Lincoln Electric Power Mig 255 Svm144 B Users Manual

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POWER MIG 255
SVM144-B
July, 2006
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 READ-
ING THIS MANUAL AND THE
SAFETY PRECAUTIONS CON-
TAINED THROUGHOUT. And,
most importantly, think before
you act and be careful.
SERVICE MANUAL
For use with machines having Code Number : 10563, 10583,10986, 10990
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• Sales and Service through Subsidiaries and Distributors Worldwide •
Cleveland, Ohio 44117-1199 U.S.A. TEL: 216.481.8100 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com
• World's Leader in Welding and Cutting Products •
Copyright © 2006 Lincoln Global Inc.
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i
SAFETY
i
LN-15
FOR ENGINE
powered equipment.
1.a. Turn the engine off before troubleshooting and maintenance
work unless the maintenance work requires it to be running.
____________________________________________________
1.b.Operate engines in open, well-ventilated
areas or vent the engine exhaust fumes
outdoors.
____________________________________________________
1.c. Do not add the fuel near an open flame weld-
ing arc or when the engine is running. Stop
the engine and allow it to cool before refuel-
ing 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.
____________________________________________________
1.d. Keep all equipment safety guards, covers and devices in posi-
tion and in good repair.Keep hands, hair, clothing and tools
away from V-belts, gears, fans and all other moving parts
when starting, operating or repairing equipment.
____________________________________________________
1.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.
___________________________________________________
1.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.
___________________________________________________
1.g. To prevent accidentally starting gasoline engines while
turning the engine or welding generator during maintenance
work, disconnect the spark plug wires, distributor cap or
magneto wire as appropriate.
ARC WELDING CAN BE HAZARDOUS. PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH.
KEEP CHILDREN AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.
Read and understand the following safety highlights. For additional safety information, it is strongly recommended that you
purchase a copy of “Safety in Welding & Cutting - ANSI Standard Z49.1” from the American Welding Society, P.O. Box 351040,
Miami, Florida 33135 or CSA Standard W117.2-1974. A Free copy of “Arc Welding Safety” booklet E205 is available from the
Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199.
BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE AND REPAIR PROCEDURES ARE
PERFORMED ONLY BY QUALIFIED INDIVIDUALS.
WARNING
Mar ‘95
ELECTRIC AND
MAGNETIC FIELDS
may be dangerous
2.a. Electric current flowing through any conductor causes
localized Electric and Magnetic Fields (EMF). Welding
current creates EMF fields around welding cables and
welding machines
2.b. EMF fields may interfere with some pacemakers, and
welders having a pacemaker should consult their physician
before welding.
2.c. Exposure to EMF fields in welding may have other health
effects which are now not known.
2.d. All welders should use the following procedures in order to
minimize exposure to EMF fields from the welding circuit:
2.d.1.
Route the electrode and work cables together - Secure
them with tape when possible.
2.d.2. Never coil the electrode lead around your body.
2.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.
2.d.4. Connect the work cable to the workpiece as close as
possible to the area being welded.
2.d.5. Do not work next to welding power source.
1.h. To avoid scalding, do not remove the
radiator pressure cap when the engine is
hot.
CALIFORNIA PROPOSITION 65 WARNINGS
Diesel engine exhaust and some of its constituents
are known to the State of California to cause can-
cer, birth defects, and other reproductive harm.
The engine exhaust from this product contains
chemicals known to the State of California to cause
cancer, birth defects, or other reproductive harm.
The Above For Diesel Engines The Above For Gasoline Engines
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ii
SAFETY
ii
LN-15
ARC RAYS can burn.
4.a. Use a shield with the proper filter and cover
plates to protect your eyes from sparks and
the rays of the arc when welding or observing
open arc welding. Headshield and filter lens
should conform to ANSI Z87. I standards.
4.b. Use suitable clothing made from durable flame-resistant
material to protect your skin and that of your helpers from
the arc rays.
4.c. Protect other nearby personnel with suitable, non-flammable
screening and/or warn them not to watch the arc nor expose
themselves to the arc rays or to hot spatter or metal.
ELECTRIC SHOCK can kill.
3.a. The electrode and work (or ground) circuits
are electrically “hot” when the welder is on.
Do not touch these “hot” parts with your bare
skin or wet clothing. Wear dry, hole-free
gloves to insulate hands.
3.b. Insulate yourself from work and ground using dry insulation.
Make certain the insulation is large enough to cover your full
area of physical contact with work and ground.
In addition to the normal safety precautions, if welding
must be performed under electrically hazardous
conditions (in damp locations or while wearing wet
clothing; on metal structures such as floors, gratings or
scaffolds; when in cramped positions such as sitting,
kneeling or lying, if there is a high risk of unavoidable or
accidental contact with the workpiece or ground) use
the following equipment:
• Semiautomatic DC Constant Voltage (Wire) Welder.
• DC Manual (Stick) Welder.
• AC Welder with Reduced Voltage Control.
3.c. In semiautomatic or automatic wire welding, the electrode,
electrode reel, welding head, nozzle or semiautomatic
welding gun are also electrically “hot”.
3.d. Always be sure the work cable makes a good electrical
connection with the metal being welded. The connection
should be as close as possible to the area being welded.
3.e. Ground the work or metal to be welded to a good electrical
(earth) ground.
3.f.
Maintain the electrode holder, work clamp, welding cable and
welding machine in good, safe operating condition. Replace
damaged insulation.
3.g. Never dip the electrode in water for cooling.
3.h. Never simultaneously touch electrically “hot” parts of
electrode holders connected to two welders because voltage
between the two can be the total of the open circuit voltage
of both welders.
3.i. When working above floor level, use a safety belt to protect
yourself from a fall should you get a shock.
3.j. Also see Items 6.c. and 8.
FUMES AND GASES
can be dangerous.
5.a. Welding may produce fumes and gases
hazardous to health. Avoid breathing these
fumes and gases.When welding, keep
your head out of the fume. Use enough
ventilation and/or exhaust at the arc to keep
fumes and gases away from the breathing zone. When
welding with electrodes which require special
ventilation such as stainless or hard facing (see
instructions on container or MSDS) or on lead or
cadmium plated steel and other metals or coatings
which produce highly toxic fumes, keep exposure as
low as possible and below Threshold Limit Values (TLV)
using local exhaust or mechanical ventilation. In
confined spaces or in some circumstances, outdoors, a
respirator may be required. Additional precautions are
also required when welding on galvanized steel.
5.b.
Do not weld in locations near chlorinated hydrocarbon
vapors
coming from degreasing, cleaning or spraying operations.
The heat and rays of the arc can react with solvent vapors
to
form phosgene, a highly toxic gas, and other irritating prod-
ucts.
5.c. Shielding gases used for arc welding can displace air and
cause injury or death. Always use enough ventilation,
especially in confined areas, to insure breathing air is safe.
5.d. Read and understand the manufacturer’s instructions for this
equipment and the consumables to be used, including the
material safety data sheet (MSDS) and follow your
employer’s safety practices. MSDS forms are available from
your welding distributor or from the manufacturer.
5.e. Also see item 1.b.
Mar ‘95
POWER MIG 255
SAFETY
iii iii
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FOR ELECTRICALLY
powered equipment.
8.a. Turn off input power using the disconnect
switch at the fuse box before working on
the equipment.
8.b. Install equipment in accordance with the U.S. National
Electrical Code, all local codes and the manufacturer’s
recommendations.
8.c. Ground the equipment in accordance with the U.S. National
Electrical Code and the manufacturer’s recommendations.
CYLINDER may explode
if damaged.
7.a. Use only compressed gas cylinders
containing the correct shielding gas for the
process used and properly operating
regulators designed for the gas and
pressure used. All hoses, fittings, etc. should be suitable for
the application and maintained in good condition.
7.b. Always keep cylinders in an upright position securely
chained to an undercarriage or fixed support.
7.c. Cylinders should be located:
•Away from areas where they may be struck or subjected to
physical damage.
•Asafe distance from arc welding or cutting operations and
any other source of heat, sparks, or flame.
7.d. Never allow the electrode, electrode holder or any other
electrically “hot” parts to touch a cylinder.
7.e. Keep your head and face away from the cylinder valve outlet
when opening the cylinder valve.
7.f. Valve protection caps should always be in place and hand
tight except when the cylinder is in use or connected for
use.
7.g. Read and follow the instructions on compressed gas
cylinders, associated equipment, and CGA publication P-l,
“Precautions for Safe Handling of Compressed Gases in
Cylinders,” available from the Compressed Gas Association
1235 Jefferson Davis Highway, Arlington, VA 22202.
Mar ‘95
WELDING SPARKS can
cause fire or explosion.
6.a.
Remove fire hazards from the welding area.
If this is not possible, cover them to prevent
the welding sparks from starting a fire.
Remember that welding 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.
6.b. Where compressed gases are to be used at the job site,
special precautions should be used to prevent hazardous
situations. Refer to “Safety in Welding and Cutting” (ANSI
Standard Z49.1) and the operating information for the
equipment being used.
6.c. When not welding, make certain no part of the electrode
circuit is touching the work or ground. Accidental contact can
cause overheating and create a fire hazard.
6.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).
6.e. Vent hollow castings or containers before heating, cutting or
welding. They may explode.
6.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
ear plugs when welding out of position or in confined places.
Always wear safety glasses with side shields when in a
welding area.
6.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.h. Also see item 1.c.
POWER MIG 255
SAFETY
iv iv
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PRÉCAUTIONS DE SÛRETÉ
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:
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 toujours
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.
b. Faire trés attention de bien s’isoler de la masse quand on
soude dans des endroits humides, ou sur un plancher met-
allique 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.
c. Maintenir le porte-électrode, la pince de masse, le câble de
soudage et la machine à souder en bon et sûr état defonc-
tionnement.
d.Ne jamais plonger le porte-électrode dans l’eau pour le
refroidir.
e. Ne jamais toucher simultanément les parties sous tension
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.
f. Si on utilise la machine à souder comme une source de
courant pour soudage semi-automatique, ces precautions
pour le porte-électrode s’applicuent aussi au pistolet de
soudage.
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
enrouler le câble-électrode autour de n’importe quelle partie du
corps.
3. Un coup d’arc peut être plus sévère qu’un coup de soliel, donc:
a. Utiliser un bon masque avec un verre filtrant approprié ainsi
qu’un verre blanc afin de se protéger les yeux du rayon-
nement 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 rayonnement de l‘arc.
c. Protéger l’autre personnel travaillant à proximité au
soudage à l’aide d’écrans appropriés et non-inflammables.
4. Des gouttes de laitier en fusion sont émises de l’arc de
soudage. Se protéger avec des 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 tout risque d’incendie dû aux étincelles.
7. Quand on ne soude pas, poser la pince à une endroit isolé de
la masse. Un court-circuit accidental peut provoquer un
échauffement et un risque d’incendie.
8. S’assurer que la masse est connectée le plus prés possible de
la zone de travail qu’il est pratique de le 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 autres circuits. Cela peut provoquer des
risques d’incendie ou d’echauffement des chaines et des
câbles jusqu’à ce qu’ils se rompent.
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 fumeés toxiques.
10. Ne pas souder en présence de vapeurs de chlore provenant
d’opérations 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 fortement toxique)
ou autres produits irritants.
11. Pour obtenir de plus amples renseignements sur la sûreté, voir
le code “Code for safety in welding and cutting” CSA Standard
W 117.2-1974.
PRÉCAUTIONS DE SÛRETÉ POUR
LES MACHINES À SOUDER À
TRANSFORMATEUR ET À
REDRESSEUR
1. Relier à la terre le chassis du poste conformement au code de
l’électricité et aux recommendations du fabricant. Le dispositif
de montage ou la piece à souder doit être branché à une
bonne mise à la terre.
2. Autant que possible, I’installation et l’entretien du poste seront
effectués par un électricien qualifié.
3. Avant de faires des travaux à l’interieur de poste, la debranch-
er à l’interrupteur à la boite de fusibles.
4. Garder tous les couvercles et dispositifs de sûreté à leur place.
POWER MIG 255
vv
MASTER TABLE OF CONTENTS FOR ALL SECTIONS
Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i-iv
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section A
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section B
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section C
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section D
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section E
Troubleshooting and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section F
Electrical Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section G
Parts Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .P344 Series
RETURN TO MAIN MENU
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X
Section A-1 Section A-1
TABLE OF CONTENTS
- INSTALLATION SECTION -
Installation ..............................................................................................................Section A
Technical Specifications...............................................................................................A-2
Safety Precautions .......................................................................................................A-3
Uncrating the POWER MIG 255...................................................................................A-3
Location........................................................................................................................A-3
Input Power, Grounding and Connection Diagrams ....................................................A-3
Output Polarity Connections........................................................................................A-5
Gun and Cable Installation...........................................................................................A-6
Shielding Gas ...............................................................................................................A-6
POWER MIG 255
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A-2
INSTALLATION
A-2
75°C Copper Wire 75°C Copper Wire
in Conduit in Conduit
Input Ampere AWG (IEC) Sizes AWG (IEC) Sizes
Input Voltage/ Fuse or Breaker Rating On (For lengths (For lengths
Frequency (Hz) Size (Super Lag) Nameplate up to 100 ft) exceeding 100 ft)
208/60 60 50 8 (10 mm2)6 (16 mm2)
230/60 60 46 10 (6 mm2)8 (10 mm2)
460/60 30 24 14 (2.5 mm2)12 (4 mm2)
575/60 25 19 14 (2.5 mm2)12 (4 mm2)
NOTE: Use #10 AWG Grounding Wire
TECHNICAL SPECIFICATIONS – POWER MIG 255
INPUT – SINGLE PHASE ONLY
RATED OUTPUT
OUTPUT
RECOMMENDED INPUT WIRE AND FUSE SIZES
Height Width Depth Weight
31.79 in. 18.88 in. 38.78 in. 220 Ibs
808 mm 480 mm 985 mm 100 kg
PHYSICAL DIMENSIONS
Wire Speed 50 – 700 IPM (1.27 – 17.8 m/minute)
WIRE SPEED RANGE
Standard Voltage/Frequency
Input Current @ 200 Amp Rated Output Input Current @ 250 Amp Rated Output
208/230/60 Hz 41/37 Amps 50/46
230/460/575/60 Hz 41/20/16 Amps 50/24/19
Duty Cycle Amps Volts at Rated Amperes
40% 250 Amps 26 Volts
60% 200 Amps 28 Volts
100% 145 Amps 26 Volts
Welding Current Range Maximum Open Circuit Voltage Welding Voltage Range
(Continuous)
30 – 300 Amps 40 Volts 10-28 Volts
POWER MIG 255
INSTALLATION
A-3 A-3
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INPUT POWER, GROUNDING AND
CONNECTION DIAGRAMS
------------------------------------------------------------------------
1. Before starting the installation, check with the
local power company if there is any question
about whether your power supply is adequate for
the voltage, amperes, phase, and frequency spec-
ified on the welder nameplate. Also be sure the
planned installation will meet the U.S. National
Electrical Code and local code requirements. This
welder may be operated from a single phase line
or from one phase of a two or three phase line.
2. Models that have multiple input voltages specified
on the nameplate (e.g. 208/230) are shipped con-
nected for the highest voltage. If the welder is to
be operated on lower voltage, it must be recon-
nected according to the instructions in Figure A.1
for dual voltage machines and Figure A.2 for
triple voltage machines.
