm resistive cord
connected to a grounded part of
the equipment frame.
6. Always indicate that this procedure was followed
when warranty reports are to be submitted.
Static-Safe
NOTE: Following this procedure and writing on the
Workstations
warranty
report,
“INSTALLED
AND
• If you don’t have a wrist strap,
SWITCHED PC BOARDS TO VERIFY PROB-
LEM,” will help avoid denial of legitimate PC
board warranty claims.
touch an unpainted, grounded
part of the equipment frame.
Keep touching the frame to pre-
vent static build-up. Be sure not
to touch any electrically live
parts at the same time.
Resuable
Container
Do Not Destroy
• Tools which come in contact with the PC Board
must be either conductive, anti-static or static-dis-
sipative.
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F-4
F-4
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
OUTPUT PROBLEMS
Major physical or electrical dam-
age is evident when the sheet
metal cover(s) are removed.
1. Contact your local authorized
Lincoln Electric Field Service
Facility for technical assis-
tance.
1. Contact the Lincoln Electric
Service Department, 216-383-
2531 or 1-800-833-9353
(WELD).
Machine is dead – no output – no
fans – no displays.
1. Check the input voltage at the
machine. Input voltage must
match the rating plate and the
reconnect panel.
1. If when the “start” button is
pushed the pilot light is lit and
the input contactor (CR1) acti-
vates, check the wiring at the
reconnect panel and also to
the main transformer primary
coils.
2. Check for blown or missing
fuses in the input lines.
3. Check for a blown or missing
control circuit fuse F1.
2. Perform the Input Contactor
Test.
4. The machine secondary
thermostat may be open.
Allow machine to cool.
3. Perform the Main Transformer
Test.
4. If when the “start” button is
pushed the pilot light does
NOT light and the input con-
tactor does NOT activate,
check the start/stop button for
proper operation.
5. Perform the Pilot Transformer
Test.
6. If when the “start” button is
pushed the pilot light is lit and
the input contactor does NOT
activate, perform the Input
Contactor Test.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-5
F-5
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
OUTPUT PROBLEMS
The input contactor activates
when “start” button is pushed but
will NOT stay closed. Machine
shuts off when “start” button is
released.
1. Check the input voltage at the
machine. Input voltage must
match the rating plate and the
reconnect panel.
1. Perform the Input Contactor
Test.
2. Perform the Control
Transformer Test.
2. Blown or missing control cir-
cuit fuse (F1).
3. Perform the Feed – Thru PC
Board Test.
4. Perform the Control Board
Interlock Test.
5. The power board may be
faulty. Replace.
The machine shuts off and the
control fuse (F1) repeatedly fails.
1. Check the input voltage at the
machine. Input voltage must
match the rating plate and the
reconnect panel.
1. Perform the Control
Transformer Test.
2. Perform the Power Board
Test.
2. Make sure the fuse is the cor-
rect rating (1/2 amp).
3. The control board may be
faulty. Replace.
3. The input voltage may be too
high (more than 10% over
rated).
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-6
F-6
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
OUTPUT PROBLEMS
Fans and display are functional.
No output from machine in either
Stick or TIG modes.
1. The primary thermostat may be 1. If the machine works properly
open. Allow machine to cool.
in Local control mode but not
in Remote control, then per-
form the Protection Board
Test.
2. If the machine is in Remote
control mode, make sure a
Lincoln remote control device
is connected to the amphenol.
2. If the machine does NOT have
output in either mode, Local or
Remote, check the primary
thermostat for proper opera-
tion. It is normally closed.
3. If the machine works properly
in the Local control mode,
check or replace the remote
control device.
3. Perform the Arc Start Trigger
Circuit Test.
4. Perform the SCR Bridge Test.
5. Perform the Control
Transformer Test.
6. Perform the Power Board
Test.
7. The control board may be
faulty. Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-7
F-7
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
OUTPUT PROBLEMS
The machine shuts off (pilot light
goes out and the fans stop) when
the Arc Start Switch or Amptrol is
activated.
1. The input voltage may be too
high (more than 10% over
rated).
1. Perform the SCR Bridge Test.
2. Perform the Power Board
Test.
2. The Arc Start switch may be
faulty. Check or replace.
3. Perform the Control Board
Test.
4. Shunt may be faulty or over-
heated. Check for loose con-
nections and replace shunt if
necessary.
The 115VAC receptacle does not
work. The machine operates nor-
mally.
1. The circuit breaker CB1 may
have opened. Reset if neces-
sary.
1. The circuit breaker may be
faulty. Test or replace.
2. If the fans are running, check
the receptacle and the associ-
ated wiring.
2. Check for the presence of
115VAC at the receptacle.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-8
F-8
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
FUNCTION PROBLEMS
Digital display does not light.
Machine turns on and operates
normally.
1. Contact your local authorized
Lincoln Electric Field Service
Facility.
1. Check for 5VDC from 2J7+ to
4J7- on the display board. If
the voltage is present and the
display does NOT light, the
display board may be faulty.
Replace.
2. The control board may be
faulty. Replace.
The display lights but a current
cannot be preset.
1. Contact your local authorized
Lincoln Electric Field Service
Facilty.
1. Set the Peak Current control
(R10) to the 12 o’clock posi-
tion. Position the Start Current
switch (S13) to the off position.
The machine should weld at
approximately 80 amps. If the
machine welds properly but
does NOT display the actual
welding current, the meter
board may be defective.
Replace.
1a. The control board may be
defective. Replace.
2. If the machine does NOT weld
properly, check or replace the
Peak Current control poten-
tiometer (R10).
2a. The control board may be
faulty. Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-9
F-9
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
FUNCTION PROBLEMS
1. In Stick mode the machine
welds at a very low output,
regardless of the peak current
control setting.
1. If the machine is in the Remote 1. If the machine works properly
control mode, make sure a
Lincoln remote control device
is connected to the amphenol.
in Local control mode but not
in Remote mode, perform the
Protection Board Test.
2. The Start Current may be set
too low for the electrode size
being used.
2. If the machine operates prop-
erly in TIG mode but not in
Stick mode, the control board
may be faulty. Replace.
3. If the machine works properly
in Local control mode, check
or replace the remote control
device.
3. If the output is low in all
modes, perform the SCR
Bridge Test.
4. If the machine works properly
in TIG mode, contact your
local authorized Lincoln
4. The power board may be
faulty. Replace.
5. The control board may be
faulty. Replace.
Electric Field Service Facility.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-10
F-10
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
FUNCTION PROBLEMS
The machine welds at very high
outputs, regardless of the Peak
Current control setting.
1. Make sure the start controls
are set correctly for the
process being used.
1. Perform the SCR Bridge Test.
2. The power board may be
faulty. Replace.
2. If the machine is in Remote
control mode, change modes
to Local control. If the prob-
lem is resolved, the remote
control unit may be defective.
3. The control board may be
faulty. Replace.
The Arc Force control has no
effect on the arc.
1. The Arc Force control is active
only in the Stick mode.
1. Check the Arc Force control
potentiometer for correct resis-
tance and proper operation.
2. The effect of the Arc Force
control will be less noticeable
at high welding currents. Weld
at low currents (less than 150
amps) and check the Arc Force
control function.
2. Check the continuity of leads
#441 and #445. See Wiring
Diagram.
3. The control board may be
faulty. Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-11
F-11
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
TIG MODE PROBLEMS
Gas and/or water do not flow,
even though the gas and/or water
LEDs are lit.
1. The machine must be in TIG
mode. The gas, water and
high frequency circuits do NOT
function in Stick mode.
1. Check for proper operation of
the gas and/or water sole-
noids.
2. If 115VAC is applied to the
solenoids, they should activate
and allow gas or water to flow.
2. Check the gas and/or water
supplies for adequate pressure
or kinked or broken hoses.
3. If 115VAC is applied to the
solenoids and they do NOT
activate, the solenoids may be
faulty. Replace.
4. Perform the Control Board
Test.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-12
F-12
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
TIG MODE PROBLEMS
No high frequency. Machine is in
TIG Mode and has normal output.
1. In order for the high frequency
to operate, the machine must
be either in Start Only mode or
Continuous High Frequency
mode.
1. Check the high voltage trans-
former (T3). The normal resis-
tance of the secondary wind-
ing is 12.5 k-ohms.
115VAC is applied to the pri-
mary of T3. A very high volt-
age is developed on the sec-
ondary winding. For assis-
tance call the Lincoln Electric
Service Dept., (216) 383-2531
or 1-800-833-9353 (WELD).
2. The high frequency spark gap
may be too large or shorted.
Check the gap per mainte-
nance instructions.
2. Check the values of R6 and
C6. Replace if necessary.
3. Check the continuity of coils
L4 and L5. Normal resistance
is approximately 10 ohms.
4. Perform the Feed – Thru
Board Test.
5. Perform the Control Board
High Frequency Signal Test.
6. The power board may be
faulty. Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-13
F-13
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
TIG MODE PROBLEMS
Weak high frequency – machine
has normal welding output.
1. The spark gap may be misad-
justed. Check and reset per
maintenance instructions.
1. Make sure that 115VAC is
being applied to the primary of
the high voltage transformer
(T3). See Wiring Diagram.
2. Improper shielding gas flow.
Adjust for a flow of 10 to 30
CFH (4.7 to 14.1 l/min.) for
most applications.
2. Check for an open or arcing
high frequency component.
Replace as required.
(Examples: R6, C6, C3, R4)
3. Work and electrode cables
may be in poor condition,
3. If spark is weak at the spark
gap, check or replace the high
frequency circuit. (Examples:
T3, L4, L5).
allowing the high frequency to
“leak off.” Use good quality
cables with a high natural rub-
ber content, such as Lincoln
Stable Arc Cable. Cables
should be as short as possible.
Lack of penetration in AC TIG
welding.
1. The AC Wave Balance control
may be set improperly – set-
tings above 3 give increased
penetration.
1. Check the AC Wave Balance
control potentiometer (R12) for
correct resistance and proper
operation. See Wiring
Diagram.
2. Check leads #443 and #444
for continuity from the AC
Wave Balance control poten-
tiometer to the lower control
panel. See Wiring Diagram.
3. Perform the SCR Rectifier
Bridge Tests.
4. The control board may be
faulty. Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-14
F-14
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
TIG MODE PROBLEMS
Black areas along weld bead.
1. The tungsten electrode may be 1. This may be a welding proce-
contaminated. Replace or
sharpen.
dure problem.
Contact The Lincoln Electric
Service Department, (216) 383-
2531 or 1-800-833-9353 (WELD).
2. Shielding gas flow may be
insufficient.
3. Contaminated gas or faulty gas
line or torch.
Black areas along weld bead at or 1. Increase the gas post flow
near end of weld. time.
1. This may be a welding proce-
dure problem.
Contact The Lincoln Electric
Service Department, (216) 383-
2531 or 1-800-833-9353 (WELD).
The machine has low output when 1. The machine must be in Local
1. Contact The Lincoln Electric
Service Department, (216) 383-
2531 or 1-800-833-9353
(WELD).
in TIG 4-Step mode.
control mode when 4-Step is
used.
2. The machine output control
may be set iincorrectly.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-15
F-15
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
TIG MODE PROBLEMS
Open circuit voltage is present at
the output terminals even when
the Arc Start switch or Amptrol is
NOT actuated.
1. The Arc Start switch or
1. Check the trigger circuit.
Perform the Arc Start Trigger
Circuit Test.
Amptrol may be defective.
There should not be any conti-
nuity between pins “D” and “E”
on the Arc Start cable connec-
tor, unless the unit is actuated.
2. The control board may be
faulty. Replace.
3. The power board may be
faulty. Replace.
Arc rectification when AC TIG
welding.
1. The tungsten electrode may be 1. Check components R6 and C6
too small for the process.
in the high voltage transformer
primary circuit. Replace if nec-
essary.
2. The AC Wave Balance control
may be misadjusted. Adjust
for more penetration.
2. Perform the SCR Rectifier
Bridge Tests.
3. If helium shielding gas is being
used, reduce the percentage of 3. The control board may be
helium. faulty. Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-16
F-16
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
TIG MODE PROBLEMS
The machine output is intermit-
tently lost. Gas flow and high fre-
quency are also interrupted.
1. The problem may be caused
by high frequency inteference.
Make sure that the machine is
grounded properly according
to the installation instructions.
If there are other high frequen-
cy sources in the area, make
certain they are grounded
properly.
1. The machine internal ground
connections may be loose.
Check the mounting screws on
the protection board, the
bypass boards, and the feed-
thru board.
2. The protection or bypass
boards may be faulty. Check
or replace.
2. Check the Arc Start switch or
Amptrol for proper operation
and loose connections.
3. Perform the Arc Start Trigger
Circuit Test.
The arc “flutters” when TIG weld-
ing.
1. The tungsten electrode may be 1. Check for loose shunt connec-
too large in diameter.
tions, leads #222 and #221.
See Wiring Diagram.
2. The tungsten electrode may
needed sharpening.
2. Check polarity switch for loose
or faulty connections.
3. If helium shielding gas is used,
reduce the percentaghe of heli- 3. Perform the SCR Rectifier
um.
Bridge Tests.
4. Adjust the gas flow rate to the
proper level for the process
being used.
4. Check components R6 and C6
in the high voltage transformer
primary circuit. Replace if nec-
essary.
5. Check gas hoses and connec-
tions for leaks.
5. The control board may be
faulty. Replace.
6. The power board may be
faulty. Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-17
F-17
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
FUNCTION PROBLEMS
The Pulsar does not seem to
operate.
1. If the Start controls are used,
pulsing does not begin until
the end of the “start” time,
which can be as much as 10
seconds.
1. Check the Pulse controls (R18,
R19 and R20) for correct resis-
tance and proper operation.
See Wiring Diagram.
2. The control board may be
faulty. Replace.
2. Check the Pulses Per Second
control. If it is set near mini-
mum, each pulse may be as
long as ten seconds. Set all
three of the pulse controls near
the midpoints to see the
pulser’s effects.
3. The Pulse % On control may
be set at either extreme. If
that is the case, the pulses
may be too short to be seen.
The Spot Timer does not last as
long as the nameplate setting.
1. When in the 2-Step trigger
mode, be sure to keep the Arc
Start switch or Amptrol
1. Check the Spot Timer control
potentiometer (R16) for correct
resistance and proper opera-
tion.
pressed until the spot time is
completed. Releasing the Arc
Start switch before the Spot
Timer has timed out will cause
the arc to go out.
2. The control board may be
faulty. Replace.
The Spot Timer lasts much longer
than the nameplate setting.
1. Make sure the Crater Fill
switch is turned off. If it is on,
the actual weld time will be the
spot time plus the crater fill
time.
1. Check the Spot Timer control
potentiometer (R16) for correct
resistance and proper opera-
tion.
2. The control board may be
faulty. Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-18
F-18
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
FUNCTION PROBLEMS
When using Crater Fill the arc
goes out before the final crater fill
current level is reached.
1. The Crater Fill % Peak Current
control may be set too low for
the tungsten being used.
1. Check the Crater Fill Fade Out
control potentiometer for cor-
rect resistance and proper
operation.
Increase the Crater Fill % Peak
Current control until the final
crater fill current is within the
tungsten’s operating range.
2. The control board may be
faulty. Replace.
2. If using the Pulser in conjunc-
tion with the Crater Fill, the
Background % Peak Current
may be too low for the tung-
sten as the current is
downsloping in crater fill. The
best solution is to increase the
Background % Peak Current
level.
3. If welding with AC, use
“Continuous” high frequency.
The high frequency will stabi-
lize the arc as the current goes
down.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-19
F-19
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
STICK WELDING PROBLEMS
Stick electrode “blasts off” when
touched to workpiece. The
machine operates properly in the
TIG mode.
1. The weld current is set too
high for electrode size.
1. The control board may be
faulty. Replace.
2. If the Start switch is ON, the
start current may be set too
high for electrode size.
3. The Arc Force control may be
set too high.
The arc seems too hot, and
1. The Arc Force control may be
set too high.
1. The control board may be
faulty. Replace.
reducing the Peak Current control
does not help. The machine oper-
ates properly in the TIG mode.
2. If the Start switch is ON, the
start current may be set too
high or the start time may be
set too long.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
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F-20
F-20
TROUBLESHOOTING & REPAIR
INPUT POWER FACTOR CAPACITOR VOLTAGE CHECK
AND DISCHARGE PROCEDURE
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
PURPOSE FOR THE PROCEDURE
This procedure ensures that the power factor capacitors are discharged, for greater safety
when you are working on the Square Wave TIG 355 with INPUT POWER REMOVED.
MATERIALS NEEDED
Volt/Ohmmeter capable of testing 600 VAC
5/16" Nut driver
Resistor (500 ohms, 25 watts minimum)
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F-21
F-21
TROUBLESHOOTING & REPAIR
INPUT POWER FACTOR CAPACITOR VOLTAGE CHECK
AND DISCHARGE PROCEDURE (continued)
FIGURE F.1 – POWER FACTOR CAPACITOR DISCHARGE DETAILS
TEST PROCEDURE
1. Remove input power to the machine.
a. Grip the 500 ohm resistor with insu-
lated gloves and insulated gripping pli-
ers.
2. With the 5/16" nut driver, remove the sheet
metal screws that hold the right case side
in place. Remove the right case side.
b. Hold the resistor across the terminals
on each capacitor for 20 seconds. See
Figure F.1.
3. With the volt/ohmmeter, carefully check the
voltage across the input power factor
capacitors. When input power is removed,
the voltage across each capacitor should
be zero. (Normally, the capacitors dis-
charge through the primary winding in the
main transformer.)
c. With the volt/ohmmeter, recheck each
capacitor for voltage.
6. After all the capacitors are discharged
completely, check for broken capacitor
leads or an open primary winding on the
main transformer, which would have pre-
vented the capacitors from discharging
normally.
4. If capacitor voltage is zero, you may begin
working on the Square Wave TIG 355.
5. If any voltage is present, DISCHARGE
EACH INDIVIDUAL CAPACITOR as follows:
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F-22
F-22
TROUBLESHOOTING & REPAIR
ARC START TRIGGER CIRCUIT TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
This test will determine if the wiring and connections are good between the 6-pin amphenol
receptacle and the protection board, and also between the protection board and the feed-
thru board. It will also determine if 24 VAC is being supplied to the trigger circuit.
MATERIALS NEEDED
Volt/Ohmmeter (Multimeter)
5/16" Nut driver
Arc Start Trigger Circuit, Figure F.3
Square Wave TIG Wiring Diagram (located in the Electrical Diagrams section of this
manual)
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F-23
F-23
TROUBLESHOOTING & REPAIR
ARC START TRIGGER CIRCUIT TEST (continued)
FIGURE F.2 – 6-PIN AMPHENOL RECEPTACLE
F
E
A
D
B
C
6. With the volt/ohmmeter, check for 24 VAC
at pins 1J9 to 3J9.
TEST PROCEDURE
1. Remove input power to the machine.
• If 24 VAC is present, the control PC board
may be faulty. NOTE: 24 VAC should be
present at pins 1J9 to 3J9 only when the Arc
Start switch is closed.
2. With the 5/16" nut driver, remove the
screws and carefully lower the front control
panel.
3. Locate plug J9 on the control PC board.
• If 24 VAC is missing or low, check for 24
VAC at the T5 transformer. See the Wiring
Diagram. If 24 VAC is missing or low at the
transformer leads, perform the Control
Transformer Test.
WARNING
ELECTRIC SHOCK can kill.
• If 24 VAC is present at the transformer leads,
remove input power to the machine and
check the continuity and resistance of the
leads and coils on and between the feed-
thru board and the protection board. See
Figure F.3.
• With input power ON,
there are high voltages
inside the machine. Do
not reach into the machine
or touch any internal part
of the machine while
power is on.
7. Also check the continuity of the leads from
the protection board to the 14-pin amphe-
nol receptacle. It should be zero ohms.
See the Wiring Diagram.
4. Turn on input power to the machine.
5. Close the Arc Start switch or jumper pins
"D" to "E" at the 6-pin amphenol recepta-
cle. See Figure F.2.
8. After the tests are complete, install the front
control panel, using the 5/16" nut driver.
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F-24
F-24
TROUBLESHOOTING & REPAIR
ARC START TRIGGER CIRCUIT TEST (continued)
FIGURE F.3 – ARC START TRIGGER CIRCUIT
FEED - THRU
PROTECTION
BOARD
BOARD
T5
CONTROL
REMOTE
L11
L3
TRANSFORMER
#204
1J16
1J18
8J23
3J22
RECEPTACLE
4.2 ohms
max.
4.2 ohms
max.
D
CONTROL
BOARD
24VAC
ARC
START
SWITCH
E
1J9
3J9
L13
L6
3J16
5J18
#207
5J23
6J22
4.2 ohms
max.
4.2 ohms
max.
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F-25
F-25
TROUBLESHOOTING & REPAIR
POWER BOARD TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
This test will determine if the correct input voltages are being supplied to the power board
and also if the proper voltages are being generated by the power board.
MATERIALS NEEDED
Volt/Ohmmeter (Multimeter)
5/16" Nut driver
Power Board Voltage Test Chart
Square Wave TIG Wiring Diagram (located in the Electrical Diagrams section of this
manual)
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F-26
F-26
TROUBLESHOOTING & REPAIR
POWER BOARD TEST (continued)
FIGURE F.4 - POWER BOARD TEST POINTS
G2081-[
]
10
9
8
7
2
6
1
12 11 10 9
8
7
J2
J4
5
4
3
6
5
4
3
2
1
SQUARE WAVE POWER
• Apply power and press the start button.
TEST PROCEDURE
• If the correct voltages are being applied
to the power board but NOT generated
by the power board, the power board
may be faulty.
1. Remove input power to the machine.
2. With the 5/16" nut driver, remove the
screws and carefully lower the front control
panel.
• If the background voltages are NOT
being applied to the power board, the
control transformer, the background
rectifier, or the associated wiring may be
faulty.
3. On the power board, locate the test points
that are called out in the following Power
Board Voltage Test Chart. See Figure F.4.
4. Connect the volt/ohmmeter to each set of
test points and compare your reading to the
expected reading from the chart.
5. After the tests are completed and the prob-
lem repaired, install the front control panel,
using the 5/16" nut driver.
WARNING
ELECTRIC SHOCK can kill.
• With input power ON,
there are high voltages
inside the machine. Do
not reach into the machine
or touch any internal part
of the machine while
power is on.
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F-27
F-27
TROUBLESHOOTING & REPAIR
POWER BOARD VOLTAGE TEST CHART
Check Points
Signals Being
Checked
Expected
Reading
Special Conditions
for Test
IJ4 to 2J4
4J4 to 6J4
4J4 to 5J4
10J4 to 12J4
AC supply voltage
from T5 transformer
10VAC
32VAC
16VAC
36VAC
None
None
None
None
AC supply voltage
from T5 transformer
AC supply voltage
from T5 transformer
AC supply voltage
from T5 transformer
3J2(+) to 5J2
4J2(-) to 5J2
IJ2(+) to 2J2
Regulated +15VDC
Regulated -15VDC
Unregulated DC
+15VDC
-15VDC
+14VDC
LED 1 ON
LED 2 ON
None
Note: LED 3 should be ON when gate signal is applied to SCR 1.
LED 4 should be ONE when gate signal is applied to SCR 4.
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F-28
F-28
TROUBLESHOOTING & REPAIR
INPUT CONTACTOR TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid electri-
cal shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting
assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
This test will determine if the input contactor is receiving the correct coil voltage and if the con-
tacts are functioning correctly.
MATERIALS NEEDED
Volt/Ohmmeter (Multimeter)
5/16" Nut driver
External 120 VAC supply
Input Contactor (CR1) Simplified Control Circuit, Figure F.6
Square Wave TIG Wiring Diagram (located in the Electrical Diagrams section of this manual)
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F-29
F-29
TROUBLESHOOTING & REPAIR
INPUT CONTACTOR TEST (continued)
FIGURE F.5 - INPUT CONTACTOR TEST POINTS
243
244
TEST PROCEDURE
WARNING
1. Remove input power to the machine.
ELECTRICAL ARCING can injure.
2. With the 5/16" nut driver, remove the
machine top and sides.
• Never mechanically close the contactor with
input power (line voltage) applied and the
machine contactor cover removed.
3. Locate the two leads, #243 and #244, con-
nected to the input contactor coil. See
Figure F5.
4. Connect the volt/ohmmeter to the leads.
5. Turn on input power to the machine and
press the Start button.
WARNING
6. Check for 120 VAC at the contactor coil
leads.
ELECTRIC SHOCK can
kill.
• If 120 VAC is NOT present when the Start
button is pressed, check the normally
closed (NC) secondary thermostat, the
power Start/Stop pushbutton and associat-
ed circuitry. See Figure F.6, Input Contactor
(CR1) Simplified Control Circuit. Also per-
form the Pilot Transformer Test.
• With input power ON,
there are high voltages
inside the machine. Do
not reach into the
machine or touch any
internal part of the
machine while power is
on.
• If 120 VAC is present and the contactor does
not activate, the input contactor is faulty.
Replace.
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F-30
F-30
TROUBLESHOOTING & REPAIR
INPUT CONTACTOR TEST (continued)
• If 120 VAC is present when the Start button
is held in but the contactor does not stay
activated when the button is released, check
the CR1 interlock, the power Start/Stop
pushbutton, and associated circuitry. See
Figure F.6, Input Contactor (CR1) Simplified
Control Circuit. Also perform the Control
Board Test.
Test for Contact Continuity
1. Remove ALL input power to the machine.
2. Perform the power factor capacitor dis-
charge procedure.
3. Locate the two leads, #243 and #244, con-
nected to the input contactor coil. See
Figure F6.
4. Use the external 120 VAC supply to apply
power to the input contactor coil.
• If the contactor does NOT activate, it is
faulty. Replace.
• If the contactor does activate, check the
continuity across the contacts. A normal
reading should be zero ohms or very low
ohms.
• If the resistance is high, the contactor is
faulty. Replace.
5. With the contactor NOT activated, check
the continuity across the contacts. See
Figure F.6.
• If the resistance is infinite or very high
across the contacts, the contactor is good.
• If the resistance is low, the contactor is
faulty. Replace.
6. After the tests are completed and the prob-
lem repaired, install the machine sides and
top, using the 5/16" nut driver.
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F-31
F-31
TROUBLESHOOTING & REPAIR
INPUT CONTACTOR TEST (continued)
FIGURE F.6 - INPUT CONTACTOR (CR1) SIMPLIFIED CONTROL CIRCUIT
T5 CONTROL
TRANSFORMER
R
W
R
1
0
J
1
2
J
4
5
J
4
4
STOP
.33 OHMS
MAX.
9J15
4J3
3J17
#241
#272
L9
X1
X2
START
CR 1
T2 PILOT
TRANSFORMER
.33 OHMS
MAX.
OVERVOLTAGE
FEEDBACK
INTERLOCK
10J3
10J2
8J15
2J17
2J3
#242
#273
L8
#243
CR 1
FEED - THRU
BOARD
POWER
BOARD
CONTROL
BOARD
#244
N. C.
SECONDARY
THERMOSTAT
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F-32
F-32
TROUBLESHOOTING & REPAIR
PILOT TRANSFORMER TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
This test will determine if the correct voltage is being applied to the primary of the pilot
transformer and induced on the secondary.
MATERIALS NEEDED
Volt/Ohmmeter (Multimeter)
5/16" Nut driver
Square Wave TIG Wiring Diagram (located in the Electrical Diagrams section of this
manual)
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F-33
F-33
TROUBLESHOOTING & REPAIR
PILOT TRANSFORMER TEST (continued)
FIGURE F.7 - PILOT TRANSFORMER CONNECTIONS
X1
X2
TEST PROCEDURE
1. Remove input power to the machine.
6. Check for 120 VAC at the X1 and X2 termi-
nals.
2. With the 5/16" nut driver, remove the
machine top and sides.
• If 120 VAC is present at X1 and X2, the pilot
transformer is good.
3. Locate terminals X1 and X2 connected to
the pilot transformer secondary. See Figure
F.7.
• If 120 VAC is NOT present at X1 and X2,
check for the correct primary voltage at
leads H1 to HX, depending on the input volt-
age being applied to the machine. See the
machine Wiring Diagram.
4. Connect the volt/ohmmeter to X1 and X2.
WARNING
NOTE: H1 is located at L1 on the input side of
CR1 input contactor.
ELECTRIC SHOCK can kill.
If the correct voltage is being applied to the
primary of the pilot transformer and 120 VAC is
not present at terminals X1 and X2 of the sec-
ondary winding, the pilot transformer may be
faulty. Replace.
• With input power ON,
there are high voltages
inside the machine. Do
not
reach into the
machine or touch any
internal part of the
machine while power is
on.
NOTE: The secondary voltage will vary with
fluctuations in the input line voltage.
7. After the tests are completed and the prob-
lem repaired, install the machine sides and
top, using the 5/16" nut driver.
5. Turn on input power to the machine.
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F-34
F-34
TROUBLESHOOTING & REPAIR
FEED-THRU PC BOARD TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
This test will determine if the feed-thru PC board circuitry is intact and capable of passing
signal currents.
MATERIALS NEEDED
Volt/Ohmmeter (Multimeter)
5/16" Nut driver
Phillips head screw driver
Square Wave TIG Wiring Diagram (located in the Electrical Diagrams section of this
manual)
Feed-Thru PC Board Schematic
Feed-Thru PC Board Resistance Test Points Chart
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F-35
F-35
TROUBLESHOOTING & REPAIR
FEED-THRU PC BOARD TEST (continued
FIGURE F.8 - FEED-THRU PC BOARD LOCATION
TEST PROCEDURE
1. Remove input power to the machine.
• If any of the resistances are out of specifica-
tion, replace the feed-thru PC board.
2. With the 5/16" nut driver, remove the
machine top and sides.
8. After the tests are completed and the prob-
lem repaired, install and connect the feed-
thru PC board:
3. Perform the power factor capacitor dis-
charge procedure.
• Carefully mount the board to the floor of the
control box using the 4 phillips head screws.
4. Remove plugs J15, J16, J17, and J18 from
the feed-thru PC board. See Figure F.8 for
location.
• Connect plugs J15, J16, J17, and J18 to the
board.
5. Remove the 4 phillips head screws mount-
ing the feed-thru PC board to the floor of
the control box. See Figure F.8.
9. With the 5/16" nut driver, install the
machine sides and top.
6. Carefully remove the feed-thru PC board.
7. Test for the resistances between the check
points listed on the Feed-Thru PC Board
Resistance Test Points Chart. See Figures
F.9 and F.10.
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F-36
F-36
TROUBLESHOOTING & REPAIR
FEED-THRU PC BOARD TEST (continued)
FIGURE F.9 - FEED-THRU PC BOARD PLUG DETAILS –
PLUGS J15 AND J16
J18
J17
FIGURE F.10 - FEED-THRU PC BOARD PLUG DETAILS –
PLUGS J17 AND J18
8
7
6
5
10 9
8
3
7
2
6
1
J18
J17
4
3
2
1
5
4
VIEW FROM EDGE OF BOARD
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F-37
F-37
TROUBLESHOOTING & REPAIR
FEED-THRU PC BOARD TEST (continued)
FEED THRU PC BOARD RESISTANCE TEST POINTS
Check Points
Component(s) Being
Checked
Maximum Allowable
Resistance
5J15 to 7J17
4J15 to 6J17
6J15 to 10J17
7J15 to 9J17
10J15 to 4J17
2J15 to 1J17
8J15 to 2J17
9J15 to 3J17
1J15 to 5J17
1J16 to 1J18
2J16 to 8J17
3J16 to 5J18
5J16 to 4J18
6J16 to 8J18
7J16 to 7J18
8J16 to 6J18
L1 and Board Trace
L2 and Board Trace
L4 and Board Trace
L5 and Board Trace
L6 and Board Trace
L7 and Board Trace
L8 and Board Trace
L9 and Board Trace
L10 and Board Trace
L11 and Board Trace
L12 and Board Trace
L13 and Board Trace
L15 and Board Trace
L16 and Board Trace
L17 and Board Trace
L18 and Board Trace
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
.60 OHMS (.50 Typical)
.60 OHMS (.50 Typical)
.60 OHMS (.50 Typical)
.60 OHMS (.50 Typical)
.60 OHMS (.50 Typical)
.60 OHMS (.50 Typical)
.60 OHMS (.50 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
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F-38
F-38
TROUBLESHOOTING & REPAIR
PROTECTION PC BOARD TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
This test will determine if the protection PC board circuitry is intact and capable of passing
signal currents.
MATERIALS NEEDED
Volt/Ohmmeter (Multimeter)
5/16" Nut driver
Phillips head screw driver
Square Wave TIG Wiring Diagram (located in the Electrical Diagrams section of this
manual)
Protection PC Board Schematic
Protection PC Board Resistance Test Points Chart
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F-39
F-39
TROUBLESHOOTING & REPAIR
PROTECTION PC BOARD TEST (continued)
FIGURE F.11- PROTECTION PC BOARD LOCATION AND MOUNTING DETAILS
TEST PROCEDURE
1. Remove input power to the machine.
7. After the tests are complete and the prob-
lem repaired, install and connect the pro-
tection PC board.
2. With the 5/16" nut driver, remove the
screws and carefully lower the front control
panel.