Make certain that the input power is electrically
disconnected before removing the screw on the
reconnect panel access cover.
------------------------------------------------------------------------
Read entire installation section before starting
installation.
SAFETY PRECAUTIONS
ELECTRIC SHOCK can kill.
• Only qualified personnel should perform this
installation.
• Only personnel that have read and under-
stood the POWER MIG 255 Operating
Manual should install and operate this equip-
ment.
• Machine must be grounded per any national,
local or other applicable electrical codes.
• The POWER MIG power switch is to be in the
OFF position when installing work cable and
gun and when connecting other equipment.
WARNING
------------------------------------------------------------------------
UNCRATING THE POWER MIG 255
Cut banding and lift off cardboard carton. Cut banding
holding the machine to the skid. Remove foam and cor-
rugated packing material. Untape accessories from
Gas Bottle Platform. Unscrew the two wood screws (at
the Gas Bottle Platform) holding the machine to the
skid. Roll the machine off the skid assembly.
LOCATION
Locate the welder in a dry location where there is free
circulation of clean air into the louvers in the back and
out the front. A location that minimizes the amount of
smoke and dirt drawn into the rear louvers reduces the
chance of dirt accumulation that can block air pas-
sages and cause overheating.
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts such as
output terminals or internal wiring.
• All input power must be electrically discon-
nected before proceeding.
WARNING
WARNING
POWER MIG 255
INSTALLATION
A-4 A-4
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4. Using the instructions in Figure A.3, have a qual-
ified electrician connect the receptacle or cable to
the input power lines and the system ground per
the U.S. National Electrical Code and any applic-
able local codes. See Technical Specifications
at the beginning of this chapter for proper wire
sizes. For long runs over 100 feet, larger copper
wires should be used. Fuse the two hot lines with
super lag type fuses as shown in the following dia-
gram. The center contact in the receptacle is for
the grounding connection. A green wire in the
input cable connects this contact to the frame of
the welder. This ensures proper grounding of the
welder frame when the welder plug is inserted into
the receptacle.
3. The 208/230 volt 60 Hz model POWER MIG is
shipped with a 10 ft. input cable and plug con-
nected to the welder. A matching receptacle is
supplied with the machine. Mount the receptacle
in a suitable location using the screws provided.
Be sure it can be reached by the plug on the input
cable attached to the welder. Mount with the
grounding terminal at the top to allow the power
cable to hang down without bending.
The 230/460/575 volt 60 Hz model is not
equipped with a plug, an input cable, or a
receptacle.
FIGURE A.1 — DUAL VOLTAGE MACHINE INPUT CONNECTIONS.
POWER MIG 255
INSTALLATION
A-5 A-5
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FIGURE A.3 — RECEPTACLE DIAGRAM.
CONNECT TO A SYSTEM
GROUNDING WIRE. SEE
THE UNITED STATES
NATIONAL ELECTRICAL
CODE AND/OR LOCAL
CODES FOR OTHER
DETAILS AND MEANS FOR
PROPER GROUNDING.
CONNECT TO HOT WIRES
OF A THREE-WIRE, SINGLE
PHASE SYSTEM OR TO ONE
PHASE OF A TWO OR
THREE PHASE SYSTEM.
OUTPUT POLARITY CONNECTIONS
The welder, as shipped from the factory, is connected
for electrode positive (+) polarity. This is the normal
polarity for GMA welding.
If negative (–) polarity is required, interchange the con-
nection of the two cables located in the wire drive com-
partment near the front panel. The electrode cable,
which is attached to the wire drive, is to be connected
to the negative (–) labeled terminal. The work lead,
which is attached to the work clamp, is to be connect-
ed to the positive (+) labeled terminal.
FIGURE A.2 — TRIPLE VOLTAGE MACHINE INPUT CONNECTIONS.
POWER MIG 255
INSTALLATION
A-6 A-6
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GUN AND CABLE INSTALLATION
The Magnum 250L gun and cable provided with the
POWER MIG 255 is factory installed with a liner for
0.035-0.045 in. (0.9-1.2 mm) electrode and an 0.035
in. (0.9 mm) contact tip. Install the 0.045 tip (also pro-
vided) if this wire size is being used.
Turn the welder power switch off before installing
gun and cable.
------------------------------------------------------------------------
1. Lay the cable out straight.
2. Unscrew knurled screw on the drive unit front end
(inside wire feed compartment) until tip of screw
no longer protrudes into gun opening as seen
from front of machine.
3. Insert the male end of gun cable into the female
casting through opening in front panel. Make sure
connector is fully inserted and tighten knurled
screw.
4. Connect the gun trigger connector from the gun
and cable to the mating receptacle inside the
compartment located above the gun connection
made in item 3 above. Make sure that the key-
ways are aligned, insert and tighten retaining ring.
SHIELDING GAS
(For Gas Metal Arc Welding Processes)
Customer must provide cylinder of appropriate type
shielding gas for the process being used.
Agas flow regulator, for CO2or Argon blend gas, and
an inlet gas hose are factory provided with the POWER
MIG 255. Install the shielding gas supply as follows:
1. Set gas cylinder on rear platform of POWER MIG
255. Hook chain in place to secure cylinder to rear
of welder.
2. Remove the cylinder cap. Inspect the cylinder
valves and regulator for damaged threads, dirt,
dust, oil or grease. Remove dust and dirt with a
clean cloth.
DO NOT ATTACH THE REGULATOR IF OIL,
GREASE OR DAMAGE IS PRESENT! Inform
your gas supplier of this condition. Oil or grease
in the presence of high pressure oxygen is
explosive.
------------------------------------------------------------------------
3. Stand to one side away from the outlet and open
the cylinder valve for an instant. This blows away
any dust or dirt which may have accumulated in
the valve outlet.
Be sure to keep your face away from the valve out-
let when “cracking” the valve.
------------------------------------------------------------------------
4. Attach the flow regulator to the cylinder valve and
tighten the union nut(s) securely with a wrench.
NOTE: If connecting to 100% CO2cylinder, insert
regulator adapter between regulator and cylinder
valve. If adapter is equipped with a plastic washer, be
sure it is seated for connection to the CO2cylinder.
5. Attach one end of the inlet gas hose to the outlet
fitting of the flow regulator, the other end to the
POWER MIG 255 rear fitting, and tighten the
union nuts securely with a wrench.
6. Before opening the cylinder valve, turn the regu-
lator adjusting knob counterclockwise until the
adjusting spring pressure is released.
7. Standing to one side, open the cylinder valve
slowly a fraction of a turn. When the cylinder pres-
sure gauge pointer stops moving, open the valve
fully.
Never stand directly in front of or behind the flow
regulator when opening the cylinder valve. Always
stand to one side.
------------------------------------------------------------------------
8. The flow regulator is adjustable. Adjust it to the
flow rate recommended for the procedure and
process being used before making the weld.
WARNING
WARNING
CYLINDER may explode if
damaged.
• Gas under pressure is explosive. Always keep
gas cylinders in an upright position and always
keep chained to undercarriage or stationary
support. See American National Standard Z-
49.1, “Safety in Welding and Cutting” pub-
lished by the American Welding Society.
WARNING
WARNING
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POWER MIG 255
Section B-1 Section B-1
TABLE OF CONTENTS
- OPERATION SECTION -
Operation ................................................................................................................Section B
Product Description......................................................................................................B-3
Recommended Processes and Equipment..................................................................B-3
Welding Capability........................................................................................................B-3
Limitations ....................................................................................................................B-3
Description of Controls ................................................................................................B-4
Wire Drive Roll..............................................................................................................B-4
Wire Size Conversion Parts..........................................................................................B-4
Procedure for Changing Drive and Idle Roll Sets ........................................................B-5
Wire Reel Loading - Readi-Reels, Spools, or Coils .....................................................B-5
To Mount a 30 lb (14 kg) Readi-Reel Package
(Using the Molded Plastic K363-P Readi-Reel Adapter).......................................B-5
To Mount 10 to 44 lb (4.5-20 kg) Spools (12 in./300 mm Diameter)
or 14 lb (6 kg) Innershield Coils .............................................................................B-5
To Start the Welder.......................................................................................................B-6
Feeding Wire Electrode................................................................................................B-6
Idle Roll Pressure Setting .............................................................................................B-6
Setting Run-In Speed on Standard Power MIG Feeder ..............................................B-6
Fast or Slow Run-In Mode Selection (When Timer Option is not Installed)..........B-6
Instructions to Enter Slow Run-In..........................................................................B-6
Instructions to Enter Fast Run-In...........................................................................B-6
Making a Weld..............................................................................................................B-7
Avoiding Wire Feeding Problems .................................................................................B-7
Fan Control...................................................................................................................B-8
Input Line Voltage Protection.......................................................................................B-8
Wire Feed Overload Protection ....................................................................................B-8
Welding Thermal Overload Protection .........................................................................B-8
Overcurrent Protection .................................................................................................B-8
POWER MIG 255
OPERATION
B-2 B-2
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Read entire Operation section before
operating the POWER MIG 255.
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts
or electrode with skin or wet
clothing. Insulate yourself from
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 closed containers.
ARC RAYS can burn eyes and
skin.
• Wear eye, ear and body protec-
tion.
Observe all safety information throughout
this manual.
WARNING
POWER MIG 255
OPERATION
B-3 B-3
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PRODUCT DESCRIPTION
The POWER MIG™ 255 is a complete semiautomatic
constant voltage DC arc welding machine built to meet
NEMA specifications. It combines a constant voltage
power source and a constant speed wire feeder with a
microcomputer-based controller to form a reliable high-
performance welding system. A simple control scheme,
consisting of continuous full range voltage and wire
feed speed controls, provides versatility with ease of
use and accuracy.
Other features include a 2 in. (51 mm) O.D. wire reel
spindle with adjustable brake, an integral gas cylinder
mounting undercarriage, an adjustable CO2or Argon
blend flow regulator with cylinder pressure gauge and
inlet hose, a 12 ft (3.6 m) Magnum 250L GMAW gun
and cable with fixed (flush) nozzle, a 10 ft (3.0 m)
power cable with plug and mating receptacle, and a 10
ft (3.0 m) work cable with clamp.
An Optional Timer kit provides variable burnback con-
trol, a spot function, a selectable 4-step trigger inter-
lock and adjustable “Run In” for wire starting optimiza-
tion. Also optional are a Spool Gun Adapter kit, a Dual
Cylinder Mounting Kit and an Aluminum Feeding Kit for
push feeding with standard built in feeder.
RECOMMENDED PROCESSES
AND EQUIPMENT
The POWER MIG 255 is recommended for GMA
welding processes using 10 to 44 lb (4.5 to 20 kg)
2in. (51 mm) I.D. spools or Readi-Reel®coils (with
optional adapter) of 0.025 in. through 0.045 in.
(0.6 to 1.2 mm) solid steel, 0.035 in. (0.9 mm)
stainless, 3/64 in. (1.2 mm) aluminum and 0.045 in.
(1.2 mm) Outershield®; as well as 0.035 in. (0.9 mm)
and 0.045 in. (1.2 mm) Innershield®self-shielding
electrodes.
The POWER MIG is factory equipped to feed
0.035 in. (0.9 mm) electrodes and provides tip, guide,
and drive rolls for 0.045 in. (1.2 mm) electrode. It also
includes a 200A, 60% duty cycle (or 250A, 40% duty
cycle) rated, 12 ft (3.6 m) GMAW gun and cable
assembly equipped for these wire sizes. Use of GMAW
processes requires a supply of shielding gas.
WELDING CAPABILITY
The POWER MIG 255 is rated at 250 amps @ 26 volts,
at a 40% duty cycle based on a ten minute cycle time.
It is capable of higher duty cycles at lower output cur-
rents and capable of up to 300 Amps at lower duty
cycles.
LIMITATIONS
The POWER MIG 255 MAY NOT operate
satisfactorily if powered with a portable or in-plant
generating system.
POWER MIG 255
OPERATION
B-4 B-4
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DESCRIPTION OF CONTROLS
Power ON/OFF Switch — Place the lever in the “ON”
position to energize the POWER MIG 255. When the
power is on, the red LED display lights illuminate.
Voltage Control — This is a continuous control that
gives full range adjustment of power source output volt-
age. It can be adjusted while welding over its 10 to 28
volt range.
Wire Speed Control — This controls the wire feed
speed from 50 to 700 inches per minute (1.2 to
17.8 m/min). The wire speed control can be preset on
the dial to the setting specified on the Procedure Decal
located inside the wire compartment door. Wire speed
is not affected when changes are made in the voltage
control.
WIRE DRIVE ROLL
The drive rolls installed with the POWER MIG each
have two grooves, both for 0.030-0.0035 in.
(0.8-0.9 mm) solid steel electrode. Drive roll size is indi-
cated by the stencilling on the exposed side of the drive
roll. If feeding problems occur, then the drive roll may
be reversed or changed. See Procedure for
Changing Drive Roll in this section. This information
also appears on the Procedure Decal on the door
inside the wire compartment. An additional drive roll set
is provided for 0.045 in. (1.2 mm) solid steel electrode,
packaged standard with each machine.
WIRE SIZE CONVERSION PARTS
The POWER MIG 255 is rated to feed 0.025 through
0.045 in. (0.6 to 1.2 mm) solid or cored electrode sizes.
The drive roll kits and Magnum 250L gun and cable
parts are available to feed different sizes and types of
electrodes. See Accessories section.
FIGURE B.1 — OPERATOR CONTROLS
POWER
POWER MIG 255
WIRE SPEED
ON
OFF
VOLTS
LINCOLN
ELECTRIC
POWER MIG 255
OPERATION
B-5 B-5
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PROCEDURE FOR CHANGING
DRIVE AND IDLE ROLL SETS
1. Turn off the power source.
2. Release the pressure on the idle roll by swinging
the adjustable pressure arm down toward the
back of the machine. Lift the cast idle roll assem-
bly and allow it to sit in an upright position.
3. Remove the outside wire guide retaining plate by
loosening the two large knurled screws.
4. Twist the drive roll retaining mechanism to the
unlocked position.
5. Wiggle both the metal idle and drive rolls off of
their plastic hubs.
6. Remove the inside wire guide plate.
7. Replace the drive and idle rolls and inside wire
guide with a set marked for the new wire size.
NOTE: Be sure that the gun liner and contact tip are
also sized to match the selected wire size.
8. Manually feed the wire from the wire reel, over the
drive roll groove and through the wire guide and
then into the brass bushing of the gun and cable
assembly.
9. Replace the outside wire guide retaining plate by
tightening the two large knurled screws.
Reposition the adjustable pressure arm to its orig-
inal position to apply pressure. Adjust pressure as
necessary.
WIRE REEL LOADING -
READI-REELS, SPOOLS, OR COILS
To Mount a 30 lb (14 kg) Readi-Reel
Package (Using the Molded Plastic K363-P
Readi-Reel Adapter:)
1. Open the wire drive compartment door.
2. Depress the release bar on the retaining collar
and remove it from the spindle. See Figure B.2.
3. Place the optional adapter on the spindle.
4. Re-install the retaining collar. Make sure that the
release bar “pops up” and that the collar retainers
fully engage the retaining ring groove on the
spindle.
5. Rotate the spindle and adapter so the retaining
spring is at the 12 o'clock position.
6. Position the Readi-Reel so that it will rotate in a
direction when feeding so as to be de-reeled from
top of the coil.