• Carefully mount the protection PC board to
the front panel. Take note of the washer
placement; the washers must be replaced
correctly to be sure that the protection PC
board is grounded properly. See Figure
F.11.
3. Remove plugs J22 and J23 from the pro-
tection PC board. See Figure F.11 for loca-
tion.
4. With the phillips head screw driver, remove
the three screws mounting the protection
PC board to the front panel. Note washer
placement.
• Connect plugs J22 and J23.
8. Install the front control panel, using the
5/16" nut driver.
5. Carefully remove the protection PC board.
6. Test for the resistances between the check
points listed on the Protection PC Board
Resistance Test Points Chart.
• If any of the resistances are out of specifica-
tion, replace the protection PC board.
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F-40
F-40
TROUBLESHOOTING & REPAIR
PROTECTION PC BOARD TEST (continued)
PROTECTION PC BOARD RESISTANCE TEST POINTS CHART
Test Points
Component(s) Being
Tested
Maximum Allowable
Resistance
1J22 to 3J23
2J22 to 4J23
3J22 to 7J23
5J22 to 1J23
4J22 to 2J23
6J22 t 5J23
3J22 to 8J23
7J23 to 8J23
L1 and Board Trace
L2 and Board Trace
L3 and Board Trace
L4 and Board Trace
L5 and Board Trace
L6 and Board Trace
L3 and Board Trace
Board Trace
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
4.2 OHMS (3.9 Typical)
Zero (0) Ohms
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F-41
F-41
TROUBLESHOOTING & REPAIR
MAIN TRANSFORMER TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
This test will determine if the correct voltage is being applied to the primary of the main
transformer and induced on the secondary and auxiliary windings.
MATERIALS NEEDED
Volt/Ohmmeter (Multimeter)
5/16" Nut driver
Square Wave TIG Wiring Diagram (located in the Electrical Diagrams section of this
manual)
Main Transformer Voltage and Test Points Chart
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F-42
F-42
TROUBLESHOOTING & REPAIR
MAIN TRANSFORMER TEST (continued)
FIGURE F.12 - MAIN TRANSFORMER LOCATION AND WIRING DETAILS
X5
X6
X1
X2
X7
X3
X4
TEST PROCEDURE
WARNING
1. Remove input power to the machine.
ELECTRIC SHOCK can kill.
2. With the 5/16" nut driver, remove the
machine top and sides.
• With input power ON, there are high volt-
ages inside the machine.
Do not reach into the
machine or touch any inter-
nal part of the machine while
power is on.
3. Perform the power factor capacitor dis-
charge procedure.
4. Inspect the input contactor, reconnect
panel, and primary leads to the main trans-
former for loose or faulty connections.
5. Check the reconnect panel to make sure
that the single phase AC power supplied to
the machine is properly connected.
7. Turn on input power to the machine.
6. Locate leads X1 though X7. See Figure
F.12.
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F-43
F-43
TROUBLESHOOTING & REPAIR
MAIN TRANSFORMER TEST (continued)
7. Check the voltages at the test points listed
on the Main Transformer Voltage Test
Points Chart.
• If all the secondary or auxiliary voltages are
low or missing and the correct input voltage
is applied to the main transformer, then the
primary winding is faulty.
NOTE: Readings will fluctuate if line voltages
fluctuate.
8. After the tests are completed and the prob-
lem repaired, install the machine sides and
top, using the 5/16" nut driver.
• If any of the secondary or auxiliary voltages
is missing or out of specification and the
correct input voltage is applied to the prima-
ry winding, the main transformer may be
faulty.
MAIN TRANSFORMER VOLTAGE TEST POINTS CHART
Secondary and Auxiliary
Leads
Test Point Location
Approximate Voltages
X1 to X2
X3 to X4
X5 to X6
X2 to X7
Aluminum secondary leads
120VAC receptacle
84 to 89VAC
117 to 125VAC
22 to 24VAC
77 to 81VAC
Background rectifier
Aluminum secondary leads
NOTE: Readings will fluctuate if line voltages are unusually high or low.
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F-44
F-44
TROUBLESHOOTING & REPAIR
CONTROL TRANSFORMER (T5) VOLTAGE TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
The following procedure will determine if the correct voltage is being applied to the primary
of the control transformer and induced on the secondary.
MATERIALS NEEDED
Volt/Ohmmeter (Multimeter)
5/16” Nut Driver
Machine Wiring Diagrams (See the Electrical Diagram Section of this manual.)
Control Transformer (T5) Voltage Test Chart and drawing of transformer and molex plug
(P4), Figure F.14.
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F-45
F-45
TROUBLESHOOTING & REPAIR
CONTROL TRANSFORMER (T5) VOLTAGE TEST (continued)
FIGURE F.13 - LOCATION OF CONTROL BOARD AND CONTROL TRANSFORMER
TEST PROCEDURE
1. Remove input power to the machine.
4. Check for 120VAC at the primary leads
#265 to #266.
2. With the 5/16” nut driver, remove the
machine case top and sides.
A. If 120VAC is present at leads #265 to
#266, go to Step 7.
3. Locate plug J4 on the power board. (Do
not remove.) Also locate the two black sec-
ondary leads. See Figure F.13.
Note: If input voltage varies, the con-
trol transformer voltages will vary
accordingly.
B. If a very low or zero voltage is shown
at leads #265 to #266, go to Step 5.
WARNING
ELECTRIC SHOCK can kill.
5. Remove input power to machine.
• With input power ON,
there are high voltages
inside the machine. Do
not reach into the machine
or touch any internal part
of the machine while
power is on.
3. Turn input power ON.
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F-46
F-46
TROUBLESHOOTING & REPAIR
CONTROL TRANSFORMER (T5) VOLTAGE TEST (continued)
FIGURE F.14 – PLUG P4 DETAILS
BLACK
LEADS
6. Check fuse F1 (0.5 amp). Test the resis-
tance from 6J15, on the feed-thru PC
board, to the #265 lead at the control trans-
former. Also check the resistance from
7J15, on the feed-thru PC board, to the
#266 lead at the control transformer.
IMPORTANT: If the control transformer is
replaced, refer to the label on the new trans-
former for correct primary lead connections. If
connected wrong, the machine will have no
OCV output. If no OCV occurs, reverse the
control transformer primary connections and
recheck machine OCV.
A. If zero ohms resistance is shown, the
test is OK. Proceed to the feed-thru
PC board continuity test.
NOTE: If input voltage varies, control trans-
former voltages will vary accordingly.
B. If resistance of any value is shown,
check wires and connections.
CONTROL TRANSFORMER (T5)
VOLTAGE TEST CHART
7. Test for the correct AC voltages at Plug P4.
See Figure F.14.
Secondary Lead
Colors
Approximate
Plug P4 Pins Voltages
A. If one or more voltages are missing or
incorrect, the control transformer is
faulty. Replace.
Yellow to Yellow
Blue to Blue
White to Blue
Red to White
Red to Red
1 to 2
4 to 6
10VAC
32VAC
16VAC
18VAC
36VAC
B. Also check for 24VAC at the two black
leads going to 1J16 on the feed-thru
PC board and 1J9 on the control PC
board.
5 to 6
10 to 5
10 to 12
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F-47
F-47
TROUBLESHOOTING & REPAIR
CONTROL PC BOARD TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
This test will determine if the correct voltages are being supplied to the control PC board
and if the board is generating the proper signals.
MATERIALS NEEDED
Volt/Ohmmeter (Analog meter recommended)
5/16" Nut driver
Control PC Board Schematic [ G2512 ] (located in the Electrical Diagrams section of this
manual)
Control PC Board Voltage Test Points Chart
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F-48
F-48
TROUBLESHOOTING & REPAIR
CONTROL PC BOARD TEST (continued)
FIGURE F.15 – CONTROL PC BOARD LOCATION
4. Connect the DC voltmeter to the test
points.
TEST PROCEDURE
1. Remove input power to the machine.
WARNING
2. With the 5/16” nut driver, remove the
screws and carefully lower the case front
control panel.
ELECTRIC SHOCK can kill.
3. Locate the test points on the control PC
board that are called out in the Control PC
Board Voltage Test Points Chart. See
Figure F.15 and the Control PC Board
Schematic.
• With input power ON,
there are high voltages
inside the machine. Do
not
reach into
the
machine or touch any
internal part of the
machine while power is
on.
5. Turn on input power to the machine.
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F-49
F-49
TROUBLESHOOTING & REPAIR
CONTROL PC BOARD TEST (continued)
FIGURE F.16 – CONTROL PC BOARD PLUG DETAILS
1
2
3
4
7
5
6
J13
J14
J12
J13
10 9
8
R66
•
R8
•
• • •
R32
R13
R11
G2512-[
]
CONTROL
RESISTOR TEST POINTS
(Control Board Area Enlarged)
PLUG J13 LOCATION
6. Check the test points for the appropriate
voltages. See Figure F.16.
• If the correct voltages are NOT being
applied to the control PC board, the power
PC board or the control transformer may be
faulty.
• If the correct voltages are applied to the
control PC board and the correct voltage
signals are NOT being generated by the
control PC board, the control PC board may
be faulty.
7. After the tests are completed and the prob-
lem repaired, install the front control panel,
using the 5/16” nut driver.
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F-50
F-50
TROUBLESHOOTING & REPAIR
CONTROL PC BOARD TEST (continued)
CONTROL PC BOARD VOLTAGE TEST POINTS CHART
Special
Conditions
for Test
Signals Being
Checked
Expected
Reading
Test Points
3J13 to 5J13
Regulated +15VDC
supply to control
board
+15VDC
None
None
None
4J13 to 5J13
1J13 to 2J13
R11 to 5J13
Regulated -15VDC
supply to control
board
-15VDC
Unregulated DC
supply to control
board
+12VDC
0 - 2 VDC
Low logic signal for
gas/water valve
TIG Mode
Arc Start Switch or
Amptrol must be
activated
R32 to 5J13
R13 to 5J13
Low logic signal for
interlock control
0 - 2 VDC
0 - 2 VDC
If input contactor is
staying closed signal
will normally be low.
Low logic signal
for high frequency
CAUTION: High
frequency may
damage test
equipment.
Use analog
volt/ohmmeter
TIG Mode
High frequency is
active after gas
preflow time.
R66 to 5J13
R8 to 5J13
Low logic signal for
DC OCV Boost
(CR3) relay
0 - 2 VDC
0 - 2 VDC
StickMode
DC Mode
Low logic signal for
AC OCV Boost
(CR2) relay
Stick Mode
AC Mode
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F-51
F-51
TROUBLESHOOTING & REPAIR
STATIC SCR TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
The Static SCR Test is a quick check to determine if an SCR is shorted or “leaky.” See the
machine waveform section for normal and abnormal SCR waveforms.
MATERIALS NEEDED
Analog ohmmeter (Multimeter)
5/16” Nut driver
Machine Wiring Diagrams (See the Electrical Diagrams section of this manual.)
SCR Test Points drawing, Figure F.18.
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F-52
F-52
TROUBLESHOOTING & REPAIR
STATIC SCR TEST (continued)
FIGURE F.17 – POWER PC BOARD PLUG LOCATIONS
4
2
11 10 9
J4
8
3
12
6
10
9
4
8
7
2
6
1
7
G2081-[
]
J2
J6
5
2
3
1
5
4
3
2
1
1
5
3
4
J5
6
7
8
J1
SQUARE WAVE POWER
TEST PROCEDURE
8. With the 1/2” wrench, remove the choke
lead from the negative plate (top).
1. Remove the input power to the machine.
2. With the 5/16” nut driver, remove the
machine case top and sides.
9. With the analog ohmmeter, test the resis-
tance from anode to cathode of SCR1.
Reverse the meter leads and check from
cathode to anode of SCR1.
3. Perform the Input Power Factor Capacitor
Voltage Check and Discharge procedure.
4. Remove the output welding cables from the
machine.
A. If a low resistance is indicated in either
direction, SCR1 is faulty. Replace the
SCR.
5. Remove plug J1 from the power PC board.
Refer to Figure F.17.
10. Repeat Step 9 testing SCR2, SCR3, and
SCR4.
6. Place the polarity switch (S1) in a “DC”
position.
To further check SCR functions, use an
SCR tester and proceed to the Active SCR
test.
7. Remove the red insulating paint from heat
sink test points. See Figure F.18. DO NOT
DISASSEMBLE THE HEAT SINKS.
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F-53
F-53
TROUBLESHOOTING & REPAIR
STATIC SCR TEST (continued)
FIGURE F.18 – SCR TEST POINTS
#3
Cathode
SCR3
SCR 3 & 4 Anode
and Negative Plate
#2
Anode
SCR4
SCR1
#4
Cathode
SCR1 & 2 Cathode
and Positive Plate
Choke
Lead
#1
Anode
SCR2
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F-54
F-54
TROUBLESHOOTING & REPAIR
ACTIVE SCR TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
TEST DESCRIPTION
The Active SCR Test will determine if the device is able to be gated “ON” and conduct cur-
rent from anode to cathode.
MATERIALS NEEDED
An SCR tester as outlined in this procedure
5/16” Nut driver
Machine Wiring Diagrams (See Electrical Diagrams section of this manual.)
SCR Test Points drawing, Figure F.20.
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F-55
F-55
TROUBLESHOOTING & REPAIR
ACTIVE SCR TEST (continued)
FIGURE F.19 - POWER BOARD PLUG LOCATIONS
G2081-[
]
SQUARE WAVE POWER
TEST PROCEDURE
1. Remove the input power to the machine.
7. Remove the red insulating paint from heat
sink test points. See Figure F.20. DO
NOT DISASSEMBLE THE HEAT SINKS.
2. With the 5/16” nut driver, remove the
machine case top and sides.
8. With the 1/2” wrench, remove the choke
lead from the negative plate (top).
3. Perform the Input Power Factor Capacitor
Voltage Check and Discharge procedure.
9. Perform the test procedure as outlined in
Figure F.21. Repeat the test for all four
SCRs.
4. Remove the output welding cables from the
machine.
5. Remove plug J1 from the power PC board.
See Figure F.19.
10. Replace any SCR or SCR assembly that
does not pass the test in Step 9.
6. Place the polarity switch (S1) in a “DC”
position.
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F-56
F-56
TROUBLESHOOTING & REPAIR
ACTIVE SCR TEST (continued)
FIGURE F.20 – SCR TEST POINTS
#3
Cathode
SCR3
SCR 3 & 4 Anode
and Negative Plate
#2
Anode
SCR4
SCR1
#4
Cathode
SCR1 & 2 Cathode
and Positive Plate
Choke
Lead
#1
Anode
SCR2
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F-57
F-57
TROUBLESHOOTING & REPAIR
ACTIVE SCR TEST (continued)
FIGURE F.21 - SILICON CONTROLLED RECTIFIER TEST SETUP.
To test SCRs construct the circuit outlined above.
Resistor values are plus or minus ten percent. The
voltmeter scale should be low, approximately 0-5 or
0-10 volts DC.
1. Connect the SCR into the test circuit as
shown: (A) lead to anode, (C) lead to cath-
ode, and (G) lead to the gate. NOTE: the
gate leads are located in plug J1.
SILICON CONTROLLED
RECTIFIER TEST
(Heat Sink Mounted Units)
To test the SCRs, construct the circuit outlined
in Figure F.21. One 6V lantern battery can be
used. Resistor tolerances are 10%. The volt-
meter scale should be low, approximately 0-5
or 0-10 volts.
2. Close switch SW-1 (switch SW-2 should be
open). The voltmeter should read zero. If
the voltmeter reads higher than zero, the
SCR is shorted.
3. With switch SW-1 closed, close switch SW-
2 for two seconds and release. The volt-
meter should read 3 to 6 volts before and
after switch SW-2 is released. If the volt-
meter does not read, or reads only while
SW-2 is depressed, the SCR or battery is
defective. (Repeat Battery Test Procedure)
BATTERY TEST
Check the battery by shorting leads (A) and (C)
and then close switch SW-1. Replace the bat-
tery if the voltage is less than 4.5 volts.
4. Open switch SW-1, disconnect the gate
lead (G), and reverse the (A) and (C) leads
on the SCR. Close switch SW-1. The volt-
meter should read zero. If the voltage is
higher than zero, the SCR is shorted.
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F-58
F-58
TROUBLESHOOTING & REPAIR
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM
DC STICK MODE
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
CH1
0 volts
2 ms
50 volts
This is the typical DC (+) output volt-
age waveform generated from a
properly operating machine. Note
that each vertical division represents
50 volts and that each horizontal divi-
sion represents 2 milliseconds in
time.
Note: Scope probes connected at
machine output terminals: (+) probe
to electrode terminal, (-) probe to
work terminal.
SCOPE SETTINGS
Volts/Div.....................50V/Div.
Horizontal Sweep.....2 ms/Div.
Coupling ............................DC
Trigger .........................Internal
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F-59
F-59
TROUBLESHOOTING & REPAIR
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM
AC STICK MODE
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
CH1
0 volts
2 ms
50 volts
This is the typical AC output voltage
waveform generated from a properly
operating machine. Note that each
vertical division represents 50 volts
and that each horizontal division rep-
resents 2 milliseconds in time.
Note: Scope probes connected at
machine output terminals: (+) probe
to electrode terminal, (-) probe to
work terminal.
SCOPE SETTINGS
Volts/Div.....................50V/Div.
Horizontal Sweep.....2 ms/Div.
Coupling ............................DC
Trigger .........................Internal
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F-60
F-60
TROUBLESHOOTING & REPAIR
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM
DC TIG MODE
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
CH1
0 volts
2 ms
50 volts
This is the typical DC (+) output volt-
age waveform generated from a
properly operating machine. Note
that each vertical division represents
50 volts and that each horizontal divi-
sion represents 2 milliseconds in
time.
Note: Scope probes connected at
machine output terminals: (+) probe
to electrode terminal, (-) probe to
work terminal.
SCOPE SETTINGS
Volts/Div.....................50V/Div.
Horizontal Sweep.....2 ms/Div.
Coupling ............................DC
Trigger .........................Internal
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F-61
F-61
TROUBLESHOOTING & REPAIR
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM
AC TIG MODE
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
CH1
0 volts
2 ms
50 volts
This is the typical AC output voltage
waveform generated from a properly
operating machine. Note that each
vertical division represents 50 volts
and that each horizontal division rep-
resents 2 milliseconds in time.
Note: Scope probes connected at
machine output terminals: (+) probe
to electrode terminal, (-) probe to
work terminal.
SCOPE SETTINGS
Volts/Div.....................50V/Div.
Horizontal Sweep.....2 ms/Div.
Coupling ............................DC
Trigger .........................Internal
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F-62
F-62
TROUBLESHOOTING & REPAIR
TYPICAL OUTPUT VOLTAGE WAVEFORM – MACHINE LOADED
DC TIG MODE
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
CH1
0 volts
2 ms
20 volts
MACHINE LOADED TO 350 AMPS
AT 34VDC
This is a typical DC (+) output voltage
waveform generated from a properly
operating machine. Note that each
vertical division represents 20 volts
and that each horizontal division rep-
resents 2 milliseconds in time. The
machine was loaded with a resis-
tance grid bank. The TIG 355 display
read 350 amps at 34 VDC.
Note: Scope probes connected at
machine output terminals: (+) probe
to electrode terminal, (-) probe to
work terminal.
SCOPE SETTINGS
Volts/Div.....................20V/Div.
Horizontal Sweep.....2 ms/Div.
Coupling ............................DC
Trigger .........................Internal
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F-63
F-63
TROUBLESHOOTING & REPAIR
AC TIG MODE (BALANCED WAVEFORM)
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
CH1
0 volts
2 ms
20 volts
MACHINE LOADED TO 350 AMPS
AT 34VAC
This is a typical AC output voltage
waveform generated from a properly
operating machine. Note that each
vertical division represents 20 volts
and that each horizontal division rep-
resents 2 milliseconds in time. The
machine was loaded with a resis-
tance grid bank. The TIG 355 display
read 350 amps at 34 VAC.
Note: Scope probes connected at
machine output terminals: (+) probe
to electrode terminal, (-) probe to
work terminal.
SCOPE SETTINGS
Volts/Div.....................20V/Div.
Horizontal Sweep.....2 ms/Div.
Coupling ............................DC
Trigger .........................Internal
8/98
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F-64
F-64
TROUBLESHOOTING & REPAIR
ABNORMAL OPEN CIRCUIT VOLTAGE – DC TIG MODE
ONE OUTPUT SCR NOT FUNCTIONING
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
CH1
0 volts
2 ms
50 volts
This is NOT the typical DC (+) output
voltage waveform. One output SCR
is not functioning. Note the “gap” in
the waveform. One SCR gate was
disconnected to simulate an open or
non-functioning output SCR. Each
vertical division represents 50 volts
and each horizontal division repre-
sents 2 milliseconds in time.
Note: Scope probes connected at
machine output terminals: (+) probe
to electrode terminal, (-) probe to
work terminal.
SCOPE SETTINGS
Volts/Div.....................50V/Div.
Horizontal Sweep.....2 ms/Div.
Coupling ............................DC
Trigger .........................Internal
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F-65
F-65
TROUBLESHOOTING & REPAIR
ABNORMAL OPEN CIRCUIT VOLTAGE – AC TIG MODE
ONE OUTPUT SCR NOT FUNCTIONING
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
CH1
0 volts
2 ms
50 volts
This is NOT the typical AC output
voltage waveform. One output SCR
is not functioning. Note the “gap” in
the waveform. One SCR gate was
disconnected to simulate an open or
non-functioning output SCR. Each
vertical division represents 50 volts
and each horizontal division repre-
sents 2 milliseconds in time.
Note: Scope probes connected at
machine output terminals: (+) probe
to electrode terminal, (-) probe to
work terminal.
SCOPE SETTINGS
Volts/Div.....................50V/Div.
Horizontal Sweep.....2 ms/Div.
Coupling ............................DC
Trigger .........................Internal
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F-66
F-66
TROUBLESHOOTING & REPAIR
CONTROL PC BOARD REMOVAL AND REPLACEMENT
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
DESCRIPTION
The following procedure will aid the technician in removing the control PC board.
MATERIALS NEEDED
5/16" Nut driver
Phillips head screw driver
Static grounding wrist strap
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F-67
F-67
TROUBLESHOOTING & REPAIR
CONTROL PC BOARD REMOVAL AND REPLACEMENT (continued)
FIGURE F.22 - CONTROL PC BOARD
J8
J9
J10
J12
J13
J14
J11
SQUARE WAVE 355 CONTROL
G2081-[
]
TEST PROCEDURE
CAUTION
Before starting the following procedure, refer
to the topic "PC Board Troubleshooting
Procedures" at the beginning of this section.
Be sure to follow the recommended static-free
methods for handling printed circuit boards.
Failure to do so can result in permanent dam-
age to the equipment.
1. Remove input power to the machine.
2. With the 5/16" nut driver, remove the sheet
metal screws that hold the front control
panel in place. Carefully lower the panel.
6. Replace the old control PC board. Mount
the board with the mounting screws and
phillips head screw driver.
3. Carefully remove the molex type plugs con-
nected to the control PC board. See Figure
F.22.
7. Carefully install the molex plugs that con-
nect to the control PC board.
4. With the phillips head screw driver, remove
the mounting screws from the control PC
board.
8. Replace the front control panel and tighten
the sheet metal screws with the 5/16" nut
driver.
5. Carefully remove the control PC board. Be
sure to observe static electricity cautions.
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F-68
F-68
TROUBLESHOOTING & REPAIR
POWER PC BOARD REMOVAL AND REPLACEMENT
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
DESCRIPTION
The following procedure will aid the technician in removing the power PC board.
MATERIALS NEEDED
5/16" Nut driver
Phillips head screw driver
Static grounding wrist strap
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F-69
F-69
TROUBLESHOOTING & REPAIR
POWER PC BOARD REMOVAL AND REPLACEMENT (continued)
FIGURE F.23 - POWER PC BOARD
4
2
11 10 9
J4
8
3
12
6
10
9
4
8
7
2
6
1
7
G2081-[
]
J2
J6
5
2
3
1
5
4
3
2
1
1
5
3
4
J5
6
7
8
SQUARE WAVE POWER
PROCEDURE
CAUTION
Before starting the following procedure, refer
to the topic "PC Board Troubleshooting
Procedures" at the beginning of this section.
Be sure to follow the recommended static-free
methods for handling printed circuit boards.
Failure to do so can result in permanent dam-
age to the equipment.
1. Remove input power to the machine.
2. With the 5/16" nut driver, remove the sheet
metal screws that hold the front control
panel in place. Carefully lower the panel.
3. Carefully remove the 6 molex type plugs
connected to the power PC board. See
Figure F.23.
6. Replace the old power PC board. Mount
the board with the 6 mounting screws and
phillips head screw driver.
4. With the phillips head screw driver, remove
the 6 mounting screws from the power PC
board.
7. Carefully install the 6 molex plugs that con-
nect to the power PC board.
8. Replace the front control panel and tighten
the sheet metal screws with the 5/16" nut
driver.
5. Carefully remove the power PC board. Be
sure to observe static electricity cautions.
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F-70
F-70
TROUBLESHOOTING & REPAIR
INPUT CONTACTOR REMOVAL AND REPLACEMENT
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
DESCRIPTION
The following procedure will aid the technician in removing the input contactor (C1) for main-
tenance or replacement.
MATERIALS NEEDED
5/16" Nut driver
Slot head screw driver
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F-71
F-71
TROUBLESHOOTING & REPAIR
INPUT CONTACTOR REMOVAL AND REPLACEMENT (continued)
FIGURE F.24 – INPUT CONTACTOR CONNECTIONS
PROCEDURE
1. Remove input power to the machine.
7. Remove small lead H1 from the L1 termi-
nal.
2. With the 5/16" nut driver, remove the case
top and sides.
8. Remove small lead #246 from the L2 ter-
minal.
3. Perform the Input Power Factor Capacitor
Voltage Check.
9. Remove leads #243 and #244 from the
contactor coil tabs.
4. With the 5/16" nut driver, remove the rear
access panel.
10. Remove leads #243 and #242 from the
contactor interlock located on the bottom
of the contactor.
For Steps 5-20, refer to Figure F.24.
5. With the slot head screw driver, remove the
input leads from the L1 and L2 terminals on
the input contactor.
11. With the 5/16" nut driver, remove the 4
screws mounting the contactor bracket to
the case back.
6. With the slot head screw driver, remove the
copper strap, the heavy lead, and the small
capacitors from the output side of the con-
tactor.
12. Carefully remove the contactor and the
bracket assembly from the case back.
.
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F-72
F-72
TROUBLESHOOTING & REPAIR
INPUT CONTACTOR REMOVAL AND REPLACEMENT (continued)
13. Replacement: Mount the contactor brack-
et assembly to the case back and attach it
with the 4 mounting screws. Use the
5/16" nut driver.
14. Attach leads #243 and #242 to the con-
tactor interlock located on the bottom of
the contactor.
15. Attach leads #243 and #244 to the con-
tactor coil tabs.
16. Attach small lead #246 to the L2 terminal.
17. Attach small lead H1 to the L1 terminal.
18. With the slot head screw driver, attach the
copper strap, the heavy lead, and the
small capacitors to the output side of the
contactor.
19. With the slot head screw driver, attach the
input leads to the L1 and L2 terminals on
the input contactor.
20. With the 5/16" nut driver, install the rear
access panel, case sides and top.
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F-73
F-73
TROUBLESHOOTING & REPAIR
FAN MOTOR AND BLADE REMOVAL AND REPLACEMENT
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
DESCRIPTION
The following procedure will aid the technician in accessing and removing the fan motors
and blades for maintenance or replacement.
MATERIALS NEEDED
5/16" Nut driver
1/4" Nut driver
11/32" Wrench
Diagonal cutters
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F-74
F-74
TROUBLESHOOTING & REPAIR
FAN MOTOR AND BLADE REMOVAL AND REPLACEMENT (continued)
FIGURE F.25- FAN MOTOR AND BLADE MOUNTING DETAILS
PROCEDURE
The following procedure allows you to remove
and replace either of the two fans on the
Square Wave TIG 355.
NOTE: You may have to loosen or remove the
bottom case back screws to gain enough
clearance to remove the motor.
1. Remove the input power to the machine.
8. Replacement: Mount the fan motor to the
fan bracket with the flat washers, lock
washers, and nuts removed earlier. Use
the 11/32" wrench.
2. With the 5/16" nut driver, remove the case
top and sides.
3. Perform the Input Power Factor Capacitor
Voltage Check.
9. Slide the fan blade onto the fan motor
shaft. Note its proper placement. With
the 1/4" nut driver, tighten the fan blade
clamp.
For Steps 4-11, refer to Figure F.25.
4. With the 1/4" nut driver, loosen the fan
blade clamp and slide the blade from the
motor shaft. Note blade placement on the
shaft for reassembly.
10. Splice or resolder any wires cut during
removal. Insulate connectors. Replace
cable ties as necessary.
5. With the 11/32" wrench, remove the nuts,
lock washers, and flat washers that mount
the fan motor to the fan bracket.
11. With the 5/16" nut driver, install the case
top and sides.
6. Cut any cable ties or wire leads.
7. Carefully remove the fan motor from the fan
bracket.
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F-75
F-75
TROUBLESHOOTING & REPAIR
OUTPUT RECTIFIER REMOVAL AND REPLACEMENT
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
DESCRIPTION
The following procedure will aid the technician in removing the output rectifier for mainte-
nance or replacement.
MATERIALS NEEDED
5/16" Nut driver
1/2" Wrench
7/16" Wrench
Diagonal cutters
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F-76
F-76
TROUBLESHOOTING & REPAIR
OUTPUT RECTIFIER REMOVAL AND REPLACEMENT (continued)
FIGURE F.26 – OUTPUT RECTIFIER CONNECTION DETAILS
Step 13
Step 11
Step 12
Step 10
Step 7
Step 5
Step 9
Step 6
Step 15
Step 8
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F-77
F-77
TROUBLESHOOTING & REPAIR
OUTPUT RECTIFIER REMOVAL AND REPLACEMENT (continued)
15. With the 7/16" wrench, remove the four
nuts, lock washers, and two flat washers
mounting the rectifier assembly to the
main transformer iron. NOTE: The two flat
washers are located on the right hand
mounting screws.
PROCEDURE
1. Remove input power to the machine.
2. With the 5/16" nut driver, remove the case
top and sides.
3. Perform the Input Power Factor Capacitor
Voltage Check.
16. Carefully remove the rectifier, snubber,
and torriod assembly.
For Steps 4-27, refer to Figure F.26.
17. Reassembly: carefully mount the rectifier,
snubber, and torriod assembly onto the
main transformer iron. With the 7/16"
wrench, fasten the assembly down with
the flat washers, lock washers, and nuts.
Note that the two flat washers are located
on the the right hand mounting screws.
4. Remove plug J1 from the power PC board.
5. With the 1/2" wrench, remove the choke
lead from the negative plate.
6. With the 1/2" wrench, remove the X1 lead
from SCR1 - SCR4 junction. Note lead
placement for reassembly: X1 is sand-
wiched between the two leads from the
output rectifier bridge.
18. Attach lead #212 to the R3 resistor.
(Splice or solder the connection.)
19. Route leads #213 and #214/214A and
attach them to the background rectifier.
Replace any necessary cable ties.
7. With the 1/2" wrench, remove the lead at
the SCR2 - SCR3 junction leading to the
polarity switch (S1). Note lead placement
for reassembly.
20. Attach leads #215 and #264 to the R7
resistor.
8. With the 1/2" wrench, remove the lead
from the positive plate leading to the
polarity switch (S1).
21. With the 7/16" wrench, attach D1, D2 and
the copper strap lead assembly to the
insulated stud on the negative plate.
Attach the small lead from the CR3 relay
to the negative plate.
9. With the 7/16" wrench, remove the small
lead from the negative plate leading to
CR3 relay.
22. With the 1/2" wrench, attach the lead from
the polarity switch (S1) to the positive
plate.
10. With the 7/16" wrench, remove D1, D2
and the copper strap lead assembly from
the insulated stud on the negative plate.
23. With the 1/2" wrench, attach the lead from
the polarity switch (S1) at the SCR2 -
SCR3 junction.
11. Remove leads #215 and #264 from the R7
resistor.
12. Remove leads #213 and #214/214A from
the background rectifier. Separate leads
#214 and #214A and pull them through.
Cut any necessary cable ties.
24. With the 1/2" wrench, attach the X1 lead
to the SCR1 - SCR4 junction. X1 is sand-
wiched between the two leads from the
output rectifier bridge.
13. Remove (cut or unsolder) lead #212 from
the R3 resistor.
25. With the 1/2" wrench, attach the choke
lead to the negative plate.
14. Remove leads #210 and #211 from plug
J1 (Located at power board. See wiring
diagram). Use a molex pin extractor. Note
lead placement for reassembly.
26. Attach plug J1 to the power PC board.
27. With the 5/16" nut driver, install the case
top and sides.
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F-78
F-78
TROUBLESHOOTING & REPAIR
SCR REMOVAL AND AND REPLACEMENT
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-
trical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).
DESCRIPTION
The following procedure will aid the technician in removing the SCRs from the output rectifi-
er heat sink asssembly for maintenance or replacement.