7. Set one of the Readi-Reel inside cage wires on
the slot in the retaining spring tab.
FIGURE B.2 — READI-REEL INSTALLATION.
8. Lower the Readi-Reel to depress the retaining
spring and align the other inside cage wires with
the grooves in the molded adapter.
9. Slide cage all the way onto the adapter until the
retaining spring “pops up” fully.
Check to be sure the retaining spring has fully returned
to the locking position and has securely locked the
Readi-Reel cage in place. The retaining spring must
rest on the cage, not on the welding
electrode.
------------------------------------------------------------------------
10. To remove Readi-Reel from adapter, depress
retaining spring tab with thumb while pulling the
Readi-Reel cage from the molded adapter with
both hands. Do not remove adapter from spindle.
To Mount 10 to 44 lb (4.5-20 kg) Spools
(12 in./300 mm Diameter) or 14 lb
(6 kg) Innershield Coils:
(For 13-14 lb (6 kg) innershield coils, a K435 coil
adapter must be used).
1. Open the wire drive compartment door.
2. Depress the release bar on the retaining collar
and remove it from the spindle.
3. Place the spool on the spindle making certain the
spindle brake pin enters one of the holes in the
back side of the spool (Note: an arrow mark on the
spindle lines up with the brake holding pin to
assist in lining up a hole). Be certain the wire
comes off the reel in a direction that it can de-reel
from the top of the coil.
4. Re-install the retaining collar. Make sure that the
release bar “pops up” and that the collar retainers
fully engage the retaining ring groove on the
spindle.
2 IN. O.D.
SPINDLE ADAPTER
RETAINING
SPRING
BRAKE
HOLDING
PIN
GROOVES
READI-REEL
INSIDE
CAGE
WIRES RELEASE
BAR
RETAINING
COLLAR
CAUTION
POWER MIG 255
OPERATION
B-6 B-6
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TO START THE WELDER
Turn the Power Switch switch to ON. This lights the red
LED display lights. With the desired voltage and wire
speed selected, operate the gun trigger for welder out-
put and to energize the wire feed motor.
FEEDING WIRE ELECTRODE
When triggering, the electrode and drive mecha-
nism are electrically “hot” relative to work and
ground and remain “hot” several seconds after the
gun trigger is released.
------------------------------------------------------------------------
NOTE: Check that drive rolls, guide plates, and gun
parts are proper for the wire size and type being used.
Refer to Table C.1 in Accessories section.
1. Turn the Readi-Reel or spool until the free end of
the electrode is accessible.
2. While securely holding the electrode, cut off the
bent end and straighten the first six inches. (If the
electrode is not properly straightened, it may not
feed properly through the wire drive system.)
3. Release the pressure on the idle roll by swinging
the adjustable pressure arm down toward the
back of the machine. Lift the cast idle roll assem-
bly and allow it to sit in an upright position. Leave
the outer wire guide plate installed. Manually feed
the wire through the incoming guide bushing and
through the guide plates (over the drive roll
groove). Push a sufficient wire length to assure
that the wire has fed into the gun and cable
assembly without restriction. Reposition the
adjustable pressure arm to its original position to
apply pressure to the wire.
4. Press gun trigger to feed the electrode wire
through the gun.
IDLE ROLL PRESSURE SETTING
The idle roll pressure adjustment knob is set at the fac-
tory at the #2 hash mark. This is an approximate set-
ting. The optimum idle roll pressure varies with type of
wire, wire diameter, surface conditions, lubrication, and
hardness. As a general rule, hard wires may require
greater pressure, and soft, or aluminum wire, may
require less pressure than the factory setting. The opti-
mum idle roll setting can be determined as follows:
1. Press end of gun against a solid object that is
electrically isolated from the welder output and
press the gun trigger for several seconds.
2. If the wire “birdnests”, jams, or breaks at the drive
roll, the idle roll pressure is too great. Back the
adjustment knob out 1/2 turn, run new wire
through gun, and repeat above steps.
3. If the only result was drive roll slippage, loosen the
adjustment knob on the conductor plate and pull
the gun cable forward about 6 in. (15 cm). There
should be a slight waviness in the exposed wire. If
there is not waviness, the pressure is too low.
Tighten the adjustment knob 1/4 turn, reinstall the
gun cable and repeat the above steps.
SETTING RUN-IN SPEED ON STAN-
DARD POWER MIG FEEDER
FAST OR SLOW RUN-IN MODE SELECTION
(When Timer Option is not installed)
The POWER MIG 255 is factory set for fast run-in
mode where the wire feed will accelerate directly to the
preset wire feed speed when the gun trigger is closed.
Slow run-in mode may also be selected, where it will
initially feed wire at 50 IPM until output current is
sensed or for 1.0 second, whichever occurs first. It will
then accelerate to the preset wire feed speed.
NOTE: See operating instructions for Timer Option Kit
if it is installed, as it provides its own run-in operation.
INSTRUCTIONS TO ENTER SLOW RUN-IN
1. Turn power OFF on front panel of POWER MIG
255.
2. Turn the wire feed speed dial fully counterclock-
wise to minimum.
3. With the gun trigger closed, turn the power ON at
the front panel of the POWER MIG 255.
4. The display will read “SLO run”.
INSTRUCTIONS TO ENTER FAST RUN-IN
1. Turn power OFF on front panel of POWER MIG
255.
2. Turn the wire feed speed dial fully clockwise to
maximum.
3. With the gun trigger closed, turn the power ON at
the front panel of the POWER MIG 255.
4. The display will read “FAS run”.
WARNING
POWER MIG 255
OPERATION
B-7 B-7
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NOTE: Arc starting characteristics may be effected
when using the fast run-in mode since optimum start-
ing processes are being overridden.
On the initial trigger closure at power up, no output
power or wire feed will be available until the trigger is
opened and reclosed, regardless of wire feed speed
dial setting.
It is not necessary to repeat either of the above proce-
dures each time the unit is powered up. The unit will
remember the run-in mode from the previous power
down and return you to that same state upon your next
power up. Therefore, you need only perform one of the
above procedures when you want to change the run-in
mode.
MAKING A WELD
1. Check that the electrode polarity is correct for the
process being used, then turn the power switch
ON.
2. Set desired arc voltage and wire speed for the
particular electrode wire, material type and thick-
ness, and gas (for GMAW) being used. Use the
Application Chart on the door inside the wire com-
partment as a quick reference for some common
welding procedures.
3. If Timer Kit is installed, select the desired mode as
described in Operating Instructions for Timer
Kit in the Accessories section. Refer to the
Accessories section for additional welding infor-
mation pertaining to Spot mode.
4. Press the trigger to feed the wire electrode
through the gun and cable and then cut the elec-
trode within approximately 3/8 in. (10 mm) of the
end of the contact tip [3/4 in. (20 mm)
Outershield®].
NOTE: If set for slow run-in when the trigger is pulled,
the wire feeder feeds wire at low speed regardless of
the set wire feed speed until the welding arc starts or 1
second has elapsed. This feature enhances starting
and makes it easier to set the stickout. The 1 second
limit permits high speed loading of the gun and cable.
To change run-in mode, see Setting Run-In Speed in
this section, if the Timer Kit is not installed, or Timer Kit
Operation section if installed.
5. If welding gas is to be used, turn on the gas sup-
ply and set the required flow rate (typically 25-35
CFH; 12-16 liters/min).
6. When using innershield electrode, the gas nozzle
may be removed from the insulation on the end of
the gun and replaced with the gasless nozzle.
This will give improved visibility and eliminate the
possibility of the gas nozzle overheating.
7. Connect work cable to metal to be welded. Work
clamp must make good electrical contact to the
work. The work must also be grounded as stated
in Arc Welding Safety Precautions.
When using an open arc process, it is necessary
to use correct eye, head, and body protection.
------------------------------------------------------------------------
8. Position electrode over joint. End of electrode
may be lightly touching the work.
9. Lower welding helmet, close gun trigger, and
begin welding. Hold the gun so the contact tip to
work distance is about 3/8 in. (10 mm) [3/4 in.
(20 mm) for Outershield].
10. To stop welding, release the gun trigger and then
pull gun away from the work after arc goes out.
11. When no more welding is to be done, close valve
on gas cylinder (if used), momentarily operate gun
trigger to release gas pressure, and turn off
POWER MIG 255.
AVOIDING WIRE FEEDING
PROBLEMS
Wire feeding problems can be avoided by observing
the following gun handling procedures:
1. Do not kink or pull cable around sharp corners.
2. Keep the gun cable as straight as possible when
welding or loading electrode through cable.
3. Do not allow dolly wheels or trucks to run over
cables.
4. Keep cable clean by following the maintenance
instructions.
WARNING
POWER MIG 255
OPERATION
B-8 B-8
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5. Use only clean, rust-free electrode. The Lincoln
electrodes have proper surface lubrication.
6. Replace contact tip when the arc starts to become
unstable or the contact tip end is fused or
deformed.
7. Keep wire reel spindle brake tension to minimum
required to prevent excess reel over-travel which
may cause wire “loop-offs” from coil.
8. Use proper drive rolls and wire drive idle roll pres-
sure for wire size and type being used.
FAN CONTROL
The fan is designed to come on automatically when a
weld arc is established. The fan will stay on for a mini-
mum of 6 minutes after the weld arc is terminated. The
fan will also stay on when the machine’s welding and
feeding are disabled during thermostatic over temper-
ature protection. (See Welding Thermal Overload
Protection.)
INPUT LINE VOLTAGE
PROTECTION
High Line Voltage — If the line voltage exceeds 125%
of rated input voltage, the output will be reduced to the
lower level to protect voltage rating of the capacitor
bank.
Low Line Voltage — You may not be able to get max-
imum output from the machine if the line voltage is less
than rated input. The unit will continue to weld, but the
output may be less than what is set.
WIRE FEED OVERLOAD
PROTECTION
The POWER MIG has solid state overload protection
of the wire drive motor. If the motor becomes
overloaded, the protection circuitry turns off the wire
feed speed and gas solenoid. Check for proper size
tip, liner, and drive rolls, for any obstructions or bends
in the gun cable, and any other factors that would
impede the wire feeding. To resume welding, simply
pull the trigger. There is no circuit breaker to reset as
the protection is done with reliable solid state
electronics.
WELDING THERMAL
OVERLOAD PROTECTION
The POWER MIG 255 has built-in protective ther-
mostats that respond to excessive temperature. They
open the wire feed and welder output circuits if the
machine exceeds the maximum safe operating tem-
perature because of a frequent overload, or high ambi-
ent temperature plus overload. The thermostats auto-
matically reset when the temperature reaches a safe
operating level and welding and feeding are allowed
again, when gun is retriggered.
OVERCURRENT PROTECTION
The machine will automatically reduce the output if the
load on the machine exceeds 300 to 320 amperes.
This protects the welding power SCR’s from excessive
short circuit currents and from exceeding their temper-
ature rating before the thermostats can react.
Welding Procedure Information
Note: See inside cover of machine for additional, commonly used welding procedure information.
70 80 90 100 110 120
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POWER MIG 255
Section C-1 Section C-1
TABLE OF CONTENTS
- ACCESSORIES SECTION -
Accessories ............................................................................................................Section C
Drive Roll Kits ...............................................................................................................C-2
3/64 in. (1.2 mm) Aluminum Feeding Kit (K1703-1) .....................................................C-2
K363P Readi-Reel Adapter ..........................................................................................C-2
Dual Cylinder Mounting Kit (K1702-1)..........................................................................C-2
Alternative Magnum GMAW Gun and Cable Assemblies............................................C-2
Magnum Gun Connection Kit (Optional K466-6) .........................................................C-2
Timer Kit Installation (Optional K1701-1) .....................................................................C-2
Operating Instructions for Timer Kit.......................................................................C-3
Spool Gun Adapter Kit (K1700-1) (Included in the K1692-1).......................................C-4
Making a Weld with the Spool Gun, Spool Gun (K1692-1) Installed.....................C-4
POWER MIG 255
ACCESSORIES
C-2 C-2
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DRIVE ROLL KITS
Refer to Table C.1 for various drive roll kits that are
available for the POWER MIG. All items in Bold are
supplied standard with the POWER MIG.
TABLE C.1 — AVAILABLE DRIVE ROLL KITS.
3/64 in. (1.2 mm) ALUMINUM
FEEDING KIT (K1703-1)
This kit helps push feeding aluminum through standard
machine feeder and gun. It provides gun and wire drive
conversion parts to weld with 3/64 in.
(1.2 mm) aluminum wire. 5356 alloy aluminum wire is
recommended for best push feeding performance.
Kit includes drive rolls and wire guide plate for the wire
drive, liner and two contact tips for the gun, along with
installation instructions.
K363P READI-REEL ADAPTER
The K363P Readi-Reel adapter mounts to the
2 in. spindle. It is needed to mount the 22-30 lb Readi-
Reels.
DUAL CYLINDER
MOUNTING KIT (K1702-1)
Permits stable side-by-side mounting of two full size (9
in. dia. x 5 ft. high) gas cylinders with “no lift” loading.
Simple installation and easy instructions provided.
Includes upper and lower cylinder supports, wheel
axles and mounting hardware.
ALTERNATIVE MAGNUM GMAW
GUN AND CABLE ASSEMBLIES
The following Magnum 250L gun and cable assemblies
are separately available for use with the POWER MIG
255. Each is rated 200 amps 60% duty cycle (or 250
amps 40% duty) and is equipped with the integrated
connector, twist-lock trigger connector, fixed nozzle
and insulator, and includes a liner, diffuser, and contact
tips for the wire sizes specified:
*Fixed Nozzle
MAGNUM GUN CONNECTION KIT
(Optional K466-6)
Using the optional K466-6 Magnum Connection Kit for
the POWER MIG permits use of standard Magnum
200, 300 or 400 gun and cable assemblies.
TIMER KIT INSTALLATION
(Optional K1701-1)
The timer kit adds selectable 4-step trigger interlock,
spot and Run-In functions and manual adjustment of
burnback time. Install as follows, or per the instructions
included with the kit:
Remove all input power to the POWER MIG 255
before proceeding.
------------------------------------------------------------------------
1. Verify that the following items have been included
in the kit:
a. Timer board with harness and panel
assembly.
b. Two screws.
2. Turn the power switch off and disconnect power
from the machine to prepare for kit installation.
Wire Size Drive Roll Kit
0
.023-0.030 in. (0.6-0.8 mm)
KP1696-030S
Solid 0.035 in. (0.9 mm) KP1696-035S
Steel 0.045 in. (1.2 mm) KP1696-045S
Cored 0.035 in. (0.9 mm) KP1697-035C
0.045 in. (1.2 mm) KP1697-045C
Aluminum
3/64 in. (1.2 mm) KP1695-3/64A
WARNING
English Wire Metric Wire
Length Part No. Size Size
10 ft (3.0 m) K533-1
*12 ft (3.6 m) K533-7 0.035 – 0.045 in. 0.9 – 1.2 mm
15 ft (4.5 m) K533-3
POWER MIG 255
ACCESSORIES
C-3 C-3
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3. Using a screwdriver, remove the two screws
securing the lower cover panel to the front of the
machine. Remove the lower cover panel.
4. Attach the rectangular 10-pin plug connector on
the timer kit wiring harness to the mating recepta-
cle connector located directly behind the removed
cover panel. Be sure that the latch on the connec-
tor is aligned with the one on the board and insert
it until the latch engages.