MATERIALS NEEDED
5/16" nut driver
1/2" Wrench
7/16" Wrench
Diagonal cutters
1/4" socket or box end wrench
Putty knife
Fine steel wool (No. 000)
Heat sink compound, Lincoln Electric #E2529 (Penetrox A-13 or Penetrox A)
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F-79
F-79
TROUBLESHOOTING & REPAIR
SCR REMOVAL AND AND REPLACEMENT (continued)
SPECIAL INSTRUCTIONS
Before disassembling the output rectifier, note
which heat sink the outer metal ring of the
power SCR is mounted toward. Also note the
positioning of the gate lead of the SCR. Failure
to reinstall the new SCR in the same orienta-
tion as the original may result in subsequent
damage to the new SCR and other compo-
nents of the welder. See Figure F.27.
FIGURE F.27 - SCR DETAILS
4. With a puffy knife or similar tool, clean the
area on the heat sink around the SCR
mounting surface. DO NOT SCRATCH THE
SCR MOUNTING SURFACE.
CAUTION
The unclamping and clamping procedure out-
lined below is critical for the prevention of iner-
nal SCR damage. Failure to follow this proce-
dure may result in subsequent damage of the
SCR. Handle all SCRs with care.
5. Polish each heat sink’s mounting surface
using No. 000 fine steel wool. Wipe the
surface clean with a lint-free cloth or paper
towel.
6. Inspect the mounting surfaces of each new
SCR. Remove all burrs and wipe clean. Do
not use steel wool or any abrasive cleanser
on the SCR mounting surfaces.
PROCEDURE
1. Perform the Output Rectifier Removal
and Replacement procedure.
7. Apply a thin (0.001” to 0.003”) layer of PEN-
ETROX A-13 (Lincoln Electric #E2529) or
PENETROX A, heat sink compound, to
each heat sink’s SCR mounting surface.
Use care to prevent foreign material conta-
mination of the SCR-to-heat sink junction.
2. With the 1/2” wrench, alternately loosen the
heat sink nuts 1/2 turn each until the heat
sinks are loose. Remove the nuts and leaf
spring. IT IS RECOMMENDED THAT NEW
HARDWARE, LEAF SPRING AND HOUS-
ING BE USED FOR REASSEMBLY.
3. Remove the old SCR.
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F-80
F-80
TROUBLESHOOTING & REPAIR
SCR REMOVAL AND AND REPLACEMENT (continued)
8. Place the new SCR betwen the heat sinks.
Be sure that the outer metal ring of the
SCR is facing toward the same heat sink
as the old SCR’s metal ring. Be sure that
the roll pin of the heat sink engages the
“hole” in the SCR. The SCR contact sur-
faces must sit flat against both heat sink
surfaces.
A. PROCEDURE FOR THE 1/2 INCH
WIDE SPRING:
1) Place a piece of sleeving around
each cap screw.
2) Insert the cap screws through the
leaf spring. Orient the leaf spring
so that its ends are curved upward
toward the cap screw heads. See
Figure F.28. Pressing on the cap
screw heads should produce a
“rocking” motion of the spring in
its housing. If the spring does
NOT rock, it is installed upside
down. Remove the spring and
turn it over. Check for “rocking”
motion.
9. Clamp the SCRs to the output rectifier
heat sink assembly.
10. Two different designs of leaf springs and
housings have been used to clamp the
SCR to the rectifier. The two different
designs can be identified by the size of the
leaf spring. One design uses a 1/2” wide
leaf spring and the other uses a 5/8” wide
spring. Follow procedure A below for 1/2”
springs. Follow procedure B for 5/8”
springs.
3) Insert the cap screws and leaf
spring into the plastic housing.
4) Insert clamp assembly through the
11. The different designs require different
assembly and clamping procedures,
depending upon the thread on the cap
screws. A 1/4-28 thread requires a differ-
ent tightening procedure than a 1/4-20
thread. NOTE WHICH THREAD IS ON
YOUR CAP SCREWS BEFORE PER-
FORMING THE ASSEMBLY PROCEDURE.
heat sinks.
Install the nuts.
Tighten the clamp nuts equally on
the cap screws until finger tight.
(See Figure F.29.)
FIGURE F.28 – 1/2” WIDE LEAF SPRING
Spring curvature exaggerated
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F-81
F-81
TROUBLESHOOTING & REPAIR
SCR REMOVAL AND AND REPLACEMENT (continued)
FIGURE F.29 – SCR CLAMP ASSEMBLY DETAILS – 1/2” WIDE SPRING
Cap Screw
Plastic Housing
Leaf Spring
Heat Sink
SCR
Heat Sink
Plain Washer
Clamp Nut
5) Re-inspect the SCR for proper
seating.
f. Tighten first cap screw 1/4
turn. Stop. The assembly
now has proper clamping
force.
6) Clamp the cap screws. Use the
procedure for 1/4-28 cap screws
or 1/4-20 bolts, depending on
which you have.
Clamping procedure for 1/4-20 cap screws.
NOTE: This procedure can only be used
with 1/4-20 cap screws. Do not
use cap screws with any other
type thread, or the new SCR will
be damaged. Do not overtighten
the cap screws. The leaf spring
will apply the required clamping
force to the SCR.
Clamping procedure for 1/4-28 cap
screws.
NOTE: This procedure can only be
used with 1/4-28 bolts. Do not use
bolts with any other type thread, or the
new SCR will be damaged. Do not
overtighten the cap screws. The leaf
spring will apply the required clamping
force to the SCR.
a. Do not turn the nuts. While
holding the nuts stationary,
turn the cap screws only with
the following procedure.
a. Do not turn the nuts. While
holding the nuts stationary,
turn the bolts only with the fol-
lowing procedure.
b. Tighten first cap screw 1/4
turn.
b. Tighten first cap screw 1/4
turn.
c. Tighten second cap screw 1/2
turn.
c. Tighten second cap screw 1/2
turn.
d. Tighten first cap screw 1/2
turn.
d. Tighten first cap screw 1/2
turn.
e. Tighten second cap screw 1/4
turn. Stop. The assembly
now has the proper clamping
force.
e. Tighten second cap screw 1/2
turn.
7) Perform the Active SCR Test.
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F-82
F-82
TROUBLESHOOTING & REPAIR
SCR REMOVAL AND AND REPLACEMENT (continued)
FIGURE F.30 – HOUSING AND PRESSURE PAD FOR 5/8” WIDE LEAF SPRING
Steel Pressure Pad
Housing
B. PROCEDURE FOR THE 5/8 INCH
WIDE SPRING:
Clamping procedure for 1/4-28 cap
screws. Note: This procedure can only
be used with 1/4-28 cap screws. Do
not use cap screws with any other type
thread, or the new SCR will be dam-
aged. Do not overtighten the cap
screws. The leaf spring will apply the
required clamping force to the SCR.
1) Place a piece of sleeving around
each cap screw.
2) Insert the cap screws through the
leaf spring. The leaf spring is flat
so the orientation of the leaf spring
does not matter.
a. Do not turn the nuts. While
holding the nuts stationary,
turn the cap screws only with
the following procedure.
3) Place the steel pressure pad in the
housing with the 1/8” wide standoff
facing up. See Figure 30.
4) Insert the cap screws and leaf
spring into the plastic housing. Be
sure that the steel pressure pad
remains in position. Pressing on
the cap screw heads should pro-
duce a rocking action of the spring
in its housing.
b. Tighten first cap screw 1/4
turn.
c. Tighten second cap screw 1/2
turn.
d. Tighten first cap screw 1/2
turn.
5) Insert the clamp assembly through
the heat sinks. Install the nuts.
Tighten the clamp nuts equally on
the cap screws until finger tight.
Be sure that the leaf spring is not
cocked in the housing. See Figure
31.
e. Tighten second cap screw 1/2
turn.
f. Tighten first cap screw 1/2
turn.
g. Tighten second cap screw 1/4
turn. Stop. The assembly now
has the proper clamping force.
6) Re-inspect the SCR for proper
seating.
7) Clamp the cap screws. Use the
procedure for 1/4-28 cap screws or
1/4-20 cap screws, depending on
which you have.
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F-83
F-83
TROUBLESHOOTING & REPAIR
SCR REMOVAL AND AND REPLACEMENT (continued)
FIGURE F.31 – SCR CLAMP ASSEMBLY DETAILS – 5/8” WIDE SPRING
Cap Screw
Steel Pressure Pad
Leaf Spring
Plastic Housing
Heat Sink
SCR
Heat Sink
Plain Washer
Clamp Nut
Clamping procedure for 1/4-20 cap
screws. Note: This procedure can only
be used with 1/4-20 cap screws. Do
not use cap screws with any other
type thread, or the new SCR will be
damaged. Do not overtighten the cap
screws. The leaf spring will apply the
required clamping force to the SCR.
e. Tighten the second cap screw
1/4 turn.
f. Tighten the first cap screw 1/8
turn.
g. Tighten the second cap screw
1/8 turn. Stop. The assembly
now has the proper clamping
force.
a. Do not turn the nuts. While
holding the nuts stationary,
turn the cap screws only with
the following procedure.
8) Perform the Active SCR Test.
10. Install the output rectifier heat sink assem-
bly back into the machine. See Output
Rectifier Removal and Replacement in
this section of the manual.
b. Tighten first cap screw 1/4
turn.
c. Tighten second cap screw 1/2
turn.
d. Tighten the first cap screw 1/2
turn.
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F-84
F-84
TROUBLESHOOTING & REPAIR
RETEST AFTER REPAIR
Retest a machine:
• If it is rejected under test for any reason that requires you to remove any mechanical part
which could affect the machine’s electrical characteristics.
OR
• If you repair or replace any electrical components.
NOTE: 50 Hz machines may be tested using 60 Hz power.
INPUT AMPS AT RATED MACHINE OUTPUT
Input Volts/Hertz
Load Amps
208/60
230/60
460/60
575/60
110
100
50
40
200/50
220/50
380/50
440/50
115
104
61
52
INPUT IDLE AMPS
Input Volts/Hertz
230/60
Maximum Idle Amps
62
50
220/50
NOTE: Power factor correction capacitors are standard on all models. The capacitors
cause high idle currents, but idle power is low.
OPEN CIRCUIT VOLTAGES
Stick Mode OCV
TIG Mode OCV
AC 60-70
DC 60-70
AC 60-70
DC 60-70
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F-85
F-85
TROUBLESHOOTING & REPAIR
RETEST AFTER REPAIR (continued)
OUTPUT CURRENT RANGE
2 - 400 Amps AC and DC
RECOMMENDED METERS FOR MACHINE OUTPUT TESTS
VOLTMETER:
AMMETER:
AC and DC True RMS Meter – Fluke 8922A or equivalent
Columbia Type AX AC or DC Tong Ammeter
IMPORTANT: IF OTHER TYPE METERS ARE USED RESULTS MAY NOT BE ACCURATE
FIGURE F32. – TRANSFORMER LEAD TEST POINTS
X5
X6
X1
X2
X7
X3
X4
MAIN TRANSFORMER SECONDARY VOLTAGES (SEE FIGURE F32)
Test Points
X1 to X2
X3 to X4
X5 to X6
X2 to X7
Voltages
84 to 89VAC
117 to 125VAC
22 to 24VAC
77 to 81VAC
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G-1
G-1
TABLE OF CONTENTS
- ELECTRICAL DIAGRAMS SECTION -
Electrical Diagram Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section G
Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-2
Machine Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-3
Meter PC Board (M15893) Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . G-4
Feed Through PC Board (L8096) Schematic . . . . . . . . . . . . . . . . . . . . . G-5
Protection PC Board (M16062) Schematic . . . . . . . . . . . . . . . . . . . . . . . G-6
Power PC Board (G2081) Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . G-7
Control PC Board (G2512) Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . G-8
Protection PC Board (M16062) Layout . . . . . . . . . . . . . . . . . . . . . . . . . . G-9
Power PC Board (G2081) Layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-10
Bypass PC Board (M15299) Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-11
Feed Through PC Board (L8096) Layout . . . . . . . . . . . . . . . . . . . . . . . . G-12
Control PC Board (G2512) Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-13
Meter PC Board (M15893) Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-14
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NOTES
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G-2
G-2
ELECTRICAL DIAGRAMS
Wiring Diagram
2 5 1 G 9
SINGLE VOLTAGE MACHINE
DUAL VOLTAGE MACHINE
TO GROUND PER NATIONAL ELECTRIC CODE
4
STEP
STEP
STICK
TIG
CONTINUOUS
LOCAL
START
REMOTE
304
302
303
301
OFF
2
HIGH
CURRENT
CONTROL
FREQUENCY
MODE
S11
2
STEP/4 STEP
S19
S10
S12
UNLESS OTHERWISE SPECIFIED TOLERANCE
ON HOLE SIZES PER E2056
THIS SHEET CONTAINS PROPRIETARY INFORMATION
EQUIP.
TYPE
SQUARE WAVE TIG 355
WIRING DIAGRAM
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
OWNED BY
AND IS
5-8-92E
5-14-93F
3-4-94A
THE LINCOLN ELECTRIC CO.
ON
ON
2
3
PLACE DECIMALS IS .02
PLACE DECIMALS IS .002
NOT TO BE REPRODUCED, DISCLOSED OR USED
WITHOUT THE EXPRESS PERMISSION OF
SUBJECT
ON ALL ANGLES IS .5 OF
MATERIAL TOLERANCE (" ") TO AGREE
A
DEGREE
SCALE
NONE
t
SHT.
NO.
THE LINCOLN ELECTRIC CO.
G2097
JJJ
4-2-92
REF.
2519
DR
DATE
CHK
SUP'S'D'G
WITH PUBLISHED STANDARDS.
G
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The specific diagram for a particular code is pasted inside the machine on one of the enclosure panels.
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G-3
G-3
ELECTRICAL DIAGRAMS
Machine Schematic
2 5 2 G 2
L8
THERMOSTAT
TOROID
PRIMARY
MAIN
TRANSFORMER
T1
PRIMARY THERMOSTAT
PRIMARY THERMOSTAT
4J1
8J1
210
211
THERMOSTAT
(+)5
V
1J12
2J12
3J12
4J12
301
302
303
304
301
302
303
304
2J7
4J7
1J7
3J7
C9
C10
COMMON
DATA
RECONNECT
PANEL
BACKGROUND RECTIFIER (+)
BACKGROUND RECTIFIER (-)
BACKGROUND
RECTIFIER
X5
6J1
5J1
213
214
CLOCK
.0047/
3KV
-
H4
CR1
CR1
+
L2
L1
X6
X1
H3
H2
BRIDGE TOROID
BACKGROUND RECTIFIER (-)
MAIN RECTIFIER AC
SCR4 GATE
B.G. TRANSISTOR
B.G. TRANSISTOR
SCR1 GATE
214A
216A
G4
214
215A
G1
220
G2
219
218A
G3
OCV BOOST
RECTIFIER
UNREG. TO (+)
UNREG. TO COMMON ON CONTROL BOARD
(+) 15
(-) 15
PWR SUPPLY GND. TO CONTROL BRD. COMMON
AC SYNC
5
V
REGULATOR ON CONTROL BOARD
SCR1 GATE
1J2
2J2
3J2
4J2
5J2
6J2
2J1
13J1
G1
G2
G3
G4
1J13
2J13
3J13
4J13
5J13
6J13
G1
G2
SCR2 GATE
V
V
SCR3 GATE
Q1
BACKGROUND TRANSISTOR
X7
X2
9J1
G3
SCR1
SCR4
SCR4 GATE
1
2J1
G4
}
B.G. TRANS.
MAIN RECT. AC
MAIN RECT. AC
+
-
7J1
264
216
217
R7
215
216
217
218
H1
MAIN RECTIFIER (-)
SCR2 GATE
MAIN
11J1
1J1
+
-
100/25
RECTIFIER
D1
150
GAS (& WATER) VALVE CONTROL
MAIN RECT.
+
8J13
9J13
10J13
8J2
9J2
10J2
3J1
218
RECONNECT
PANEL
HIGH FREQ. CONTROL
BACKGROUND RESISTOR
MAIN RECTIFIER (+)
SCR3 GATE
MAIN RECTIFIER AC
*
SCR3
14J1
212
/400
INTERLOCK CONTROL (OVER VOLTAGE SHUTDOWN)
*
SCR2
*
217A
PENETRATION SCR CONTROL
CLEANING SCR CONTROL
1J5
2J5
3J5
4J5
5J5
6J5
7J5
1J14
2J14
3J14
4J14
5J14
6J14
7J14
D2
400
POWER
FACTOR
CORR.
*
R3
CR2
CR3
SCR GROUND (TO GND ON*POWER BRD)
BACKGROUND COMMAND
T5
10/
AC OCV BOOST
8/ 100
1J4
2J4
10J4
4J4
Y
Y
R
U
7J17
6J17
6J18
256
255
258
257
CR2
CR3
BACKGROUND GROUND
OUTPUT
INDUCTOR
265
6J15
7J15
H2
H3
L3
H1
H4
DC OCV BOOST RELAY (CR3) CONTROL
PILOT
AC OCV BOOST RELAY (CR2) CONTROL
CR2
*
115V
DC
T2
DC OCV BOOST
*
TRANSFORMER
CR3
232
5J4
W
250
SEE NOTE
X1
X2
6J4
U
266
A
*
12J4
R
115 VAC
B
B
CONTROL TRANSFORMER
DC MODE
24 VAC
AC
223
DC
+
AC
204C
AC RELAY
DC RELAY
115 VAC TO TRIAC CIRCUITS
REMOTE
RECEPTACLE
5J3
6J3
1J6
1J3
3J3
4J3
2J3
267
268
269
270
271
272
273
267
268
269
270
271
272
273
5J15
4J15
1J15
10J1
2J15
9J15
8J15
SECONDARY
THERMOSTAT
POT HI
S1A
201
202
203
A
B
U
4J18
8J18
7J18
2J23
4J22
1J22
2J22
3J22
6J22
AC
AC
115
115
INTERLOCK
INTERLOCK
V
V
TO HIGH FREQ
TO VALVE(S)
REMOTE
-
+
-
POT WIPER
*PuOT LO
DC
CURRENT
CONTROL
DC
DC
DC
N
10K
3J23
4J23
R
B
C
D
E
POLARITY
SWITCH
S1
24 VAC COMMON
ELECTRODE SENSE
REMOTE ARC START (TRIGGER) SWITCH 24 VAC
REMOTE CURRENT CONTROL HI
REMOTE CURRENT CONTROL WIPER
REMOTE CURRENT CONTROL LO
DC MODE SWITCH S1A 24 VAC
24 VAC OUT
7J23
8J23
5J23
B
1J16
2J16
3J16
5J16
6J16
7J16
8J16
REMOTE
1J9
2J9
B
50/ 100
R1
24 VAC OUT
REMOTE
ARC START
ELECTRODE SENSE
REMOTE ARC START 24 VAC
REMOTE POT HI
204
207
1J18
5J18
ARC START
SWITCH
CLOSED
IN DC
W
3J9
5J9
6J9
7J9
8J9
STOP
POWER START/
STOP PUSHBUTTON
REMOTE POT WIPER
REMOTE POT LO
DC MODE 24 VAC
F
NO CONNECTION
C1
START
CR1
PL1
OPTIONAL REMOTE AMPTROLTM
AND ARC START SWITCH
R2
25
S2
4/
220
SHUNT (+)
SHUNT (-)
1J8
2J8
222
221
25/
2J10
1J10
2J19
1J19
11J10
12J10
9J10
11J19
12J19
9J19
ELECTRODE
SENSE
INTERLOCK
INTERLOCK
CR1
INTERLOCK
8J17
3J17
2J17
225
241
242
8J10
8J19
241
242
7J10
7J19
6J10
6J19
5J10
5J19
4J10
4J19
SHUNT (+)
SHUNT (-)
SHUNT
222
221
3J10
3J19
400A/50mV
15J10
10J10
14J10
13J10
15J19
10J19
14J19
13J19
NOTE A: LEAD #250 FROM POWER FACTOR CAPACITORS CONNECTS AS
FOLLOWS, DEPENDING ON THE HIGHEST NAMEPLATE INPUT VOLTAGE:
L6
259
263
HIGHEST NAMEPLATE
INPUT VOLTAGE:
SHUNT TOROID
LEAD #250 CONNECTS TO "HIGH" TERMINAL ON
RECONNECT PANEL, ALONG WITH CORRECT LEAD
FROM MAIN TRANSFORMER (T1)
440 THRU 460
L2
L1
RF CHOKE
480 AND HIGHER
AND
LEAD #250 CONNECTS TO H5 LEAD OF
MAIN TRANSFORMER
RF CHOKE
CW
CW
CW
CW
CW
CW
CW
CW
CW
400 AND LOWER
C3
.0025/10KV
HIGH
VOLTAGE
TRANSFORMER
261
262
15/ 220
C6
SPOT
START
CRATER
START
TIME
PULSE
FREQ.
BACKGROUND
PREFLOW
PULSE
CRATER
FADE OUT
CW
TIME
%
PEAK
%
PEAK
CURRENT
TIME
%
ON
L4
L5
-DENOTES ACTIVE LOW LOGIC SIGNAL
115V HF
115V
CURRENT
CURRENT
*
R4
3/
228
232
4J17
CW-DENOTES CLOCKWISE POSITION WHEN VIEWED FROM FRONT OF POTENTIOMETERS.
ALL LOGIC IS 15V UNLESS OTHERWISE SPECIFIED.
25
R6
SPARK
GAP
100
150/
10J17
T4
HIGH FREQ.
TRANSFORMER
ELECTRICAL SYMBOLS PER E1537
T3
CW
CW
CW
CW
COMPONENT VALUES:
GAS
SOLENOID
WATER
SOLENOID
CAPACITORS
RESISTORS
DIODES AMPS/VOLTS
=
MFD/VOLTS
PEAK
AC
AFTER
FLOW
TIME
STICK
ARC
FORCE
SV1
SV2
CURRENT
WAVE
=
OHMS/WATTS
BALANCE
115V GAS
=
229
1J17
(
&
WATER
)
AUTO
BALANCE
LED
14J11
13J11
414
413
1J24
2J24
0.5
F1
A
A
WORK
ELECTRODE
LEAD COLOR CODING
CONTROL
115V
233
234
9J17
5J17
11J11
411
B=BLACK
N=BROWN
R=RED
U=BLUE
10J11
8J11
9J11
7J11
6J11
5J11
4J11
3J11
2J11
1J11
410
408
409
407
406
405
404
403
402
401
TRIAC 115V
W=WHITE
Y=YELLOW
F2
1.5
CHASSIS
CONNECTOR PIN NUMBERS:
EXAMPLE: THIS PIN IN
CONNECTOR J102
IS "6J102"
CONTINUOUS
1
2
1
2
3
8
ON
ON
4
2
STEP
STEP
LOCAL
START
OFF
ON
TIG
ON
VOLTS
AMPS
REMOTE
OFF
STICK
OFF
OFF
OFF
9
16
S10
S14
S18
S13
S12
S16
LATCH
S15
S11
S17
S19
12J11
412
X3
X4
CB1
REMOTE
PULSE
DISPLAY
METER
DISPLAY
HIGH
FREQ.
CRATER
FILL
SPOT
START
CURRENT
2
STEP/4 STEP
MODE
115V/15A
VIEW OF CONNECTOR ON PC BOARD
START CURRENT
FAN
FAN
115 VAC
RECEPTACLE
(+)15
V
C8
.22/400V
HIGH FREQ.
ARC ESTAB.
START
C7
.22/400V
5J12
6J12
305
306
307
308
309
310
311
312
305
306
307
308
309
310
311
312
8J601
7J601
6J601
5J601
1J601
2J601
4J601
3J601
4P602
4J701
5J701
EJ701
DJ701
1J701
6J701
CJ701
3J701
GAS
&
WATER
*
5P602
HIGH FREQ.
ARC ESTAB.
START
*
*
7J12
EP602
*
PEAK
*
(OPTIONAL)
8J12
9J12
10J12
11J12
12J12
DP602
1P602
6P602
*
BACKGROUND
*
PEAK
*
CRATER FILL
(+)15
*
BACKGROUND
*
V
*
CP602
CRATER FILL
*
3P602
*
TS701
5-14-93F
2522
EQUIP.
SQUARE WAVE TIG 355
MACHINE SCHEMATIC
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
TYPE
SUBJECT
SCALE
NONE
SHT.
NO.
G2113
JJJ
4-2-92
REF.
DR
DATE
CHK
SUP'S'D'G
G
NOTE: This diagram is for reference only. It may not be totally applicable to every code covered by this manual.
8/98
SQUARE WAVE TIG 355
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G-4
G-4
ELECTRICAL DIAGRAMS
Meter PC Board (M15893) Schematic
1 5 8 9 M 2
+5V
Q1
300mA
30V
D1
3
8
3
8
3
8
1
1
1
3.32K
2
4
5
6
7
9
2
4
5
6
7
9
2
4
5
6
7
9
C1
5
9
6
LED1
LED2
LED3
X5
X5
475
R1
10
10
10
D2
1N914
8
3
4
5
6
A
B
C
D
E
F
+5V
3
4
5
6
3
4
5
6
A
B
C
D
E
F
A
B
C
D
E
F
+5V
+5V
X3
X1
X2
+5V
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
1
A1
1
1
A1
A1
2
8
9
13
A2
J7
2
8
9
13
2
8
9
13
A2
A2
2
+5V IN
10
11
CLK
R
10
11
10
11
CLK
R
CLK
R
12
3.01K
3.01K
G
Q
H
12
12
G
Q
H
G
Q
H
74HC164
74HC164
74HC164
J7
J7
13
12
11
10
1
R25
X5
X5
DATA
+5V
+5V
1
2
3
4
3
R26
X5
X5
CLOCK
14
1
RESET
1
VCC
C5
330p
50V
C6
330p
50V
2
13
12
11
10
9
RESET 2
DATA
1
3
4
5
6
7
DATA 2
CLOCK 2
SET 2
CLOCK
1
J7
4
SET
Q1
1
COMMON
+5V
/Q1
Q2
X4
54HC74
8
GND
N.C.
14
14
14
14
14
GENERAL INFORMATION
LAST NO. USED
R- 28
X1
X2
X3
X5
C7
C8
X4
C2
C3
C4
74HC164
74HC164
74HC164
54HC74
HEXINV
ELECTRICAL SYMBOLS PER E1537
C-
D-
8
2
CAPACITORS
RESISTORS
DIODES
=
MFD
(
.022/50V
1/4W
UNLESS OTHERWISE SPECIFIED)
UNLESS OTHERWISE SPECIFIED)
LABELS
=
Ohms
(
7
7
7
7
7
=
1A, 400V
(UNLESS OTHERWISE SPECIFIED)
SUPPLY
VOLTAGE NET
POWER SUPPLY SOURCE POINT
COMMON CONNECTION
NOTES :
NOTE: ALL UNMARKED RESISTORS = 100 OHMS
N.A. SINCE COMPONENTS OR CIRCUITRY ON
A
PRINTED CIRCUIT BOARD MAY CHANGE
COMPLETE BOARD, THIS DIAGRAM MAY
FRAME CONNECTION
WITHOUT AFFECTING THE INTERCHANGEABILITY OF
A
NOT SHOW THE EXACT COMPONENTS OR CIRCUITRY OF CONTROLS HAVING A COMMON CODE
NUMBER.
EARTH GROUND CONNECTION
UNLESS OTHERWISE SPECIFIED TOLERANCE
ON HOLES SIZES PER E-2056
Ch'ge.Sht.No.
EQUIP.
TYPE
CV WELDERS
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
2-16-90
ON
ON
2
3
PLACE DECIMALS IS
PLACE DECIMALS IS
+
+
.O2
.OO2
4-30-93A
METER P.C. BOARD SCHEMATIC
SUBJECT
ON ALL ANGLES IS
+
.5 OF
A
DEGREE
NONE
SCALE
MATERIAL TOLERANCE ("t") TO AGREE
WITH PUBLISHED STANDARDS
SHT.
JCP
01-06-89
CHK.
SUP'S'D'G.
M15892
DR.
DATE
NO.
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-5
G-5
ELECTRICAL DIAGRAMS
Feed Through PC Board (L8096) Schematic
1 6 0 M 7 0
L1
L11
J15
5
J17
J17
J16
1
7
.39mH
.39mH
C3
C11
C1
J18
.0047
3000V
.0047
.0047
3000V
1
3000V
L2
L12
J15
J16
J16
4
6
2
.39mH
.39mH
C2
C19
C12
.0047
3000V
.0047
3000V
J17
J18
.0047
8
3000V
L13
3
.39mH
C13
C21
.0047
.0047
5
3000V
3000V
L4
J15
J15
J17
J17
6
7
10
.39mH
1A
C20
.0047
C4
3000V
.0047
3000V
L5
9
L15
.39mH
1A
J16
J16
J16
5
6
7
.39mH
C5
.0047
3000V
C15
L6
J18
J18
J18
.0047
3000V
J15
J15
J17
J17
4
8
7
10
4
L16
.39mH
1A
.39mH
C6
.0047
3000V
L7
C16
.0047
3000V
2
1
L17
.39mH
1A
.39mH
C7
.0047
3000V
C17
L8
.0047
3000V
J15
J15
J17
J17
8
9
2
3
.39mH
1A
L18
J16
8
C8
.39mH
.0047
3000V
L9
C18
C22
J18
.0047
3000V
.0047
6
.39mH
1A
3000V
chassis
C9
.0047
3000V
GENERAL INFORMATION
ELECTRICAL SYMBOLS PER E1537
LAST NO. USED
L10
R-
C-
D-
_
_
_
J15
J17
NOTES :
1
5
CAPACITORS
RESISTORS
DIODES
=
MFD ( .022/50V
UNLESS OTHERWISE SPECIFIED)
.39mH
1A
LABELS
=
Ohms
1A, 400V
(
1/4W UNLESS OTHERWISE SPECIFIED)
(UNLESS OTHERWISE SPECIFIED)
N.A. SINCE COMPONENTS OR CIRCUITRY ON
A
PRINTED CIRCUIT BOARD MAY CHANGE
COMPLETE BOARD, THIS DIAGRAM MAY
=
WITHOUT AFFECTING THE INTERCHANGEABILITY OF
NOT SHOW THE EXACT COMPONENTS OR CIRCUITRY OF CONTROLS HAVING
NUMBER.
A
SUPPLY
VOLTAGE NET
C10
A
COMMON CODE
.0047
POWER SUPPLY SOURCE POINT
COMMON CONNECTION
3000V
chassis
FRAME CONNECTION
EARTH GROUND CONNECTION
UNLESS OTHERWISE SPECIFIED TOLERANCE
THIS SHEET CONTAINS PROPRIETARY INFORMATION
EQUIP.
ON HOLE SIZES PER E2056
SQUARE WAVE TIG 350
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
TYPE
OWNED BY
AND IS
5-29-90SPA
THE LINCOLN ELECTRIC CO.
ON 2 PLACE DECIMALS IS .02
ON 3 PLACE DECIMALS IS .002
ON ALL ANGLES IS .5 OF A DEGREE
MATERIAL TOLERANCE (" ") TO AGREE
WITH PUBLISHED STANDARDS.
NOT TO BE REPRODUCED, DISCLOSED OR USED
WITHOUT THE EXPRESS PERMISSION OF
FEEDTHRU P.C. BD. SCHEMATIC
SUBJECT
NONE
1-12-90
SCALE
SHT.
NO.
t
THE LINCOLN ELECTRIC CO.
MK/DRS
GM/BS
REF.
16070
DR
M
DATE
CHK
SUP'S'D'G
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-6
G-6
ELECTRICAL DIAGRAMS
Protection PC Board (M16062) Schematic
1 6 1 M 1 5
L4
J23
J22
J22
J22
J22
J22
J22
1
2
3
4
5
5
4
1
2
6
3
.39mH
C4
.0047
3000V
L5
J23
J23
J23
J23
.39mH
C5
.0047
3000V
L1
.39mH
C1
.0047
3000V
L2
.39mH
C2
.0047
3000V
L6
.39mH
C6
.0047
3000V
L3
J23
J23
7
.39mH
C3
.0047
3000V
8
GENERAL INFORMATION
LAST NO. USED
R-
C-
D-
_
_
_
ELECTRICAL SYMBOLS PER E1537
CAPACITORS =
MFD ( .022/50V
UNLESS OTHERWISE SPECIFIED)
LABELS
RESISTORS = Ohms (
1/4W UNLESS OTHERWISE SPECIFIED)
(UNLESS OTHERWISE SPECIFIED)
DIODES =
1A, 400V
SUPPLY
VOLTAGE NET
POWER SUPPLY SOURCE POINT
COMMON CONNECTION
NOTES :
N.A. SINCE COMPONENTS OR CIRCUITRY ON A PRINTED CIRCUIT BOARD MAY CHANGE
WITHOUT AFFECTING THE INTERCHANGEABILITY OF A COMPLETE BOARD, THIS DIAGRAM MAY
NOT SHOW THE EXACT COMPONENTS OR CIRCUITRY OF CONTROLS HAVING A COMMON CODE
NUMBER.
FRAME CONNECTION
EARTH GROUND CONNECTION
UNLESS OTHERWISE SPECIFIED TOLERANCE
ON HOLE SIZES PER E2056
ON 2 PLACE DECIMALS IS .02
THIS SHEET CONTAINS PROPRIETARY INFORMATION
EQUIP.
SQARE WAVE TIG 350
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
TYPE
OWNED BY
AND IS
5-29-90SPA
THE LINCOLN ELECTRIC CO.