5. Align the timer panel for installation and carefully
insert the printed circuit board and wiring harness
through the opening. Make sure the wiring har-
ness is not pinched between panels or between
printed circuit board and front panel cover.
6. Secure the timer assembly with either the two
supplied screws or with the original screws. The
installation is now complete. Refer to the following
section for operating instructions.
OPERATING INSTRUCTIONS
FOR TIMER KIT
If the optional Timer Kit (K1701-1) is installed, select
the desired mode with the selector switch:
1. Normal Welding mode provides weld power only
while the trigger switch is depressed. This is the
same operation as when the Timer Kit is not
installed.
2. 4-Step Trigger interlock mode eliminates the
need to hold the gun trigger while welding. It oper-
ates in 4 steps:
a. Close trigger and establish welding arc.
b. Release trigger and continue welding.
c. Reclose trigger near end of weld.
d. Release trigger again to stop welding.
If the arc is broken while using this feature, the
machine will reset to the “trigger off” condition
automatically.
3. Spot Weld Mode is used for tack welding parts
into position or for spot plug welds to hold thin
sheet metal together prior to manual stitch or con-
tinuous welding. To use this feature, adjust the
On-Time (0-5 seconds) as appropriate to obtain
the desired results. Closing the trigger initiates a
single timed spot weld cycle. Plug welds are made
by using a punch to make a 3/16 in. (5 mm) diam-
eter hole in the top sheet and arc welding through
the hole into the back sheet.
To make spot plug welds, punch 3/16 in. (5 mm)
holes in the top sheet. Set the Spot Time control
to approximately 1.2 seconds and set the proce-
dure for the metal thickness to be welded. Install
spot weld nozzle (if available) on gun and press it
against the top sheet so the top and bottom
sheets are tight together. Close trigger and hold it
closed until the arc goes out. If a spot weld nozzle
is not used, smoother welds will result by moving
the welding wire in a small circle during the weld.
4. Burnback Time control provides manual adjust-
ment of the burnback time (0-250 milliseconds) for
any selected welding mode. This control should
be set as low as possible without the wire “stick-
ing” in the puddle after each weld. Too long of a
burnback time may form a “ball” on the end of the
wire, or may “flash back” to the gun tip.
5. Run-In Mode is used to adjust the starting wire
feed speed. Starting conditions for certain welding
applications can be improved with adjustment to
the Run-In speed. The control allows for initial
starting speeds from 50 to 150 IPM. After the arc
is started, the set point on the wire feed speed
control will dominate. Note that the Run-in is not
functional with the spool gun. Also note that if
Run-in is set fully counterclockwise to OFF, Run-
in speed will equal the preset WFS on the
machine.
POWER MIG 255
ACCESSORIES
C-4 C-4
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SPOOL GUN ADAPTER KIT
Remove all input power to the POWER MIG 255
before proceeding.
------------------------------------------------------------------------
The Spool Gun Adapter Kit provides direct connection
and use of the Spool Gun (with remote speed control)
with the POWER MIG 255 wire feed welder.
It also provides gun trigger switch transfer between the
machine’s use with its feeder gun or the spool gun for
same polarity welding with different wire and gas
processes.
The kit includes a spool gun adapter module assembly
with a single connecting plug, a rear gas inlet setting
with hose and mounting hardware with installation and
operation instructions.
*This kit can only be configured to run a Magnum® SG
Spool Gun OR a Prince® XL Spool Gun at a time; kit is
shipped configured for the Magnum® SG Spool Gun.
MAKING A WELD WITH THE SPOOL GUN,
SPOOL GUN INSTALLED
The POWER MIG control circuitry is designed to
sense either the spool gun (built in) wire feeder trigger
circuitry. After the spool gun adapter kit has been
installed, the spool gun can easily be plugged in and
will be ready to use.
Closing either gun trigger will cause the electrode of
both guns to be electrically “HOT”. Be sure unused gun
is positioned so electrode or tip will not contact metal
case or other metal common to work.
1.Pulling the trigger for the built-in feeder gun:
a. Disables spool gun operation.
b. Closing feeder gun trigger starts feeder gun
welding and makes both electrodes electri-
cally “HOT”.
2. Pulling SPOOL GUN Trigger:
a. Disables built-in feeder gun operation.
b. Closing spool gun trigger starts spool gun
welding and makes both electrodes electri-
cally “HOT”.
3. Operation with POWER MIG 255:
a. Turn the POWER MIG-255 input power
ON.
b. Adjust the voltage control to increase or
decrease your welding voltage.
c. Adjust the wire speed control on the spool
gun to increase or decrease the spool gun
wire feed speed.
4. The following procedure settings for Aluminum
4043 can be used as initial settings for making
test welds to determine final settings:
5. To return to normal POWER MIG 255 welding
release the spool gun trigger and reset feeder
gun voltage procedure setting if necessary.
6. Operation with Timer Option Kit (K1701-1)
installed in Power MIG 255:
All Timer Option Kit functions, except Run-in,
are functional with the spool gun. (See operat-
ing instructions for Timer Option Kit.
WARNING
CAUTION
Wire Dia. WFS Setting Arc Voltage
In. (mm) Spool Gun Setting
0.030 in. (0.8 mm) 270 15V
0.035 in. (0.9 mm) 250 16V
3/64 in. (1.2 mm) 240 20V
K2297-1
K2310-1*
Prince®XL Spool Gun with Adaptor Included
Power MIG 255 Spool Gun Adaptor Kit
(connects Magnum®SG Spool Gun OR
Prince®XL Spool Gun
K487-25 Magnum®SG Spool Gun (requires K2310-
1 Adaptor Kit
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POWER MIG 255
Section D-1 Section D-1
TABLE OF CONTENTS
- MAINTENANCE SECTION -
Maintenance ...........................................................................................................Section D
Safety Precautions ........................................................................................................D-2
Routine and Periodic Maintenance ...............................................................................D-2
Drive Rolls and Guide Tubes.........................................................................................D-2
Cable Cleaning ..............................................................................................................D-2
Gun Tubes and Nozzles ................................................................................................D-2
Contact Tip and Gas Nozzle Installation.......................................................................D-4
Liner Removal and Replacement ..................................................................................D-4
Liner Removal, Installation, and Trimming Instructions for Magnum 250L ..................D-4
Gun Handle Disassembly ..............................................................................................D-5
Accessories and Expendable Replacement Parts for Magnum 250L Gun and Cable Assemblies
............D-6
POWER MIG 255
MAINTENANCE
D-2 D-2
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SAFETY PRECAUTIONS
•Have a qualified electrician do the maintenance
and troubleshooting work.
•Disconnect the input power off using the dis-
connect switch at the main input supply before
working inside machine.
•Unplug the power cable if it is connected to a
receptacle.
------------------------------------------------------------------------
Read the Safety Precautions in the front of this manu-
al before working on this machine.
ROUTINE AND PERIODIC
MAINTENANCE
1. Disconnect input AC power supply lines to the
machine before performing periodic maintenance,
tightening, cleaning, or replacing parts.
Perform the following daily:
1. Check that no combustible materials are in the
welding or cutting area or around the machine.
2. Remove any debris, dust, dirt, or materials that
could block the air flow to the machine.
3. Inspect the electrode cables for any slits, punc-
tures in the cable jacket, or any condition that
would affect the proper operation of the machine.
Perform Periodically:
Clean the inside of the machine with low pressure air
stream. Clean the following parts. Refer to Figure D.1.
Main transformer and output choke.
Power enhancement choke.
Wire drive assembly.
Capacitor bank.
SCR rectifier bridge and heat sink fins.
Fan motor assembly.
Control printed circuit board.
Snubber printed circuit board.
NOTE: The fan motor has sealed bearings which
require no maintenance.
WARNING
DRIVE ROLLS AND GUIDE TUBES
After every coil of wire, inspect the wire drive mecha-
nism. Clean it as necessary by blowing with low pres-
sure compressed air. Do not use solvents for cleaning
the idle roll because it may wash the lubricant out of
the bearing. All drive rolls are stamped with the wire
sizes they will feed. If a wire size other than that
stamped on the roll is used, the drive roll must be
changed.
CABLE CLEANING
Clean the cable liner after using approximately 300
pounds (136 kg) of electrode.
1. Remove the cable from the wire feeder and lay it
out straight on the floor.
2. Remove the contact tip from the gun.
3. With an air hose at the gas diffuser end, use low
pressure to gently blow out the cable liner.
Excessive pressure at the start may cause the dirt to
form a plug.
------------------------------------------------------------------------
4. Flex the cable over its entire length and again blow
out the cable.
5. Repeat this procedure until no more dirt comes
out.
GUN TUBES AND NOZZLES
1. Replace worn contact tips as required.
2. Remove spatter from the inside of the gas nozzle
and tip every 10 minutes of arc time or as required.
CAUTION
POWER MIG 255
MAINTENANCE
D-3 D-3
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FIGURE D.1 — COMPONENT LOCATIONS.
CONTROL PC
BOARD
POWER
ENHANCEMENT
CHOKE
OUTPUT
CHOKE
MAIN
TRANSFORMER
SCR
RECTIFIER
BRIDGE
CAPACITOR
BANK
SNUBBER
PC BOARD
WIRE DRIVE
ASSEMBLY
FAN
MOTOR
ASSEMBLY
POWER MIG 255
MAINTENANCE
D-4 D-4
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CONTACT TIP AND GAS
NOZZLE INSTALLATION
1. Choose the correct size contact tip for the elec-
trode being used (wire size is stenciled on the side
of the contact tip) and screw it snugly into the gas
diffuser.
a. Be sure the nozzle insulator is fully screwed
onto the gun tube and does not block the gas
holes in the diffuser.
2. Slip or screw the appropriate gas nozzle onto the
nozzle insulator.
NOTE: Either a standard 0.50 in. (12.7 mm) or option-
al 0.62 in. (15.9 mm) I.D. slip-on gas nozzle may be
used and should be selected based on the welding
application.
3. Adjust the gas nozzle as appropriate for the
GMAW process to be used.
a. Typically, the contact tip end should be flush
to extended 0.12 in. (3.2 mm) for the short-
circuiting transfer process and recessed 0.12
in. (3.2 mm) for spray transfer.
LINER REMOVAL AND
REPLACEMENT
NOTE: When you change wire size, a replacement
gas diffuser is required. Use the table below to select
the proper diffuser so the liner is held securely in place.
LINER REMOVAL, INSTALLATION,
AND TRIMMING INSTRUCTIONS
FOR MAGNUM 250L
NOTE: The variation in cable lengths prevents the
interchangeability of liners between guns. Once a liner
has been cut for a particular gun, it should not be
installed in another gun unless it can meet the liner cut
off length requirement. Liners are shipped with the
jacket of the liner extended the proper amount.
1. Remove the gas nozzle and nozzle insulator. See
Figure D.2.
2. Locate the set screw in the gas diffuser which is
used to hold the old liner in place.
3. Loosen the set screw with a 5/64 in. (2.0 mm) Allen
wrench.
4. Remove the gas diffuser from the gun tube.
5. Lay the gun and cable out straight on a flat surface.
6. Loosen the set screw located in the brass cable
connector at the feeder end of the cable and pull
the liner out of the cable.
7. Insert a new untrimmed liner into the connector
end of the cable.
a. Check the liner bushing stencil to make sure
it is the appropriate one for the wire size being
used.
8. Fully seat the liner bushing into the connector.
Diameter of
Electrodes Used
0.025-0.030 in. Steel
(0.6-0.8 mm)
0.035-0.045 in. Steel
(0.9-1.2 mm)
3/64 in. Aluminum
(1.2 mm)
Replacement
Liner
Part Number
KP1934-2
KP1934-1
KP1955-1
Size Stenciled on
End of Liner
Bushing
0.030 in. (0.8 mm)
0.045 in. (1.2 mm)
3/64 in. (1.2 mm)
Fixed Nozzle Gas
Diffuser Part No.
(and Stencil)
KP2026-3
KP2026-3
KP2026-3
Adjustable Nozzle
Gas Diffuser Part
No. (and Stencil)
KP2026-2
KP2026-1B1
KP2026-1B1
POWER MIG 255
MAINTENANCE
D-5 D-5
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GUN HANDLE DISASSEMBLY
The internal parts of the gun handle may be inspected
or serviced if necessary.
The gun handle consists of two halves that are held
together with a collar on each end.
To open up the handle:
1. Turn the collars approximately 60 degrees coun-
terclockwise (the same direction as removing a
right hand thread) until the collar reaches a stop.
2. Pull the collar off the gun handle.
NOTE: If the collars are difficult to turn, position the
gun handle against a corner, place a screwdriver
against the tab on the collar and give the screwdriver a
sharp blow to turn the collar past an internal locking rib.
See Figure D.3.
FIGURE D.3 — GUN HANDLE DISASSEMBLY.
9. Tighten the setscrew on the brass cable
connector.
NOTE: Do not install the gas diffuser onto the end of
the gun tube at this time.
10. Straighten the cable with the gas nozzle and noz-
zle insulator removed from the gun tube.
11.Trim the liner to the length shown in Figure D.2.
FIGURE D.2 — LINER MAINTENANCE.
12. Remove any burrs from the end of the liner.
13. Screw the gas diffuser onto the end of the gun tube
and tighten.
NOTE: Be sure the gas diffuser is correct for the liner
being used. (See table and diffuser stencil.)
14. Slightly tighten the set screw in the side of the gas
diffuser against the cable liner using 5/64 in.
(2.0 mm) Allen wrench.
This screw should only be gently tightened. Over tight-
ening will split or collapse the liner and cause poor wire
feeding.
------------------------------------------------------------------------
CAUTION
POWER MIG 255
MAINTENANCE
D-6 D-6
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ACCESSORIES AND EXPENDABLE REPLACEMENT PARTS FOR
MAGNUM 250L GUN AND CABLE ASSEMBLIES
*Included with Power MIG 255.
**Requires S19418-1 Gas Diffuser Assembly.
METRIC SIZE
0.6 - 0.8 mm
0.9 - 1.2 mm
1.2 mm (Alum. Wire)
0.6 mm
0.8 mm
0.9 mm
1.2 mm
0.9 mm
1.2 mm
0.6 mm
0.8 mm
0.9 mm
1.2 mm
1.2 mm (Alum. Wire)
9.5 mm
12.1 mm
15.9 mm
9.5 mm
15.9 mm
15.9 mm
0.6-1.2 mm
12.7 mm
15.9 mm
0.6-0.8 mm
0.9-1.2 mm
ENGLISH SIZE
0.025-0.030 in.
0.035-0.045 in.
3/64 in. (Alum. Wire)
0.025 in.
0.030 in.
0.035 in.
0.045 in.
0.035 in.
0.045 in.
0.025 in.
0.030 in.
0.035 in.
0.045 in.
3/64 in. (Alum. wire)
3/8 in.
1/2 in.
5/8 in.
3/8 in.
5/8 in.
5/8 in.
0.025-0.045 in.
1/2 in.
5/8 in.
0.25-0.030 in.
0.35-0.045 in.
PART NO.