NOT TO BE REPRODUCED, DISCLOSED OR USED
WITHOUT THE EXPRESS PERMISSION OF
ON 3 PLACE DECIMALS IS .002
ON ALL ANGLES IS .5 OF A DEGREE
PROTECTION P.C. BOARD SCHEMATIC
SUBJECT
NONE
1-12-90
SCALE
SHT.
t
MATERIAL TOLERANCE (" ") TO AGREE
THE LINCOLN ELECTRIC CO.
MK/DRS
GM/BS
REF.
16115
DR
M
DATE
CHK
SUP'S'D'G
NO.
WITH PUBLISHED STANDARDS.
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-7
G-7
ELECTRICAL DIAGRAMS
Power PC Board (G2081) Schematic
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-8
G-8
ELECTRICAL DIAGRAMS
OCV BOOST
J14
J14
DC RELAY
AC RELAY
*
*
6
7
R66
3.01K
Control PC Board
(G2512) Schematic
R67
3
4
9
X32
Q9
600mA
40V
8
3.01K
R73
X3
10
680
1W
4.75K
+5V
J13
J13
GAS ON
*
8
9
R8
R11
3.01K
Q2
600mA
40V
J9
R9
ARC START
+5V
STICK
AC MODE
3
12
13
R12
SWITCH INTERFACE
Q1
600mA
40V
10K
11
3.01K
680
1W
4.75K
R7
X3
1.50K
D20
D22
475
4.75K
HI FREQ ON
*
VREF
D32
R13
ARC START
*
D62
20
10K
19
18
17
16
X2
Vcc
POT INTERFACE
Q3
600mA
40V
4
3
X1
X
10K
R14
X17
J11
J11
1
5
STICK
3
R101
100
X0
NC
NC
LTEN
EN1
EN2
A
4.75K
C46
1.00K
+5V
24 VAC Input
OCI1
CNY17-3
J10
14
11
7
PEAK CURRENT
X3
13
R81
100
D63
+5V
1
X4
BIT I/O
VREF
D37
C51
18
ANALOG
MUX
2
6
4
D33
6
2
5
9
X5
D58
10K
15V
8
X6
D21
D24
D87
LED/DISPLAY INTERFACE
C73
150p
50V
475
475
15
13
12
DATA[0]
DATA[1]
DATA[2]
X7
20
J10
3
4
7
8
DATA[0]
DATA[1]
DATA[2]
DATA[3]
DATA[4]
DATA[5]
DATA[6]
DATA[7]
REMOTE
AC BALANCE
1D
Vcc
1Q
1
10
R97
R84
100
681K
Vee
GND
B
16
VREF
2
13
2D
3D
4D
5D
6D
7D
8D
G
X42
DTIN
Vcc
Q0
Q1
100
10
J9
SWITCH COMMON
D39
C
J12
J12
J12
J12
J12
J12
J12
1
5
1
4
1
16
15
14
13
12
11
D59
2Q
A0
I0
O0
O1
GASWAT
HI FREQ
*
*
6
54HC4351
+5V
D40
X25
6
2
3
5
2
3
4
5
6
7
8
3Q
A1
X13
I1
*
*
7
+5V
13
9
6
4Q
A2
Q2
Q3
I2
O2
ARC
*
8
D23
J10
J10
1.50K
D70
AFTERFLOW
PREFLOW
1
OF
8
10K
15
3
14
17
18
11
12
15
16
19
1
14
7
R85
I3
O3
START
PEAK
*
10K
5Q
EN
9
VREF
DECODE
100
15
9
D41
6Q
RST
Q7
Q4
Q5
Q6
I4
O4
*
J11
J11
D79
5
10
11
12
HF OFF
LED
DRIVER
7
R109
100
10K
12
8
10
11
AC MODE
D42
7Q
I5
O5
BACKGND
CRATER
+5V
6
BIT I/O
SET
54HC373
3
4
2
/K
Q
10
1.00K
24 VAC Input
D71
8Q
GND
I6
O6
R86
CLK
J
10
54HC259
1
5
9
X19
GND
O
CTRL
GND
CLAMP
VREF
D34
7
100
D74
/Q
MC1413BP
10K
10K
10K
C62
OCI4
CNY17-3
D44
4.75K
RST
1
+15V
TP1
3
HF CONTINUOUS
OP3 B7
Q11
2
6
4
9
7
R113
100
C72
18
D88
D89
AC MODE
20
J10
J10
J12
7
4
3
8
3D
Vcc
1Q
STICK FORCE
SPOT TIME
LED POWER
+5V
D66
14
5
R82
100
475
DATA[3]
VREF
D45
2
DATA[0]
DATA[1]
DATA[2]
DATA[3]
DATA[4]
DATA[5]
DATA[6]
DATA[7]
15V
C25
0.1
50V
C68
4.7
35V
2D
1D
X11
-15V
X38
2
R162
1.00K
D75
14
1
RESET
1
VCC
D36
5
HARD_RST
C74
150p
50V
2Q
J9
J11
J11
2
3
4
5
6
7
13
12
11
10
9
DATA
1
RESET
DATA
2
DC MODE
681K
20
10K
8
6
9
14
13
HARD_RST
R161
600mA
40V
4D
5D
6D
7D
8D
G
3Q
Vee
X0
Vcc
X
1
2
CLOCK
1
13
9
17
4
3
4.75K
LATCH
4Q
4
R88
100
AUTO BALANCE
LED
X18
LED SET
*
SET
Q1
1
CLOCK
2
J11
J11
14
17
18
11
12
15
16
19
1
18
19
16
CLKOUT
+5V
SHOW VOLTS
5Q
X1
NC
NC
LTEN
EN1
EN2
A
VREF
D48
5
R105
100
SET
2
D47
+5V
14
6Q
X2
X39
HARD_RST
/Q1
NC
Q2
11
D67
+5V
7Q
X3
54HC373
8
GND
N.C.
J10
J10
1
7
8
8Q
START CURRENT
START TIME
X4
ANALOG
MUX
+5V
5
6
R89
100
54HC74
AMPTROL INTERFACE
D60
D61
10
6
2
5
GND
O
CTRL
X5
VREF
D50
J12
J12
D49
1
DIPLAY VCC
15
13
12
DATA[0]
DATA[1]
DATA[2]
C65
27
10V
X6
SPOT
2
R99
100
X7
B
DISPLAY GND
2
R126
10
R92
GND
C
4.75K
54HC4351
VREF
D52
100
+15V
A=2.43
3.32K
D51
10K
14
J12
J12
1
100
100
RESET
1
VCC
+5V
DISPLAY DATA
DISPLAY CLK
3
4
HARD_RST
R119
D64
D65
+15V
2
3
4
5
6
7
13
12
11
10
9
DATA
1
RESET
DATA
2
C56
HARD_RST
.1
16
J10
J10
2
13
1
R120
CLOCK
1
PULSE FREQUENCY
BACKGROUND
DTIN
A0
Vcc
Q0
J11
J11
7
8
Q10
600mA
40V
R93
50V
SHOW START CUR
OP2 B8
VREF
4
R103
100
BITS OUT
*
TP1
4
SET
Q1
1
CLOCK
2
+5V
VREF
100
8
CLKOUT
+5V
D85
D86
D53
2
6
SET
2
A1
X14
Q2
Q3
Q1
X41
3
7
/Q1
D54
D55
NC
Q2
A2
1
OF
8
PTC1
13
12
D68
D69
J9
8
14
15
5
GND
N.C.
REMOTE HI
Vout=10.2V
EN
DECODE
J13
5
X29
R125
267
R124
R123
10K
OVER_VOLT
14
5
6
10
R94
100
R32
54HC74
POWERDOWN
(To Opto-triac
Interlock Circuit)
11
10
9
X32
+
t
D84
RST
Q7
Q6
Q5
Q4
(Voltage FB)
47.5K
20
VREF
D56
11
1W
Q4
600mA
40V
680
56
START CUR
G
Vcc
1Q
6
12
8
R107
100
D13
CUR_GAIN
ARC START
*
+5V
D72
D73
13
2
1
2
DATA[8]
DATA[9]
5D
1D
X12
X32
R33
4.75K
C52
4.75K
(X30 Current FB)
GND
3
5
.02
2Q
54HC259
600V
10K
J10
J10
J10
4
7
8
6
DATA[10]
DATA[11]
DATA[12]
DATA[13]
DATA[14]
DATA[15]
2D
3D
4D
6D
7D
8D
GND
3Q
PULSE
%
10K
9
R95
100
VREF
9
LATCH
4Q
VREF
D35
D57
12
15
16
19
1
+15V
5Q
J11
PULSE
8
14
R111
100
6Q
+5V
D25
17
18
7Q
CRATER FADE
12
11
5
R83
100
54HC373
R75
10K
D26
D28
VREF
D43
8Q
J9
J9
J14
C61
10
7
REMOTE TAP
REMOTE LOW
BACKGND CMD
6
7
4
5
R63
R60
4.75K
X26
R76
1K
10
D38
A/D INTERFACE
1
5
REM CUR
D76
D77
O
CTRL
8
6
1.00M
SCR/BACKGND CNTRL
4.75K
X26
R61
332
10K
OCI3
CNY17-3
9
100
D27
J11
J11
C53
.02
600V
CRATER
CRATER CURRENT
10
12
R115
100
R87
R78
47.5K
TP1
243
IP2 B15
IP2 B14
3
2
2
6
4
J14
D46
D31
BACKGND GND
+15V
-15V
VREF
10K
PTC2
TP1
SWITCH GND
R118
681K
R90
100
+
t
+5V
100
56
Offset
Adjust
J10
J10
3.01K
D92
3.01K
D93
16
1
1
R74
POT REF
POT GND
CLK Aa
RSTa
QAa
Vcc
R151
475
CLKOUT*
+15V
267
100
2
3
4
5
6
7
15
14
13
12
11
CLK Ab
RSTb
QAb
D96
R134
100
R154
X2
10K
VREF
+5V
CW
1K
J11
2
R135
100
CLK Ba
QBa
11
R160
100
2/4 STEP
20
20
+15V
12
11
3
REF+
AG IN
REF-
/OFLW
NC
Vcc
G
Vcc
1Q
CLK Bb
QBb
1
2
3
4
5
2
DATA[0]
DATA[1]
DATA[2]
DATA[3]
DATA[4]
DATA[5]
DATA[6]
DATA[7]
2700p
D97
Gain
D0
D1
1D
X40
RIPPLE
COUNTER
TP1
QCa
100K
C1
0.1
CURRENT TEST
X16
CLN
50V
10
11
4
7
5
1
R149
10K
2D
3D
4D
5D
6D
7D
8D
GND
2Q
10
Q5
600mA
40V
C50
QDa
GND
QCb
3
18
19
6
R65
50V
D2
D3
D4
D5
D6
D7
3Q
8
51.2 KHZ 20%
X3
J14
9
2
QDb
SCR CLN
*
+5V
2
R35
R38
R146
1.00K
+5V
8
9
1.50K
C54
2700p
50V
4Q
54HC390
LATCH
51.1K
4.75K
R31
10K
9.09K
R36
10K
Q6
8A
150V
D14
D15
+15V
11
12
13
14
3
2
9
1
7
14
13
14
17
18
12
15
16
19
1
16.2K
CLK1
MODE
/WR
5Q
CLKOUT
Current
Calibration
R37
+15V
CW
A/D
6
15
16
17
X15
Q
H
6Q
Rectifier
Balance
Adjust
C55
J8
13
CURRENT FB+
To Shunt
D16
SS/PL
/CS
7Q
10K
1
R34
500
54HC373
267
2
7
8
DC
BA
Q
H
/RD
8Q
10K
1.00K
R39
10K
1K
CW
CW
R129
10
10
J14
J14
1
6
15
10
6
9
E
F
CLK2
SA
GND
/INT
O
CTRL
3
1
R128
X29
R41
SHIFT
REGISTER
SCR GND
SCR PEN
C69
0.1
50V
TLC0820AI
3
7
4
D17
PEN
100
4.75K
5
4
1.50K
X29
5
1
8
Q7
600mA
40V
NULL
INPUT
INPUT
NULL
5
6
G
H
R43
R70
7
X3
*
2
3
V
CC
74HC165
-15V
DATA[0:15]
4.75K
Q8
X27
J8
6
5
C57
2700p
50V
CURRENT FB-
OUT
NC
2
R40
1K
8A
4.75K
4
150V
V
EE
OP27
C58
+5V
10K
VREF
FB CURRENT->
"Select Channel and Convert"
11
D94
10
10
9
14
SET
/K
8
1
4
13
XA
XB
XC
XD
Vcc
Q
X28
R157
X30
"25us Timeout" ->
9
2
3
12
14
CURRENT/VOLTAGE FEEDBACK
YA
YB
YC
YD
CLK
1.00K
D95
X19
/Q
"Missed Watchdog Reset*"
16
8
1
<-
A/D EOC*
Q12
Q6
Q5
Q7
Q4
Q3
Q2
V
CC
Q11
Q10
Q8
Q9
R
J
ANALOG
SWITCH
RST
11
6
9
2
3
4
5
6
7
15
14
NC
X10
R48
+5V
10
15
Cctrl
Actrl
GND
NC
J9
+15V
150K
VOLTAGE FB
(Electrode
Terminal)
2
10K
<-FULL RANGE CURRENT
TIMER
13
D_TIMER*
6
TP1
13
7
5
5
Bctrl
Dctrl
5
X34
6
Logic
0
/
A=16
BITS IN*
16
6
1
Y2a
VCC
Y0a
Y1a
FAULT DETECT
12
12
11
10
9
1
/
A=1
22.1K
"DATA ENABLE" ->
*
TP1
9
RIPPLE
COUNTER
10K
TP1
4
54HC4066
X32
select
A0a
a
IP0_STB*
4
VREF
D18
X20
A/D READ* ->
2
3
5
7
D9
20
X35
C
WATCHDOG
DISABLE
3
5
ADDRESS[0]
ADDRESS[1]
ADDRESS[2]
1D
Vcc
1Q
6
FB Voltage
Calibration
A1a
Y3a
Y0b
DATA_RD1
NC
8
*
10
9
10
11
1
Q1
GND
X20
4
7
8
2
HARD_RST
X32
2D
3D
4D
5D
6D
7D
8D
G
X36
15
12
11
CW
select
b
74HC4040
8
3
CUR_GAIN
(X14 pin12)
HARD_RST
12
12
13
5
2
X29
R158
C71
.02
2Q
3Q
4Q
5Q
6Q
7Q
8Q
14
13
A0b
A1b
Y1b
Y2b
Y3b
14
1.00K
6
500
D19
10
X31
600V
NC
NC
13
13
9
CLKOUT
8
9
D11
GND
14
17
18
11
12
15
16
19
1
5
2
1
VREF
NC
74AC139
X37
3
C48
"WRITE ENABLE" ->
*
X23
6
7
1.50K
NC
LWE*
SET
3
/K
Q
15
4
2
CLK
J
16
1
A
Vcc
/Y5
/Y1
X24
10
9
74AC373
NC
RST
/K
-15V
13
12
14
CLKOUT*
D5
/Q
Q
2
3
4
5
6
7
10
14
13
12
15
11
10
B
IOWR1*
A/D SET
GND
O
CTRL
RST
1
6
*
CLK
C
X24
/Q
"Multiple Watchdog Resets"
FB VOLTS
10
9
7
BITS OUT
LED SET
*
J
R16
10K
X28
R142
267
/G2A
/G2B
G1
/Y2
HARD_RST
INT
SET
8
5
*
"Interrupt uP" X4pin5
1R01K5
X31
R17
4.75K
/Y3
11
4.75K
D8
SOFT WATCH
SOFT ERR*
*
"Watchdog Reset ->"
+5V
/YO
CLKOUT
6
5
C47
"Software Error Detected"->
12
R19
10K
R20
10K
IOWR3*
/Y7
GND
/Y4
/Y6
7
11
8
9
X31
IOWR2*
X20
13
HARD_RST
MAIN PROCESSOR
74AC138
+5V
D6
+5V
2
3
11
2
9
1
CLK1
10
R23
10K
ADDRESS[0:11]
VREF
1
12
13
14
4
5
8
4.75K
X22
Q
H
D7
X31
R24
10K
X23
6
9
X23
+5V
D10
51.1K
SS/PL
7
DC
BA
Q
H
3
15
28
E
F
CLK2
SA
2
1
26
1
ADDRESS[0]
ADDRESS[1]
ADDRESS[2]
ADDRESS[3]
ADDRESS[4]
ADDRESS[5]
ADDRESS[6]
ADDRESS[7]
ADDRESS[8]
DATA[0]
DATA[1]
DATA[2]
DATA[3]
DATA[4]
DATA[5]
DATA[6]
DATA[7]
DATA[8]
DATA[9]
4.75K
D12
A0
D0
Vpp
Vcc
A0
A1
30.1K
4
5
10
2
3
25
D1
11
10
9
DATA[0]
DATA[1]
DATA[2]
DATA[3]
DATA[4]
DATA[5]
DATA[6]
DATA[7]
ADDRESS[0]
ADDRESS[1]
ADDRESS[2]
ADDRESS[3]
ADDRESS[4]
ADDRESS[5]
ADDRESS[6]
ADDRESS[7]
ADDRESS[8]
ADDRESS[9]
ADDRESS[10]
ADDRESS[11]
A1
D0
6
G
H
1
40
24
12
13
15
16
17
18
19
26
27
22
A2
D2
D1
X28
R130
10K
X5
74HC165
CLKOUT*
X4
39
38
37
36
35
23
22
21
20
19
11
8
A3
D3
D4
D2
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
D91
7
A4
D3
6
11
2
9
HARD_RST
(X20 pins 2,5,10,13;
X13,14,24,4,39,41)
A5
D5
D4
CLK1
OVER_VOLT
68.1K
C49
18
5
12
13
14
R29
10K
A6
D6
D5
X21
Q
H
(Powerdown Circuit)
13
12
D78
4
1
15V
A7
D7
D6
SS/PL
11
X23
34
10
3
7
A8
D8
D7
EPROM
DC
Q
H
+5V
B
+5V
12
25
24
21
23
2
3
15
10
6
Vss
A9
D9
NC
/PGM
/DE
/CE
GND
E
CLK2
30
29
28
27
31
4
5
ADDRESS[9]
ADDRESS[10]
ADDRESS[11]
Vcc
D10
D11
F
10K
13
14
15
16
17
18
7
DATA[10]
DATA[11]
DATA[12]
DATA[13]
DATA[14]
DATA[15]
A10
A11
/WE
/DEN
/BIO
/INT
/RS
/MEN
MC
G
HSA
uP
74HC165
20
14
TESTCODE
*
D12
D13
D14
D15
X1
4
27C64-90
TP1
32
+15V
+5V
A/D EOC* ->
X24pin7 (Fault Detect)
+5V
9
C59
28
Reset Error Counter
9
16
5
4
1
11
1
Vpp
D0
Vcc
A0
A1
Q12
Q6
Q5
Q7
Q4
Q3
Q2
V
CC
INT
HARD_RST
X32
POWER SUPPLY
10
9
8
2
3
4
5
6
7
15
14
13
12
11
DATA[8]
DATA[9]
DATA[10]
DATA[11]
DATA[12]
DATA[13]
DATA[14]
DATA[15]
ADDRESS[0]
ADDRESS[1]
ADDRESS[2]
ADDRESS[3]
ADDRESS[4]
ADDRESS[5]
ADDRESS[6]
ADDRESS[7]
ADDRESS[8]
ADDRESS[9]
ADDRESS[10]
ADDRESS[11]
D3
D4
X7
Q11
Q10
Q8
Q9
R
10K
2
33
8
12
13
15
16
17
18
19
26
27
22
X2
D1
X6
RESET FREQUENCY
J13
12
13
3
6
8
CLKOUT
19.6608MHz
40
D2
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
6
R5
10K
AC SYNC->
Y1
TMS320C10A
60Hz 34 sec
50Hz 41 sec
14
7
D3
X26
R6
1
6
D83
D82
D4
10K
CLKOUT
CLKOUT*
(X10,15,37)
(X2,21,36)
5
10
D5
C
4
C64
C63
10p
100V
8
4
9
6
10p
D6
Q1
NC
GND
X38
X38
X38
5
100V
74HC4040
-15V
3
D7
EPROM
9
X34
2
1
25
24
21
23
2
NC
/PGM
/DE
/CE
GND
8
DATA[0:15]
9
X20
10
8
HARD_RST
NC
10
13
12
20
14
14
ADDRESS[0:11]
NC
+5V
12
13
X28
11
27C64-90
NC
J13
+UNREG
1
"MEMORY ENABLE"
+5V
TRIP POINT
+8.4V
D1
VREF
AC SYNC
"50 or 60 Hz"->
X1
10K
1
3
+8.8V
IN
OUT
7805
S18104-2HS
D2
2
3
4.75K
3
9
4
NC
X34
C42
.33
50V
C43
150
50V
C44
4.7
35V
C132
POWERFAIL* ->
"Voltage below trip point"->
1
GND
D29
2
X26
R3
D80
10K
8
NC
J13
J13
X34
X34
X34
-UNREG
P_GND
2
5
C45
.33
50V
D81
+5V
R141
4.75K
D90
100K
11
10
NC
16
14
30
28
28
16
16
20
20
16
16
16
20
20
20
16
C100
0.1
50V
C101
C108
0.1
50V
C127
0.1
50V
C128
C122
0.1
50V
C111
C104
0.1
50V
C110
0.1
50V
C102
C103
0.1
50V
C130
C114
C67
C115
0.1
50V
C116
0.1
50V
C113
0.1
50V
X2
X4
X5
X6
X7
X10
X11
X12
X13
X14
0.1
X15
X16
X17
X18
X19
X3
0.1
0.1
0.1
0.1
0.1
4.7
13
12
50V
50V
50V
50V
50V
50V
35V
54HC08
NC
TLC0820AI
10
54HC390
5320C10A
10
27C64-90
27C64-90
74HC4040
8
74HC4040
8
74HC373
74HC373
10
54HC259
8
54HC259
74HC165
8
54HC4351
10
54HC4351
10
54HC109
VREF
8
7
14
14
10
8
8
4.20V
-15V
+15V
J13
J13
J13
VREF
+15V
-15V
7
3
4
+5V
A475-1BB
GENERAL INFORMATION
ELECTRICAL SYMBOLS PER E1537
LAST NO. USED
14
16
16
14
16
14
14
14
16
20
16
14
14
20
14
20
162
R-
C-
D-
_
_
_
4
7
4
4
4
C38
C26
0.1
C27
C28
C29
0.1
C31
C107
X39
X41
MFD
132
97
CAPACITORS
RESISTORS
DIODES
=
(
.022/50V
1/4W
UNLESS OTHERWISE SPECIFIED)
UNLESS OTHERWISE SPECIFIED)
150
5C03V7
4.7
0.1
0.1
0.1
C117
0.1
50V
C123
0.1
50V
C121
C120
C119
0.1
50V
C131
0.1
50V
C112
0.1
50V
C109
0.1
50V
C124
C118
C106
0.1
50V
C129
0.1
50V
C105
0.1
50V
681
681
X35
C125
0.1
50V
0.1
C126
0.1
50V
X21
X22
X24
X30
X36
X37
X40
X42
X20
X23
X32
X34
X38
LABELS
SUPPLY
=
Ohms
(
35V
50V
50V
50V
50V
50V
0.1
0.1
0.1
0.1
50V
50V
50V
50V
50V
=
1A, 400V
(UNLESS OTHERWISE SPECIFIED)
54HC00
54HC08
74HC04
74AC04
NAND
X26
X28
X29
X31
X27
VOLTAGE NET
74HC165
74HC165
54HC109
54HC4066
74AC373
74AC138
54HC74
7
74HC373
54HC74
7
74HC373
74AC139
8
R57
POWER SUPPLY SOURCE POINT
COMMON CONNECTION
LM224
11
OP27
33074A
11
33074A
33074A
C36
0.1
50V
1.82K
7
8
8
7
8
7
7
7
10
8
7
10
10
C32
0.1
50V
C33
0.1
50V
C34
0.1
50V
C35
0.1
50V
2.43K
+
1
4
11
11
C39
150
50V
C40
4.7
35V
FRAME CONNECTION
X33
8
C66
4.7
EARTH GROUND CONNECTION
REF
Reference
Voltage
Adjust
TL431
-
6
35V
EQUIP.
TYPE
Ch'ge.Sht.No.
N.A. SINCE COMPONENTS OR CIRCUITRY ON
A
PRINTED CIRCUIT BOARD MAY CHANGE
COMPLETE BOARD, THIS DIAGRAM MAY
SQUARE WAVE 355
UNLESS OTHERWISE SPECIFIED TOLERANCE
ON HOLES SIZES PER E-2056
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
WITHOUT AFFECTING THE INTERCHANGEABILITY OF
A
CW
500
5-8-92E
6-11-93H
NOT SHOW THE EXACT COMPONENTS OR CIRCUITRY OF CONTROLS HAVING
NUMBER.
A
COMMON CODE
ON
ON
2
3
PLACE DECIMALS IS
PLACE DECIMALS IS
+
+
.O2
.OO2
CONTROL
SCHEMATIC
SUBJECT
NONE
SCALE
DATE
ON ALL ANGLES IS
+
.5 OF
A
DEGREE
SHT.
NO.
DB/MW
9/24/90
MATERIAL TOLERANCE ("t") TO AGREE
WITH PUBLISHED STANDARDS
A
CHK.
SUP'S'D'G.
475
DR.
AUSTRALIA
CANADA
FRANCE
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-9
G-9
ELECTRICAL DIAGRAMS
Protection PC Board (M16062) Layout
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-10
G-10
ELECTRICAL DIAGRAMS
Power PC Board (G2081) Layout
ITEM
REQ'D.
IDENTIFICATION
C1
1
2
2
3
2
1
3
2
150/50
.022/50
.047/100
.1/400
2.7/50
.47/50
C2,C9
C3,C16
C4, C5, C7
C6, C10
C8
C11, C13, C14
C12, C15
G2081
3300/50
1000/35
G2081
D11 thru D17,
D1 thru D7,
D20,D22,D23
1N4004
IN4936
17
4
1
1
1
1
1
1
4
3
2
1
5
D8,D9,D10,D21
J1
J2
J3
J4
J5
J6
LED1, LED2, LED3, LED4
OCI1, OCI2, OCI3
OCI4, OCI5
Q1
R1, R2, R6, R12, R24
R3
HEADER
HEADER
HEADER
HEADER
HEADER
HEADER
RED LED
3043
CS5010
TRANS-P T220 3 A, 100V, TIP32C
15K 1/4W
1.0 5W
1
R4, R9, R10
R5, R8, R14, R20
R7, R13, R25
3
200 1/4W
15 1W
27 1/2W
10 1/4W
SQUARE
WAVE
POWER
4
3
R11, R15
2
2
1
1
1
2
1
1
2.21K 1/4W
47.5K
R16, R30
R17
R18
3.01K 1/4W
68.1K 1/4W
2.7 1W
4.75K 1/4W
150 1/4W
R19
R21, R31
R27
R33
2
R34,R35
SCR1
2
1
1/
5W
2N6508
T1, T2
2
1:1:1
3
T2500D
TRI1, TRI2, TRI3
X1
CAPACITORS = MFD/VOLTS
RESISTORS = OHMS/ 1/4 WATT UNLESS OTHERWISE SPECIFIED.
INDUCTANCE = HENRYS
VOLT-REG, FIXED 3-T (+), 1A,15V
1
1
1
1
X2
X3
VOLT-REG, FIXED 3-T (-), 1A,15V
OVER VOLTAGE SENSING 3523
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-11
G-11
ELECTRICAL DIAGRAMS
Bypass PC Board (M15299) Layout
IDENTIFICATION
ITEM
REQD
T4
WORK
BYPASS
M15299
CAPACITORS = MFD/VOLTS
M15299
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-12
G-12
ELECTRICAL DIAGRAMS
Feed Through PC Board (L9096) Layout
REQ'D
21
ITEM
IDENTIFICATION
C1,C2,C3,C4,C5,C6,C7,C8,C9,C10,
C11,C12,C13,C15,C16,C17,C18,C19,
.0047/3000 V
C20,C21
,C22
L1,L2,L11,L12,L13,L15,L16,L17,
L18
0.39mH, 225mA
0.39mH, 1A
9
7
L4,L5,L6,L7,L8,L9,L10
CAPACITORS = MFD/VOLTS
INDUCTANCE = HENRYS
L8096
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-13
G-13
ELECTRICAL DIAGRAMS
Control PC Board (G2512) Layout
ITEM
REQ'D.
IDENTIFICATION
C1,C25-C29,C31-C36,C56,C69,C100-C131
C37,C39,C43
C38,C40,C44,C66,C67,C68
C42,C45
46
3
6
0.1
150
4.7
.33
/
/
/
/
50
50
35
50
G2512
2
C46,C47,C48,C55,C58,C59,C61,C62,C132
9
3
3
3
2
1
2
.022
18
2700pf
.02 600
10pf 100
27 10
150pf
/
15
50
/
C49,C51,C72
C50,C54,C57
/
50
C52,C53,C71
C63,C64
C65
/
/
/
C73,C74
/
100
D1 thru D29,
D31 thru D97
96
3
1N4004
OCI1,OCI3,OCI4
Q1 thru Q5,Q7,Q9,Q10,Q11
Q6,Q8
9
2
56, 20%
PTC1,PTC2
2
R1,R4,R7,R12,R14,R17,R18,R21,
R28,R31,R33,R41,R42,R43,R60,
R63,R73,R126,R127,R131,R161
R2,R3,R5,R6,R10,R15,R16,R19,
R20,R23,R24,R29,R35,R36,R39,
R51,R53,R68,R71,R72,R75,R80,
R96,R98,R100,R102,R104,R106,R108,
R110,R112,R114,R116,R121,R122,R123,
R130,R133,R149,R156,R159
21
4.75
K
1/4W
10K 1/4
W
41
R8,R9,R66,R67,R152,R153
3.01
K
1/4W
6
3
R11,R13,R32
680 1W
1.5
22.1
30.1
K
K
K
1/4W
1/4W
1/4W
R22,R50,R65,R70,R117
R25
5
1
R26
1
R27,R54,R79
R30
681
68.1
K
K
1/4W
1/4W
3
1
R34,R40,R52,R76,R139,R146,R157,R158,R162
9
2
1
1
1
5
1
51.1
9.09
1
150
K
1/4W
R37,R148
R38
R46
R48
R49,R55,R138,R140,R151
R56,R150
K
K
1/4W
1/4W
M
1/4W
1/4W
K
475 1/4W
681 1/4W
2
1.82
3.32
2.43
K
K
K
1/4W
1/4W
1/4W
R57
R58
R59
1
1
1
R61
332 1/4W
243 1/4W
267 1/4W
1
1
4
R62
R64,R69,R125,R142
R74,R81,R82,R83,R84,R85,R86,
R87,R88,R89,R90,R92,R93,R94,
R95,R97,R99,R101,R103,R105,
R107,R109,R111,R113,R115,R118,
R119,R120,R134,R135,R136,R160
R78,R124
100 1/4W
32
2
1
1
47.5
16.2
K
K
1/4W
1/4W
R91
R128
10K 10T
R129,R154
2
3
1K 1T
R132,R137,R144
500 10T
R141,R155
100
K
1/4W
2
VOLTAGE REG
BINARY COUNTER, STAGE
X1
X2
X3,X23
X4
X5
1
1
2
1
1
1
2
4
2
3
1
2
2
2
4
HC08A AND GATE
IC-CMOS,MCU,DSP,320
ROM ASBLY
ROM ASBLY
X6
X7,X10
X11,X12,X40,X42
X13,X14
X15,X21,X22
X16
X17,X18
X19,X24
X20,X38
X25
X26
X27
X28,X29,X31
X30
12 STAGE BINARY COUNTER
HC373A LATCH
3
STATE
HC259 DECODER
8
BIT SHIFT REG
8-BIT MPU D/A
HC4351
8
CHAN ANALOG MUX
HC109 FLIP FLOP
2
INPUT NAND GATE QUAD
NPN DARLINGTON ARRAY
224N QUAD OP AMP
OP-27GZ OP AMP
33074A OP AMP
1
1
3
HC4066
X32
X33
X34
HC04A INVERTER
1
1
1
1
1
1
2
1
431
I
VOLT REF
AC04 INVERTER
X35
X36
X37
X39,X41
Y1
AC139 DECODER
AC373
3
STATE LATCH
AC138 DECODER
HC74 FLIP FLOP
19.66 mHz.
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
G-14
G-14
ELECTRICAL DIAGRAMS
Meter PC Board (M15893) Layout
.022/50
330pf/100
1N4004
6
2
1
C5,C6
D1
METER
1
D2
1N914
J7
HEADER
LED DISPLAY
1
LED1,LED2,LED3
3
Q1
R1
1
1
1
475 1/4W
3.32K 1/4W
R2
R3,R4,R5,R6,R7,R8,R9,
R10,R11,R12,R13,R14,R15,
R16,R17,R18,R19,R20,R21,
R22,R23,R24,R25,R26
M15893
100 1/4W
24
3.01 1/4W
S.S.
S.S.
2
3
1
R27,R28
X1,X2,X3
X4
X5
S.S.
1
M15893
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
SQUARE WAVE TIG 355
Download from Www.Somanuals.com. All Manuals Search And Download.
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