KP1934-2
KP1934-1
KP1955-1
KP2020-6B1
KP2020-7B1
KP2020-1B1*
KP2020-2B1*
KP2021-1B1
KP2021-2B1
KP2021-5B1
KP2021-6B1
KP2022-1B1
KP2022-2B1
KP2010-5B1
KP1931-1
KP1931-2*
KP1931-3
KP1930-1
KP1930-2
KP1930-3
KP2026-3*
KP1935-2
KP1935-1
KP2025-1
KP2026-2
KP2026-1
KP1947-1**
KP2015-1*
KP2041-1
DESCRIPTION
Cable Liner
For 15 ft (4.5 m) or Shorter Cable
Contact Tips
Standard Duty
Heavy Duty
Tapered
Tab (For Aluminum)
Gas Nozzles
Fixed (Flush)
(Recessed)
(Requires: Gas Diffuser Assembly)
Adjustable Slip-On
(Requires: Nozzle Insulator Assembly)
(Requires: Gas Diffuser Assembly)
Gasless Nozzle (for Innershield®)
Gun Tube Assembly
Standard (60 Degrees)
45 Degrees
TABLE D.2
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POWER MIG 255
Section E-1 Section E-1
Theory of Operation ...............................................................................................Section E
Input Line Voltage and Main Transformer.....................................................................E-2
Output Rectification and Feedback Control.................................................................E-3
Constant Voltage Output ..............................................................................................E-4
Wire Drive Motor and Feedback...................................................................................E-5
Thermal and Overload Protection.................................................................................E-6
Overcurrent Protection ...........................................................................................E-6
Wire Feed Overload Protection ..............................................................................E-6
SCR Operation..............................................................................................................E-7
TABLE OF CONTENTS
- THEORY OF OPERATION SECTION -
FIGURE E.1 – BLOCK LOGIC DIAGRAM
LINE
SWITCH
RECONNECT MAIN
TRANSFORMER
SNUBBER
BOARD
RECTIFIER
DIODE
BRIDGE
ARC
VOLTAGE
WIRE
SPEED
GAS
SOLENOID FAN
MOTOR
CONTROL
BOARD
WIRE
DRIVE
MOTOR
TACH
GUN TRIGGER
FEEDBACK
115 VAC
30 VAC
G
A
T
E
S
I
G
N
A
L
SCR
RECTIFIER
POWER
ENHANCEMENT
CHOKE
OUTPUT
CHOKE
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
KNEGATIVE
TERMINAL
POSITIVE
TERMINAL
SHUNT
POWER MIG 255
THEORY OF OPERATION
E-2 E-2
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INPUT LINE VOLTAGE
AND MAIN TRANSFORMER
The desired single phase input power is connected to
the POWER MIG 255 through a line switch located on
the front panel.
Areconnect panel allows the user to configure the
machine for the desired input voltage. This AC input
voltage is applied to the primary of the main trans-
former. The main transformer converts the high
voltage, low current input power to a low voltage, high
current output. In addition, the main transformer also
has an isolated center tapped 30 VAC auxiliary winding
that supplies power to the Control Board for the SCR
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
FIGURE E.2 — INPUT LINE VOLTAGE AND MAIN TRANSFORMER.
LINE
SWITCH
RECONNECT MAIN
TRANSFORMER
SNUBBER
BOARD
RECTIFIER
DIODE
BRIDGE
ARC
VOLTAGE
WIRE
SPEED
GAS
SOLENOID FAN
MOTOR
CONTROL
BOARD
WIRE
DRIVE
MOTOR
TACH
GUN TRIGGER
FEEDBACK
115 VAC
30 VAC
G
A
T
E
S
I
G
N
A
L
SCR
RECTIFIER
POWER
ENHANCEMENT
CHOKE
OUTPUT
CHOKE
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
KNEGATIVE
TERMINAL
POSITIVE
TERMINAL
SHUNT
gate drive circuitry. The weld power windings connect
to the main SCR Rectifier and via the Snubber Board
to the Rectifier Diode Bridge. This AC voltage is recti-
fied and then regulated by the control board. The
resultant +15 VDC and +5 VDC voltages supply power
to the control board circuitry. The 115 VAC winding (X8
and X9) supplies power, through the control board, to
the thermostatically controlled fan motor.
The fan is designed to come on automatically when
weld arc is established. The fan will stay on for a mini-
mum of six minutes after the weld arc is terminated.
The fan will also stay on when the machine’s welding
and feeding are disabled during thermostatic over-tem-
perature protection. (See Thermal and Overload
Protection.)
POWER MIG 255
THEORY OF OPERATION
E-3 E-3
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OUTPUT RECTIFICATION AND
FEEDBACK CONTROL
The AC output from the main transformer secondary
weld winding is rectified and controlled through the
SCR rectifier assembly. Output voltage and current are
sensed at the shunt and output terminals and are fed
back to the control board. The control board compares
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
LINE
SWITCH
RECONNECT MAIN
TRANSFORMER
SNUBBER
BOARD
RECTIFIER
DIODE
BRIDGE
ARC
VOLTAGE
WIRE
SPEED
GAS
SOLENOID FAN
MOTOR
CONTROL
BOARD
WIRE
DRIVE
MOTOR
TACH
GUN TRIGGER
FEEDBACK
115 VAC
30 VAC
G
A
T
E
S
I
G
N
A
L
SCR
RECTIFIER
POWER
ENHANCEMENT
CHOKE
OUTPUT
CHOKE
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
KNEGATIVE
TERMINAL
POSITIVE
TERMINAL
SHUNT
FIGURE E.3 — OUTPUT RECTIFICATION AND FEEDBACK.
the commands of the ARC Voltage Control poten-
tiometer with the feedback signals. The appropriate
gate firing pulses are generated by the control board
and applied to the SCR rectifier assembly. The control
board controls the firing of the SCRs, thus controlling
the output of the machine. See SCR Operation. The
control board also powers and commands the gas
solenoid, fan motor, and the wire drive motor.
POWER MIG 255
THEORY OF OPERATION
E-4 E-4
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CONSTANT VOLTAGE OUTPUT
The controlled DC output from the SCR rectifier
assembly is supplied to the power factor enhancement
choke which limits the rate at which the supply current
rises through the capacitors. The DC output from the
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
FIGURE E.4 — CONSTANT VOLTAGE OUTPUT.
LINE
SWITCH
RECONNECT MAIN
TRANSFORMER
SNUBBER
BOARD
RECTIFIER
DIODE
BRIDGE
ARC
VOLTAGE
WIRE
SPEED
GAS
SOLENOID FAN
MOTOR
CONTROL
BOARD
WIRE
DRIVE
MOTOR
TACH
GUN TRIGGER
FEEDBACK
115 VAC
30 VAC
G
A
T
E
S
I
G
N
A
L
SCR
RECTIFIER
POWER
ENHANCEMENT
CHOKE
OUTPUT
CHOKE
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
KNEGATIVE
TERMINAL
POSITIVE
TERMINAL
SHUNT
power factor enhancement choke is filtered by the
capacitor bank resulting in a constant voltage DC out-
put. Since the output choke is in series with the posi-
tive leg of the rectifier and also in series with the gun
and welding load, a filtered constant voltage output is
applied to the output terminals of the machine.
POWER MIG 255
THEORY OF OPERATION
E-5 E-5
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WIRE DRIVE MOTOR
AND FEEDBACK
The wire drive motor is controlled by the control board.
Amotor speed feedback signal is generated at the
motor tach and sent to the control board. The control
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
FIGURE E.5 — WIRE DRIVE MOTOR AND FEEDBACK.
LINE
SWITCH
RECONNECT MAIN
TRANSFORMER
SNUBBER
BOARD
RECTIFIER
DIODE
BRIDGE
ARC
VOLTAGE
WIRE
SPEED
GAS
SOLENOID FAN
MOTOR
CONTROL
BOARD
WIRE
DRIVE
MOTOR
TACH
GUN TRIGGER
FEEDBACK
115 VAC
30 VAC
G
A
T
E
S
I
G
N
A
L
SCR
RECTIFIER
POWER
ENHANCEMENT
CHOKE
OUTPUT
CHOKE
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
KNEGATIVE
TERMINAL
POSITIVE
TERMINAL
SHUNT
board compares this feedback signal with the com-
mands set forth by the Wire Speed Control poten-
tiometer and sends the appropriate armature voltage to
the wire drive motor. The drive motor speed is thus
controlled which in turn regulates the electrode wire
feed speed through the gun.
POWER MIG 255
THEORY OF OPERATION
E-6 E-6
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THERMAL AND OVERLOAD
PROTECTION
The POWER MIG 255 has built-in protective ther-
mostats that respond to excessive temperatures. One
is located on the output choke. The other thermostat is
located on the SCR heat sink assembly. They open the
wire feed and welder output circuits if the machine
exceeds the maximum safe operating temperature.
This can be caused by a frequent overload, or high
ambient temperature.
The thermostats are self-resetting once the machine
cools sufficiently. If the thermostat shutdown is caused
by excessive output or duty cycle and the fan is oper-
ating normally, the power switch may be left on and the
reset should occur within a 15 minute period. If the fan
is not turning or the air intake louvers are obstructed,
then the input power must be removed and the fan
problem or air obstruction be corrected.
OVERCURRENT PROTECTION
The machine will automatically reduce the output if the
load on the machine exceeds 300 to 320 amperes.
This protects the welding power SCR’s from excessive
short circuit currents and from exceeding their temper-
ature rating before the thermostats can react.
WIRE FEED OVERLOAD PROTECTION
The POWER MIG has solid state overload protection
of the wire drive motor. If the motor becomes over-
loaded, the protection circuitry turns off the wire feed
speed and gas solenoid. Check for proper size tip liner,
and drive rolls, for any obstructions or bends in the gun
cable, and any other factors that would impede the wire
feeding. To resume welding, simply pull the trigger.
There is no circuit breaker to reset, as the protection is
done with reliable solid state electronics.
POWER MIG 255
THEORY OF OPERATION
E-7 E-7
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SCR OPERATION
Asilicon 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. See Figure E.6
for a graphical representation of SCR operation. 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.
When an AC supply voltage is applied to the SCR, the
device spends a certain portion of the AC cycle time in
the off state and the remainder of the time in the on
state. The amount of time spent in the ON state is con-
trolled by the gate.
An SCR is fired by a short burst of current into the gate.
This gate pulse must be more positive than the cath-
ode voltage. Since there is a standard PN junction
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 voltage 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 greater SCR
output. If the gate firing occurs later in the cycle the
conduction time is less resulting in lower SCR output.
FIGURE E.6 — SCR OPERATION.
INPUT
OUTPUT
CATHODE
ANODE
GATE
NOTE: AS THE GATE
PULSE IS APPLIED
LATER IN THE CYCLE
THE SCR OUTPUT
IS DECREASED.
POWER MIG 255
NOTES
E-8 E-8
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POWER MIG 255
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
Main Transformer Test ..........................................................................................F-11
Rectifier Diode Bridge Test...................................................................................F-15
Static SCR Rectifier Assembly Test .....................................................................F-19
Active SCR Rectifier Assembly Test.....................................................................F-23
Wire Drive Motor and Tachometer Feedback Test...............................................F-27
Oscilloscope Waveforms
Normal Open Circuit Voltage Waveform ..............................................................F-31
Typical Output Voltage Waveform - Machine Loaded..........................................F-32
Abnormal Output Voltage Waveform - Machine Loaded One Output SCR Not Functioning .............
F-33
Abnormal Open Circuit Voltage Output Capacitor Bank Not Functioning...........F-34
Typical SCR Gate Voltage Waveform ...................................................................F-35
Replacement Procedures
Control PC Board Removal and Replacement.....................................................F-37
Wire Drive Assembly Removal and Replacement................................................F-41
SCR Output Rectifier Removal and Replacement ...............................................F-45
Capacitor Bank Removal and Replacement ........................................................F-49
Main Transformer and Output Choke Removal and Replacement ......................F-51
Fan Motor and Fan Removal and Replacement ..................................................F-55
Retest After Repair......................................................................................................F-57
HOW TO USE TROUBLESHOOTING GUIDE
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.
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POWER MIG 255
TROUBLESHOOTING & REPAIR
F-2 F-2
CAUTION
This Troubleshooting Guide is provided to help
you locate and repair possible machine
malfunctions. Simply follow the three-step
procedure listed below.
Step 1. LOCATE PROBLEM (SYMPTOM). Look
under the column labeled “PROBLEM
(SYMPTOMS)”. This column describes possible
symptoms that the machine may exhibit. Find
the listing that best describes the symptom that
the machine is exhibiting. Symptoms are
grouped into three main categories: Feeding
Problems and Welding Problems.
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
conducted without removing the case
wrap-around cover.
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.
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
electrical wiring diagrams and schematics. Refer
to the Electrical Diagrams Section Table of
Contents to locate the appropriate diagram.
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
1-888-935-3877.
POWER MIG 255
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TROUBLESHOOTING & REPAIR
F-3 F-3
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:
1. Determine to the best of your technical ability
that the PC board is the most likely component
causing the failure symptom.
2. Check for loose connections at the PC board
to assure that the PC board is properly
connected.
3. If the problem persists, replace the suspect PC
board using standard practices to avoid static
electrical damage and electrical shock. Read
the warning inside the static resistant bag and
perform the following procedures:
PC board can be damaged by static electricity.
- Remove your body’s static
charge before opening the static-
shielding bag. Wear an anti-static
wrist strap. For safety, use a 1
Meg ohm resistive cord connected
to a grounded part of the
equipment frame.
- If you don’t have a wrist strap,
touch an un-painted, grounded,
part of the equipment frame. Keep
touching the frame to prevent
static build-up. Be sure not to
touch any electrically live parts at
the same time.
- Tools which come in contact with the PC board must
be either conductive, anti-static or static-dissipative.
ELECTRIC SHOCK
can kill.
•Have an electrician install and
service this equipment. Turn the
input power OFF at the fuse box
before working on equipment. Do
not touch electrically hot parts.
- Remove the PC board from the static-shielding bag
and place it directly into the equipment. 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 static-shield-
ing bag.
- 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-shielding
bag. This will prevent further damage and allow prop-
er failure analysis.
4. Test the machine to determine if the failure
symptom has been corrected by the
replacement PC board.
NOTE:It is desirable to have a spare (known good)
PC board available for PC board troubleshooting.
NOTE:Allow the machine to heat up so that all
electrical components can reach their operating
temperature.
5. Remove the replacement PC board and
substitute it with the original PC board to
recreate the original problem.
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 terminal strips.
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.
6. Always indicate that this procedure was
followed when warranty reports are to be
submitted.
NOTE:Following this procedure and writing on the
warranty report, “INSTALLED AND SWITCHED PC
BOARDS TO VERIFY PROBLEM,” will help avoid
denial of legitimate PC board warranty claims.
PC BOARD TROUBLESHOOTING PROCEDURES
ATTENTION
Static-Sensitive
Devices
Handle only at
Static-Safe
Workstations
WARNING
CAUTION
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TROUBLESHOOTING & REPAIR
F-4 F-4
POWER MIG 255
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
1-888-935-3877.
TROUBLESHOOTING GUIDE Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS) POSSIBLE AREAS OF
MISADJUSTMENT(S) RECOMMENDED
COURSE OF ACTION
Major Physical or Electrical Damage
is Evident
Machine is dead — no open circuit
voltage output and no wire feed
when gun trigger is pulled. The
machine display may be lit.
1. Contact your local Lincoln
Electric Authorized Field Service
Facility.
1. Make certain that the input
power switch is in the "ON" posi-
tion.
2. Check the input voltage at the
machine. Input voltage must
match the rating plate and the
reconnect panel.
3. Blown or missing fuses in the
input line.
4. The thermostats may be open
due to machine overheating. If
machine operates normally after
a cooling off period then check
for proper fan operation and
ventilation. Make certain that the
machine's duty cycle is not
being exceeded.
5. Check the trigger circuit. Leads
#324 to #325 should have conti-
nuity (zero ohms) when the gun
trigger is pulled. If not then the
gun may be faulty — replace.
6. Make sure unit is not connected
to a portable generator.
1. Contact The Lincoln Electric
Service Dept. 1-888-935-3877
1. Check input power switch (S1).
It may be faulty.
2. Check for lose or broken wires
at the reconnect panel.
3. Perform Main Transformer
Test.
4. Perform Rectifier Diode Bridge
Test.
5. Check the thermostats and
associated leads for loose or
broken connections. See wiring
diagram.
6. The control board may be faulty.
Replace.
OUTPUT PROBLEMS
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TROUBLESHOOTING & REPAIR
F-5 F-5
TROUBLESHOOTING GUIDE Observe Safety Guidelines
detailed in the beginning of this manual.
POWER MIG 255
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
1-888-935-3877.
PROBLEMS
(SYMPTOMS) POSSIBLE AREAS OF
MISADJUSTMENT(S) RECOMMENDED
COURSE OF ACTION
No open circuit voltage output but
wire feeds normally when gun trig-
ger is pulled.
Wire feeds but welding output is low
causing wire to “stub”. Welds are
“cold”. Machine cannot obtain full
rated output of 200 amps at 28 volts.
1. Check the input voltage at the
machine. Input voltage must
match the rating plate and the
reconnect panel.
2. The gun may be faulty. Check
or replace.
1. Make sure that the proper wire
and procedures are being used.
2. Check gun and work cable for
loose or faulty connections.
1. Check for loose or broken con-
nections at the output terminals,
the chokes, the capacitor bank
and all heavy current carrying
leads. See Wiring Diagram.
2. Make sure that the transformer
secondary leads are securely
connected to the SCR rectifier
assembly.
3. Perform the SCR Rectifier
Assembly Tests.
4. Perform Main Transformer
Test.
5. The control board may be faulty.
Replace.
1. Check for loose or faulty con-
nections of the heavy current
carrying leads.
2. The output capacitor bank may
be faulty. Check for loose con-
nections at the capacitors. Also
check for leaky capacitors.
Replace if necessary.
WARNING: The liquid elec-
trolyte in these capacitors is
toxic. Avoid contact with any
portion of your body.
3. Perform the SCR Rectifier
Assembly Tests.
4. Perform the Main Transformer
Test.
5. The control board may be faulty.
Replace.
OUTPUT PROBLEMS (Continued)
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-6 F-6
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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
1-888-935-3877.
TROUBLESHOOTING GUIDE Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS) POSSIBLE AREAS OF
MISADJUSTMENT(S) RECOMMENDED
COURSE OF ACTION
The output voltage and wire feed is
present continuously or pulsing
when gun trigger is NOT activated.
The output voltage is present contin-
uously when gun trigger is NOT acti-
vated.
1. Remove the gun. If the problem
is resolved the gun trigger circuit
is faulty. Repair or replace.
2. If problem persists when gun
assembly is removed from
machine, then the problem is
within the POWER MIG 255.
Contact your local Lincoln Electric
Authorized Field Service Facility.
1. Check the machine's internal
trigger leads for grounds or
shorts. See Wiring Diagram.
2. The control board may be faulty.
Replace.
1. Perform the SCR Rectifier
Assembly Tests.
2. The control board may be faulty.
Replace.
OUTPUT PROBLEMS (Continued)
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-7 F-7
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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
1-888-935-3877.
TROUBLESHOOTING GUIDE Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS) POSSIBLE AREAS OF
MISADJUSTMENT(S) RECOMMENDED
COURSE OF ACTION
No control of arc voltage. Wire feed-
ing is normal.
There is no gas flow when gun trig-
ger is pulled. Wire feeds and weld
voltage is present.
The machine stops feeding wire
while welding.
1. The arc voltage control poten-
tiometer may be dirty. Rotate
several times and check if prob-
lem is resolved.
1. Check gas source and hoses for
leaks or kinks.
1. Check for adequate wire supply.
2. Check for mechanical restric-
tions in the wire feeding path.
The gun may be clogged.
3. Check gun liner and tip are cor-
rect for wire size being used.
4. Check spindle for ease of rota-
tion.
5. If Timer Option Kit is installed,
make sure spot timer knob is set
to OFF.
1. The arc voltage control poten-
tiometer may be faulty. Check or
replace. See Wiring Diagram.
2. Perform the SCR Rectifier
Assembly Tests.
3. The control board may be faulty.
Replace.
1. Check the gas solenoid by dis-
connecting it from the control
board (Plug J8) and applying a
12 VDC external supply to the
gas solenoid. If the solenoid
does NOT activate then it may
be faulty. Replace.
2. The control broad may be faulty.
Replace.
1. Check the motor armature cur-
rent. Normal armature current is
2.0 to 2.7 amps maximum. If
the motor armature current is
normal the control board may be
faulty. Replace.
2. If the motor armature current is
high (over 2.7 amps) and there
are NO restrictions in the wire
feeding path then the motor or
gear box may be defective.
Replace.
FUNCTION PROBLEMS
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-8 F-8
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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
1-888-935-3877.
TROUBLESHOOTING GUIDE Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS) POSSIBLE AREAS OF
MISADJUSTMENT(S) RECOMMENDED
COURSE OF ACTION
No control of wire feed speed. Other
machine functions are normal
There is no wire feed when gun trig-
ger is pulled. Normal open circuit
voltage is present.
1. The wire feed speed control
may be dirty. Rotate several
times and check if problem is
resolved.
1. Check for adequate wire supply.
2. If the drive rolls are turning then
check for a mechanical restric-
tion in the wire feed path.
3. The gun liner may be clogged.
Check or replace.
4. If the drive rolls are NOT turning
when the gun trigger is pulled
then contact your local Lincoln
Electric Authorized Field Service
Facility.
1. The Wire Speed Control poten-
tiometer may be faulty. Check or
replace. See Wiring Diagram.
2. Perform the Wire Drive Motor
and Tachometer Feedback
Test.
3. The control board may be faulty.
Replace.
1. Perform the Wire Drive Motor
and Tachometer Feedback
Test.
2. The Wire Feed Control poten-
tiometer may be faulty. Check or
replace. See Wiring Diagram.
3. The control board may be faulty.
Replace.
WIRE FEEDING PROBLEMS
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-9 F-9
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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
1-888-935-3877.
TROUBLESHOOTING GUIDE Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS) POSSIBLE AREAS OF
MISADJUSTMENT(S) RECOMMENDED
COURSE OF ACTION
The arc is unstable and or “hunting”.
Weld bead is narrow or ropy. May
have porosity with electrode stub-
bing into plate.
1. Check for worn or melted con-
tact tip.
2. Check for loose or faulty con-
nections on the work and elec-
trode cables.
3. Make sure electrode polarity or
welding process being used, is
correct.
4. Check for rusty or dirty wire.
5. Make sure machine settings and
gas are correct for process
being used.
1. Make sure the weld procedure
and electrode polarity is correct
for the process being used.
2. Make sure shielding gas is cor-
rect and flow is proper.
3. Make sure the weld joint is not
“contaminated”.
1. Check for loose connections at
the output terminals, the
chokes, the capacitor bank and
all heavy current carrying leads.
See Wiring Diagram.
2. Make sure that the transformer
secondary leads are securely
connected to the SCR rectifier
assembly.
3. The output capacitor bank may
be faulty. Check for loose con-
nections at the capacitors. Also
check for leaky capacitors.
Replace if necessary.
WARNING: The liquid elec-
trolyte in these capacitors is
toxic. Avoid contact with any
portion of your body.
4. Perform the SCR Rectifier
Assembly Tests.
5. The control board may be faulty.
Replace.
1. The output capacitor bank may
be faulty. Check for loose con-
nections at the capacitors. Also
check for leaky capacitors.
Replace if necessary.
WARNING: The liquid elec-
trolyte in these capacitors is
toxic. Avoid contact with any
portion of your body.
2. The control board may be faulty.
Replace.
WELDING PROBLEMS
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-10 F-10
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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
1-888-935-3877.
TROUBLESHOOTING GUIDE Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS) POSSIBLE AREAS OF
MISADJUSTMENT(S) RECOMMENDED
COURSE OF ACTION
The contact tip seizes in the gas
diffuser.
The welding arc is variable and
sluggish.
The arc striking is poor.
1. The tip being over heated due to
excessive current and/or high
duty cycle welding.
2. A light application of high tem-
perature anti-sieze lubricant
(such as Lincoln E2607
Graphite Grease) may be
applied to the contact tip
threads.
1. Check the welding cable con-
nections for loose or faulty con-
nections.
2. Make sure the wire feed speed,
voltage, and shielding gas are
correct for the process being
used.
1. Check the welding cable con-
nections for loose or faulty con-
nections.
2. Make sure the wire feed speed,
voltage, and shielding gas are
correct for the process being
used.
1. Make sure tip is tight in diffuser.
1. Perform the SCR Rectifier
Assembly Tests.
2. The control board may be faulty.
Replace.
1. The output capacitor bank may
be faulty. Check for loose con-
nections at the capacitors. Also
check for leaky capacitors.
Replace if necessary.
WARNING: The liquid elec-
trolyte in these capacitors is
toxic. Avoid contact with any
portion of your body.
2. The control board may be faulty.
Replace.
WELDING PROBLEMS (Continued)
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 electrical shock, please observe all safety notes and pre-
cautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to per-
form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
POWER MIG 255
F-11 F-11
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WARNING
TROUBLESHOOTING & REPAIR
MAIN TRANSFORMER TEST
TEST DESCRIPTION
This procedure will determine if the correct voltages are being:
a. Applied to the primary windings of the main transformer.
b. Induced on the secondary and auxiliary windings of the main transformer.
MATERIALS NEEDED
Volt/Ohm Meter
3/8 in. Nutdriver
5/16 in. Nutdriver
POWER MIG 255
F-12 F-12
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TROUBLESHOOTING & REPAIR
4. Locate plug J5 and plug J6 on the
G3521 control PC board, and J9 on the
M19248 snubber PC board. See Figure
F.1.
NOTE: The location of plugs may vary
depending on the machine code.
5. Locate the following leads on plug J6
on the G3521 control PC board:
TEST PROCEDURE
The ON/OFF POWER SWITCH will be
“hot” during these tests.
----------------------------------------------------------
NOTE: Secondary voltages will vary pro-
portionately with the primary input voltage.
1. Disconnect the main input power sup-
ply to the machine.
2. Remove the case top and side panels
with a 3/8 in. nutdriver.
3. Remove the tool tray with a 5/16 in. nut-
driver.
FIGURE F.1 — G3521 CONTROL PC BOARD AND M19248 SNUBBER PC BOARD
MAIN TRANSFORMER TEST POINTS.
J6
J5
J3
J8
J1
J4
J2
J9
X8
(16J5)
X9
(8J5)
#206
(3J5)
#208S
(2J9)
#209S
(6J9)
X7
(4J6)
X6
(5J6)
X5
(6J6)
MAIN TRANSFORMER TEST (continued)
WARNING
PLUG
LOCATION
6J6
5J6
4J6
LEAD
X5
X6
X7
POWER MIG 255
F-13 F-13
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TROUBLESHOOTING & REPAIR
11.Turn the machine ON.
12. Make the following voltage tests at plug
J5.
a. Turn the machine OFF between
each test.
b. Carefully insert the meter probes
into the back of each Molex plug
pin cavity to perform the test.
c. If the voltage tested is incorrect,
check for loose or broken leads
between the test points and the
main transformer.
d. If the voltage is not corrected, go to
step 16.
13. Turn OFF the machine power.
6. Connect main input power to the
machine.
7. Turn the POWER MIG 255 ON/OFF
POWER SWITCH to ON.
8. Carefully make the following voltage
tests at plug J6.
a. Turn the machine OFF between
each test.
b. Carefully insert the meter probes
into the back of each Molex plug
pin cavity to perform the test.
9. Turn OFF the machine.
10. Locate the following leads on plug J5
on the G3521 control PC board. See
Figure F.1.
MAIN TRANSFORMER TEST (continued)
FROM
LEAD
X5
(6J6)
X5
(6J6)
X6
(5J6)
TO
LEAD
X6
(5J6)
X7
(4J6)
X7
(4J6)
EXPECTED
VOLTAGE
15VAC
30VAC
15VAC
PLUG
LOCATION
16J5
8J5
LEAD
X8
X9
FROM
LEAD
X8
(16J5)
TO
LEAD
X9
(8J5)
EXPECTED
VOLTAGE
115VAC
POWER MIG 255
TROUBLESHOOTING AND REPAIR
F-14 F-14
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c. If any of the voltages tested are
incorrect, check for loose or broken
leads between the test points and
the main transformer.
d. If ALL the voltages tested are incor-
rect or missing, go to step 16.
17. Test for correct nameplate input
voltage between the H1 lead at the
ON/OFF POWER SWITCH to H2 or
H3 (H5 if connected for 575 VAC) at
the reconnect panel. Voltage tested will
vary depending on input voltage
connection. See wiring diagram for test
point locations.
a. If the voltage test is incorrect,
-check for loose or broken leads
between the reconnect panel and
the ON/OFF POWER SWITCH.
-test the ON/OFF POWER
SWITCH for proper operation.
b. If the correct nameplate voltage is
being applied to the main trans-
former and one or more of the sec-
ondary voltages are missing or are
incorrect, the main transformer may
be faulty. Replace.
14. Locate the following leads on plug J9
on the M19248 snubber PC board and
on plug J5 on the G3521 control PC
board. See Figure F.1.
G3521:
M19248:
15. Turn the machine ON.
16. Make the following voltage tests at plug
J9 on the M19248 snubber PC board
and at plug J5 on the G3521 control PC
board.
a. Turn the machine OFF between
each test.
b. Carefully insert the meter probes
into the back of each Molex plug
pin cavity to perform the test.
MAIN TRANSFORMER TEST (continued)
PLUG
LOCATION
3J5
LEAD
206
PLUG
LOCATION
2J9
6J9
LEAD
208S
209S
FROM
LEAD
208S
(2J9 on
M19248)
208S
(2J9 on
M19248)
209S
(6J9 on
M19248)
TO
LEAD
209S
(6J9 on
M19248)
206
(3J5 on
G3521)
206
(3J5 on
G3521)
EXPECTED
VOLTAGE
56VAC
28VAC
28VAC
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-15 F-15
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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
RECTIFIER DIODE BRIDGE TEST
Service and repair should only be performed by Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in dan-
ger to the technician or machine operator and will invalidate your factory war-
ranty. For your safety and to avoid electrical 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 per-
form the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
TEST DESCRIPTION
This test will determine if the correct voltages are being:
a. Applied to the diode bridge.
b. Supplied from diode bridge to the control PC board.
MATERIALS NEEDED
3/8 in. Nutdriver
Volt-ohmmeter
POWER MIG 255 wiring diagrams (See Electrical Diagrams Section of this Manual)
WARNING
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-16 F-16
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Leads #208R, #209R, and #354 are
connected to the rectifier diode bridge
(D2). See Figure F.2. Lead #206 is
connected at the output shunt. See the
wiring diagram.
5. Connect main input power to the
machine.
TEST PROCEDURE
1. Disconnect the main AC input power to
the machine.
2. Remove the case top and side panels
with a 3/8 in. nutdriver.
3. Perform the Main Transformer Test to
ensure the proper voltages are supplied
to the M19248 snubber PC board.
4. Locate the following leads:
RECTIFIER DIODE BRIDGE TESTING (continued)
LEAD
208R
209R
354
206
FIGURE F.2 — G3521 RECTIFIER DIODE BRIDGE LOCATION.
RECTIFIER
DIODE BRIDGE
(D2)
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-17 F-17
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9. Make the following voltage test:
a. Turn the machine OFF between
each test.
b. Carefully connect the meter probes
to the exposed lead connections.
c. Turn the machine ON to conduct
the voltage test.
10. If the DC voltage tested is incorrect or
missing, and the AC voltages are cor-
rect, the rectifier diode bridge may be
faulty.
6. Turn the POWER MIG 255 ON/OFF
POWER SWITCH to ON.
7. Carefully make the following voltage
tests:
a. Turn the machine OFF between
each test.
b. Carefully connect the meter plugs
to the exposed lead connections.
c. Turn the machine ON to conduct
the voltage test.
8. If any of the AC voltages tested are
incorrect or missing, check the M19248
snubber PC board and associated
leads and connections. See the wiring
diagram.
RECTIFIER DIODE BRIDGE TESTING (continued)
FROM
LEAD
208R
209R
TO
LEAD
206
206
EXPECTED
VOLTAGE
28 VAC
28 VAC
FROM
LEAD
354
TO
LEAD
206
EXPECTED
VOLTAGE
36 VDC
POWER MIG 255
NOTES
F-18 F-18
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POWER MIG 255
TROUBLESHOOTING & REPAIR
F-19 F-19
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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
STATIC SCR RECTIFIER ASSEMBLY TEST
Service and repair should only be performed by Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in dan-
ger to the technician or machine operator and will invalidate your factory war-
ranty. For your safety and to avoid electrical 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 per-
form the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
TEST DESCRIPTION
This test is used to quickly determine if an SCR or diode is shorted or “leaky.” See the
Machine Waveform Section in this manual for normal and abnormal output waveforms.
MATERIALS NEEDED
Analog Volt-ohmmeter
POWER MIG 255 wiring diagrams (See Electrical Diagrams Section of this Manual)
3/8 in. Nutdriver
5/16 in. Nutdriver
1/2 in. Open end or socket wrench
WARNING
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-20 F-20
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4. Verify that the capacitors have
completely discharged with a volt-
ohmmeter.
5. Disconnect plugs J6 from the G3521
control board and J9 from the M19248
snubber PC board. This electrically
isolates the SCR bridge assembly.
See Figure F.3.
TEST PROCEDURE
1. Disconnect main AC input power to the
machine.
2. Remove the case top and side panels
with a 3/8 in. nutdriver.
3. Remove the tool tray with a 5/16 in. nut-
driver.
STATIC SCR RECTIFIER ASSEMBLY TEST (continued)
FIGURE F.3 — REMOVE PLUGS J6 AND J9 TO PERFORM STATIC RECTIFIER ASSEMBLY TEST.
J6
J5
J3
J8
J1
J4
J2
J9
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-21 F-21
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FIGURE F.5 — SCR 1 TEST POINTS.
9. Test for high or infinite resistance from
the cathode to the anode of SCR 1 by
reversing the meter leads. See Figure
F.5.
a. If a high or infinite resistance is indi-
cated for both tests 6 and 7, the
SCR 1 is not “shorted”.
b. If a low resistance is indicated in
either tests 6 or 7, the SCR is faulty.
Replace the SCR assembly.
10. Repeat steps 6 and 7 to test SCR 2.
11. Reconnect leads X2 and X3 (braided
copper strap).
12. Reconnect plugs J9 and J6.
13. If this test did not identify the problem,
or to further test the SCR, go to the
Active SCR Rectifier Assembly Test.
FIGURE F.4 — LOCATION OF
LEADS X2 AND X3.
6. Disconnect leads X2 and X3 (braided
copper strap) from the negative capaci-
tor bank buss bar using a 1/2 in. open
end wrench. See Figure F.4.
7. Separate leads X2 and X3 from the
negative capacitor bank buss bar. Be
sure there is no electrical contact.
NOTE: DO NOT DISASSEMBLE THE SCR
RECTIFIER HEAT SINK ASSEMBLY.
8. Test for high or infinite resistance from
the anode to the cathode of SCR 1
using an analog ohmmeter. See Figure
F.5.
NEGATIVE
CAPACITOR
BANK BUSS
BAR
LEADS X2 AND X3
CONNECTION
STATIC SCR RECTIFIER ASSEMBLY TEST (continued)
POWER MIG 255
NOTES
F-22 F-22
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POWER MIG 255
TROUBLESHOOTING & REPAIR
F-23 F-23
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ACTIVE SCR RECTIFIER ASSEMBLY TEST
Service and repair should only be performed by Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in dan-
ger to the technician or machine operator and will invalidate your factory war-
ranty. For your safety and to avoid electrical 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 per-
form the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
TEST DESCRIPTION
The Active SCR Rectifier Assembly Test will determine if the device is able to be gated
ON and conduct current from anode to cathode.
The Static SCR Rectifier Assembly Test must be performed before proceeding with the
Active SCR Test.
MATERIALS NEEDED
3/8 in. Nutdriver
5/16 in. Nutdriver
An SCR Tester as specified in this procedure
POWER MIG 255 wiring diagrams (See Electrical Diagrams Section of this Manual)
SCR Heat Sink Assembly Drawings
Avolt-ohmmeter
WARNING
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-24 F-24
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4. Verify that the capacitors have
completely discharged with a volt-
ohmmeter.
5. Disconnect plugs J6 from the G3521
control board and J9 from the M19248
snubber PC board. This electrically
isolates the SCR bridge assembly.
See Figure F.6.
TEST PROCEDURE
1. Disconnect main AC input power to the
machine.
2. Remove the case top and side panels
with a 3/8 in. nutdriver.
3. Remove the tool tray with a 5/16 in. nut-
driver.
ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued)
FIGURE F.6 — CONTROL BOARD MOLEX PLUG LOCATIONS FOR G3521 PC CONTROL BOARD.
J6
J5
J3
J8
J1
J4
J2
J9
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-25 F-25
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8. Use a commercial SCR tester or con-
struct the tester circuit shown in Figure
F.8. One 6-volt lantern battery can be
used. R1 and R2 resistor values are
±10%. Set voltmeter scale low, at
approximately 0-5 volts or 5-10 volts.
a. Test the voltage level of the battery.
Short leads (A) and (C). Close
switch SW-1. Battery voltage
should be 4.5 volts or higher. If
lower, replace the battery.
FIGURE F.8 — SCR TESTER CIRCUIT
AND SCR CONNECTIONS.
6. Disconnect leads X2 and X3 (braided
copper strap) from the negative capaci-
tor bank buss bar using a 1/2 in. open
end wrench. See Figure F.7.
FIGURE F.7 — LOCATION OF
LEADS X2 AND X3.
7. Separate leads X2 and X3 from the
negative capacitor bank buss bar. Be
sure there is no electrical contact.
NOTE: DO NOT DISASSEMBLE THE SCR
RECTIFIER HEAT SINK ASSEMBLY.
ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued)
NEGATIVE
CAPACITOR
BANK BUSS
BAR
LEADS X2 AND X3
CONNECTION
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-26 F-26
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15. Reconnect the tester leads. See Figure
F.8.
a. Connect tester lead (A) to the
cathode.
b. Connect tester lead (C) to the
anode.
c. Disconnect test lead (G) from the
gate.
16. Close switch SW-1.
17. Read meter for zero voltage.
a. If the voltage is zero, the SCR is
functioning.
b. If the voltage is higher than zero,
the SCR is shorted.
18. Perform the Active Test Procedure out-
lined in Steps 6-15 for SCR 2.
19. Replace all SCR assemblies that do not
pass the above tests.
20. Reconnect plug J6 onto the control PC
board and J9 to the snubber PC board.
21. Reconnect leads X2 and X3 to the neg-
ative capacitor bank bus bar.
22. Replace the tool tray and case sides.
9. Connect the tester to the SCR 1 as
shown in Figure F.8.
a. Connect tester lead (A) to the
anode.
b. Connect tester lead (C) to the
cathode.
c. Connect tester lead (G) to the gate.
10. Close switch SW-1.
NOTE: Switch SW-2 should be open.
11. Read meter for zero voltage.
a. If the voltage reading is higher than
zero, the SCR is shorted.
12. Close or keep closed switch SW-1.
13. Close switch SW-2 for 2 seconds and
release and read meter.
a. If the voltage is 3 to 6 volts while
the switch is closed and after the
switch is open, the SCR is
functioning.
b. If the voltage is 3 to 6 volts only
when the switch is closed or there
is no voltage when the switch is
closed, the SCR is defective.
NOTE: Be sure battery is functioning prop-
erly. A low battery can affect the results of
the test. Repeat Battery Test Procedure in
Step 6 if needed.
14. Open switch SW-1.
ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued)
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-27 F-27
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WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST
Service and repair should only be performed by Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in dan-
ger to the technician or machine operator and will invalidate your factory war-
ranty. For your safety and to avoid electrical 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 per-
form the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
TEST DESCRIPTION
This test will determine if the wire drive motor and voltage feedback circuit are func-
tioning properly.
MATERIALS NEEDED
5/16 in. Nutdriver
Volt-Ohmmeter
WARNING
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-28 F-28
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3. Locate plug J1 on the G3521 control
PC board. See Figure F.9.
4. Locate the following leads on plug J1:
5. Connect the main power to the
machine.
TEST PROCEDURE
NOTE: POLARITY MUST BE OBSERVED
FOR THESE TESTS.
Test for Correct Wire Drive Motor Armature
Voltage
1. Disconnect main input power to the
machine.
2. Open the side panels and remove the
tool tray using a 5/16 in. nutdriver.
FIGURE F.9 — PLUG J1 LOCATION ON G3521 PC CONTROL BOARD.
J6
J5
J3
J8
J1
J4
J2
#555
(6J1)
W
(2J1)
#206B
(1J1)
#515B
(5J1)
B
(4J1)
WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued)
PLUG
LOCATION
4J1
2J1
LEAD
B
W
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-29 F-29
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2. Locate plug J1 on the G3521 control
PC board. See Figure F.9.
3. Locate the following leads on Plug J1:
4. Connect main input power to the
machine.
5. Make the following voltage tests:
a. Turn the machine OFF between
each test.
b. Carefully insert the meter probes
into the back of each Molex plug
pin cavity.
6. If the 15 VDC is present, check the
leads to the tachometer circuit.
7. If the leads are okay and 15 VDC is
present, the correct voltage is being
received from the control PC board,
continue with the Supply Voltage to
Tachometer Test.
8. If the 15 VDC is not present and the
leads are okay, the control PC board
may be faulty, replace the control PC
board.
6. Make the following voltage tests:
a. Turn the machine OFF between
each test.
b. Carefully insert the meter probes
into the back of each Molex plug
pin cavity to perform the test.
c. Turn the machine ON and pull the
gun trigger to conduct the voltage
test.
7. If the voltage to the wire drive motor
armature is zero, check the wires
between plug J1 and the wire drive
motor. Also check the electrical connec-
tor J12 for proper connection and con-
tact.
8. If all wires and connectors are good and
the voltage to the drive motor armature
is zero, the G3521 control PC board
may be faulty, replace the control PC
board.
9. If the motor is running at high speed
and the armature voltage is high and
uncontrollable, proceed with the
tachometer test.
TEST FOR SUPPLY VOLTAGE
TO TACHOMETER
1. Disconnect the main AC input power to
the machine.
WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued)
FROM
LEAD
B
(4J1)
TO
LEAD
W
(2J1)
EXPECTED
VOLTAGE
3-20 VDC
(varies depend-
ing on wire feed
speed)
FROM
LEAD
515B
(5J1)
TO
LEAD
206B
(1J1)
EXPECTED
VOLTAGE
15 VDC
PLUG
LOCATION
5J1
1J1
LEAD
515B
206B
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-30 F-30
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c. Turn the machine ON and pull the
gun trigger to conduct the voltage
test.
6. If the 1.5 to 3.5 VDC is present, the
tachometer circuit is sending the cor-
rect feedback signal to the Control PC
Board.
7. If the 1.5 to 3.5 VDC is not present or
not correct, the Control PC Board is
not receiving the proper feedback
voltage from the tachometer circuit.
Check the leads from the tachometer
circuit to the control PC board for loose
or broken connections.
8. If the leads are okay, the tachometer
circuit may be faulty, replace the
tachometer circuit.
9. Replace the tool tray.
TEST FOR FEEDBACK VOLTAGE
TO CONTROL BOARD
1. Disconnect the main AC input power to
the machine.
2. Locate plug J1 on the G3521 control
PC board.
3. Locate the following leads on plug J1
(see Figure F.9):
4. Connect main input power to the
machine.
5. Make the following voltage tests:
a. Turn the machine OFF between
each test.
b. Carefully insert the meter probes
into the back of each Molex plug
pin cavity.
WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued)
PLUG
LOCATION
6J1
1J1
LEAD
555
206B
FROM
LEAD
555
(6J1)
TO
LEAD
206B
(1J1)
EXPECTED
VOLTAGE
1.5 to 3.5 VDC
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-31 F-31
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0 VOLTS
20.0 V 2.5 ms
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 represents 2.5 milliseconds in time.
NOTE: Scope probes connected at
machine output terminals: (+) probe to elec-
trode, (-) probe to work.
Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
Horizontal Sweep . . . . . . . . . 2.5 ms/Div
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
Trigger . . . . . . . . . . . . . . . . . . . . Internal
SCOPE SETTINGS
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-32 F-32
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0 VOLTS
20.0 V 5 ms
MACHINE LOADED TO 250 AMPS AT 26 VDC
TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED
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 represents 5 milliseconds in time.
The machine was loaded with a resistance
grid bank.
NOTE: Scope probes connected at machine
output terminals: (+) probe to electrode, (-)
probe to work.
Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
Horizontal Sweep . . . . . . . . . . 5 ms/Div
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
Trigger . . . . . . . . . . . . . . . . . . . . Internal
SCOPE SETTINGS
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-33 F-33
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0 VOLTS
20.0 V 5 ms
MACHINE LOADED TO 220 AMPS AT 22 VDC
ABNORMAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED
ONE OUTPUT SCR NOT FUNCTIONING
This is NOT a typical DC output voltage
waveform. One output SCR is not function-
ing. Note the increased ripple content. One
SCR gate was disconnected to simulate an
open or non-functioning output SCR. Each
vertical division represents 20 volts and
each horizontal division represents 5 mil-
liseconds in time. The machine was loaded
with a resistance grid bank.
NOTE: Scope probes connected at machine
output terminals: (+) probe to electrode, (-)
probe to work.
Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
Horizontal Sweep . . . . . . . . . . 5 ms/Div
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
Trigger . . . . . . . . . . . . . . . . . . . . Internal
SCOPE SETTINGS
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-34 F-34
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0 VOLTS
20.0 V 5 ms
ABNORMAL OPEN CIRCUIT VOLTAGE
OUTPUT CAPACITOR BANK NOT FUNCTIONING
This is NOT the typical DC output voltage
waveform. The output capacitors are not
functioning. Note the lack of “filtering” in the
output waveform. The output capacitor bank
was disconnected. Each vertical division
represents 20 volts and each horizontal divi-
sion represents 5 milliseconds in time.
NOTE: Scope probes connected at machine
output terminals: (+) probe to electrode, (-)
probe to work.
Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
Horizontal Sweep . . . . . . . . . . 5 ms/Div
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
Trigger . . . . . . . . . . . . . . . . . . . . Internal
SCOPE SETTINGS
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-35 F-35
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0 VOLTS
2.00 V 5 ms
TYPICAL SCR GATE VOLTAGE WAVEFORM
This is a typical SCR gate pulse voltage
waveform. The machine was in an open
circuit condition (no load) and operating
properly. Note that each vertical division
represents 2 volts and each horizontal
division represents 5 milliseconds in time.
NOTE: Scope probes connected at Plug J6
on the control board. The (+) probe to lead
G2, and the (-) probe to lead 204.
Volts/Div . . . . . . . . . . . . . . . . . . 2.0 V/Div
Horizontal Sweep . . . . . . . . . . 5 ms/Div
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
Trigger . . . . . . . . . . . . . . . . . . . . Internal
SCOPE SETTINGS
POWER MIG 255
NOTES
F-36 F-36
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POWER MIG 255
F-37 F-37
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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
TROUBLESHOOTING AND REPAIR
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 electrical shock, please observe all safety notes and pre-
cautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to per-
form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
WARNING
CONTROL PC BOARD
REMOVAL AND REPLACEMENT PROCEDURE
DESCRIPTION
This procedure will aid the technician in the removal and replacement of the Control PC
Board.
MATERIALS NEEDED
5/16 in. Nutdriver
Static electricity grounding strap
Printed Circuit Boards can be damaged by static electricity. Follow static handling
guidelines detailed in “PC Board Troubleshooting Procedures” at the beginning of this
chapter.
------------------------------------------------------------------------------------------------------------------
CAUTION
POWER MIG 255
F-38 F-38
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TROUBLESHOOTING AND REPAIR
CONTROL PC BOARD
REMOVAL AND REPLACEMENT PROCEDURE (Continued)
REMOVAL AND REPLACEMENT
PROCEDURE
1. Disconnect main input power the
machine.
2. Open the side panels and remove the
tool tray using a 5/16 in. nutdriver.
3. Disconnect all wiring harness plugs and
Molex plugs connected to the control
board. See Figure F.10.
FIGURE F.10 — WIRING HARNESS
AND MOLEX PLUG LOCATIONS.
J1
J2
J3
J4
J5
J6
J8
POWER MIG 255
F-39 F-39
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TROUBLESHOOTING AND REPAIR
CONTROL PC BOARD
REMOVAL AND REPLACEMENT PROCEDURE (Continued)
7. When re-installing the control PC board
carefully secure board to mounting
standoffs.
8. Install all plug connectors previously
removed from the control PC board.
9. Install the tool tray and close the side
panels.
4. Ensure a static electricity grounding
strap is used before handling the con-
trol PC boards.
5. Carefully remove the control PC board
from the mounting standoffs.
6. Lift the control PC board straight up and
out from the machine.
FIGURE F.11 — CONTROL BOARD MOUNTING.
PC CONTROL
BOARD
TOOL
TRAY
NOTE: TOP COVER SHOWN
REMOVED FOR CLARITY.
MOUNTING
STANDOFF
POWER MIG 255
NOTES
F-40 F-40
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POWER MIG 255
TROUBLESHOOTING & REPAIR
F-41 F-41
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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 electrical shock, please observe all safety notes and pre-
cautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to per-
form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
WARNING
WIRE DRIVE ASSEMBLY
REMOVAL AND REPLACEMENT PROCEDURE
DESCRIPTION
This procedure will aid the technician in the removal and replacement of the Wire Drive
Assembly.
MATERIALS NEEDED
Large slot head screwdriver
5/16 in. Nutdriver
Small slot head screwdriver
3/4 in. Open end wrench
7/16 in. Nutdriver
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-42 F-42
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6. Disconnect the wire connectors J13
and J12 to the motor/gearbox assem-
bly. See Wiring Diagram.
7. Use a 3/4 in. wrench and remove the
flange nut and positive lead from the
wire drive assembly. See Figure F.12.
8. Use pliers to remove the hose clamp
and flex hose from the wire drive
assembly.
9. Remove the outer guide assembly from
the wire drive assembly by loosening
the thumb screws until the outer guide
can be removed.
PROCEDURE
1. Disconnect main input power to the
machine.
2. Remove the wire gun and wire.
3. Lift the wire drive door to gain access to
the wire drive assembly.
4. Lift the tool tray door to allow access to
the tool tray.
5. Use a 5/16 in. nutdriver and remove the
tool tray to gain access to the
motor/gearbox assembly.
FIGURE F.12 — WIRE DRIVE ASSEMBLY REMOVAL FOR CODES 10563 & 10583 REFER TO P344-F.2
FOR EXPLODED VIEW OF WIRE DRIVE FOR CODES 10986 AND 10990 - SIMILAR PROCEDURE
4
3
7
8
14
13 12
11
2
17
18
19
9
10
1
5
6
16
15
WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT (continued)
1. Wire Drive Assembly
2. Motor/Gearbox Assembly
3. Flange Nut
4. Positive Lead
5. Hose Clamp
6. Flex Hose
7. Outer Guide Assembly
8. Thumb Screw
9. Adjustment Arm Assembly
10. Idle Arm
11. Round Head Screw
12. Lock Washer
13. Flat Washer
14. Molded Drive Roll Shaft
Assembly
15. Pan Head Screw
16. Lock Washer
17. Hex Head Cap Screw
18. Lock Washer
19. Flat Washer
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-43 F-43
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15. Grasp the motor/gearbox assembly and
wiggle the motor/gearbox assembly
gently back and forth until it separates
from the wire drive assembly.
16. Use a 7/16 in. nutdriver to remove the
hex head cap screws, lock washers,
and flat washers securing the wire
drive assembly to the wire drive
compartment.
17. Remove the wire drive assembly from
the wire drive compartment.
18. Reassemble the wire drive assembly in
the reverse order.
10. Rotate the adjustment arm assembly
counterclockwise to release the tension
on the idle arm.
11. Swing the idle arm up and away from
the wire drive assembly.
12. Use a screwdriver and remove the
round head screw, lock washer, and flat
washer securing the molded drive roll
shaft assembly to the wire drive assem-
bly.
13. Remove the molded drive roll shaft
assembly and the rest of the outer
guide assembly from the wire drive
assembly.
14. Use a screwdriver and remove the pan
head screws and lock washers secur-
ing the motor/gearbox assembly to the
wire drive assembly.
WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT (continued)
POWER MIG 255
NOTES
F-44 F-44
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POWER MIG 255
TROUBLESHOOTING & REPAIR
F-45 F-45
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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
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 electrical shock, please observe all safety notes and pre-
cautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to per-
form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
WARNING
SCR OUTPUT RECTIFIER
REMOVAL AND REPLACEMENT PROCEDURE
DESCRIPTION
This procedure will aid the technician in the removal and replacement of the SCR
Assembly.
MATERIALS NEEDED
1/2 in. Open end wrench
1/2 in. Socket wrench, universal tool, and extension
3/8 in. Nutdriver
3/8 in. Open end wrench
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-46 F-46
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3. Disconnect lead #204 and heavy alu-
minum choke lead from the middle heat
sink with a 1/2 in. socket wrench and
1/2 in. open end wrench. See Figure
F.14.
4. Remove the diode lead from the nega-
tive capacitor band buss bar on the
right side of the machine using a 1/2 in.
socket and 3/8 in. open end wrench.
FIGURE F.14 — MIDDLE HEAT SINK
LEAD DISCONNECTION.
PROCEDURE
1. Remove the case side panels using a
3/8 in. nutdriver.
2. Disconnect lead #208S and trans-
former lead X1 from the heat sink on
the left side of the machine using a 1/2
in. socket wrench. See Figure F.13.
a. Thin lead is always on the outboard
side of the connection.
FIGURE F.13 — LEFT HEAT SINK
LEAD DISCONNECTION.
SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENT (continued)
LEAD X1
LEAD
#208S
LEFT
HEAT SINK
HEAVY
LEAD LEAD
#204S
MIDDLE
HEAT SINK
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-47 F-47
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8. Clear the leads and carefully remove
the SCR rectifier assembly.
NOTE: When installing the SCR rectifier
assembly, apply a thin coating of Dow
Corning #340 compound to the electrical
connections.
9. Unplug leads 320 and 320B from the
SCR heat sink thermostat on the right
side at the SCR assembly.
10. Reassemble the SCR assembly in the
reverse order.
5. Remove lead #209S and transformer
lead X4 from the right side heat sink
using a 1/2 in. socket wrench and
1/2 in. open end wrench. See Figure
F.15.
6. Unplug the SCR gate leads G1 and G2
(see wire markers and wiring diagram).
7. Remove the four nuts holding the SCR
assembly to the floor of the machine
using a 3/8 in. nutdriver.
FIGURE F.15 — RIGHT HEAT SINK LEAD DISCONNECTION.
LEAD
X4
LEAD
#209S
LEAD
#320B
LEAD
#320
SCR DIODE
LEAD
SCR
ASSEMBLY
SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENT (continued)
POWER MIG 255
NOTES
F-48 F-48
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POWER MIG 255
TROUBLESHOOTING & REPAIR
F-49 F-49
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The liquid electrolite in the capacitors is toxic. Do not touch the capacitors with
any part of your body.
-------------------------------------------------------------------------------------------------------------------
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 electrical shock, please observe all safety notes and pre-
cautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to per-
form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
WARNING
CAPACITOR BANK
REMOVAL AND REPLACEMENT PROCEDURE
DESCRIPTION
This procedure will aid the technician in the removal and replacement of the Capacitor
Bank.
MATERIALS NEEDED
5/16 in. Nutdriver
3/8 in. Nutdriver
1/2 in. Open end wrench
3/8 in. Open end wrench
Wiring diagram
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-50 F-50
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tive capacitor bank buss bar using a
1/2 in. open end wrench.
6. Remove the choke lead and lead 204B
from the positive capacitor bank buss
bar using two 1/2 in. open end wrench-
es.
7. Remove the power factor enhancement
choke lead from the positive capacitor
buss bar using two 1/2 in. open end
wrenches.
8. Remove the three nuts holding the
capacitor bank to the floor of the
machine using a 3/8 in. nut driver.
9. Clear the leads and carefully remove
the capacitor bank assembly from the
machine.
10. Reassemble the capacitor bank in the
reverse order.
PROCEDURE
See Figure F.16 for location of capacitor
bank removal and replacement components.
1. Disconnect main input power to the
machine.
2. Remove the case side panels using a
3/8 in. nutdriver.
3. Test that the capacitors are discharged
using a volt ohmmeter. Polarity must
be observed.
4. Remove the two transformer secondary
leads X2 and X3 (braided copper strap)
from the negative capacitor bank buss
bar using two 1/2 in. open end wrench-
es.
5. Remove the shunt, leads 206, 206B,
and the SCR diode lead from the nega-
FIGURE F.16 — LOCATION OF CAPACITOR BANK REMOVAL AND REPLACEMENT COMPONENTS.
SCR DIODE
LEAD LEAD
#206B
LEAD
#206
SHUNT
CAPACITOR
BANK
OUTPUT
CHOKE LEAD
POWER
ENHANCEMENT
CHOKE LEAD
LEADS
X1 AND X2
CAPACITOR BANK REMOVAL AND REPLACEMENT (continued)
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-51 F-51
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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
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 electrical shock, please observe all safety notes and pre-
cautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to per-
form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
WARNING
MAIN TRANSFORMER AND OUTPUT CHOKE
REMOVAL AND REPLACEMENT PROCEDURE
DESCRIPTION
This procedure will aid the technician in the removal and replacement of the Main
Transformer and Choke Assembly.
MATERIALS NEEDED
5/16 in. Nut Driver
1/2 in. Open end wrench
3/8 in. Open end wrench
1/2 in. Socket wrench, extender, universal adapter
Wire cutters
Phillips head screwdriver
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-52 F-52
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6. Remove the two transformer secondary
leads X2 and X3 (braided copper strap)
from the negative capacitor bank buss
bar using two 1/2 in. open end wrench-
es.
7. Disconnect and label all transformer
leads from the reconnect panel using a
3/8 in. open end wrench.
8. Disconnect and label all leads from the
input power switch.
9. Remove the power switch.
10. Disconnect thermostat leads #320 and
#320B from the SCR Rectifier.
PROCEDURE
1. Disconnect main input power to the
machine.
2. Remove the case side panels using a
3/8 in. nutdriver.
3. Test that the capacitors are discharged
using a volt ohmmeter. Polarity must
be observed.
4. Remove lead X1 from the left side SCR
heat sink assembly using a 1/2 in. sock-
et wrench, extender and universal
adapter. See Figure F.17.
5. Remove lead X4 from the right side
heat sink assembly using a 1/2 in. sock-
et wrench, extender and universal
adapter.
FIGURE F.17 — MAIN TRANSFORMER REMOVAL.
OUTPUT
CHOKE
LEAD
LEAD
X1
LEAD
X4
LEADS
X2 AND X3
POWER
ENHANCEMENT
CHOKE
MAIN
TRANSFORMER
PLUG-IN LEADS ARE
NOT SHOWN FOR
CLARITY.
NOTE:
OUTPUT
CHOKE
POSITIVE
LEAD
MAIN TRANSFORMER AND OUTPUT CHOKE
REMOVAL AND REPLACEMENT (continued)
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-53 F-53
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11. Unplug and label leads X5, X6, X7, X8, and X9.
These leads have connectors near the trans-
former which can be disconnected.
12. Disconnect the output choke lead from the posi-
tive capacitor bank buss using two 1/2 in. open
end wrenches.
13. Remove the other output choke lead from the
positive output terminal using a 1/2 in. wrench.
13. Remove all cable ties, wire mounts, and any har-
ness type that could get in the way during trans-
former removal using wire cutters and screw
driver.
14. Remove the four nuts and washers mounting the
transformer to the floor of the machine using a
1/2 in. wrench.
15. Carefully remove the main transformer and choke
assembly.
16. Reassemble the main transformer and choke
assembly in the reverse order.
MAIN TRANSFORMER AND OUTPUT CHOKE
REMOVAL AND REPLACEMENT (continued)
POWER MIG 255
NOTES
F-54 F-54
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POWER MIG 255
TROUBLESHOOTING & REPAIR
F-55 F-55
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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
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 electrical shock, please observe all safety notes and pre-
cautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to per-
form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
WARNING
FAN MOTOR ASSEMBLY
REMOVAL AND REPLACEMENT PROCEDURE
DESCRIPTION
This procedure will aid the technician in the removal and replacement of the Fan Motor
Assembly.
MATERIALS NEEDED
3/8 in. Nutdriver
11/32 in. Open end wrench
Slot head screwdriver
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-56 F-56
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a. Loosen and remove the two nuts
and lock washers from the motor
mounting bracket using a 11/32 in.
open end wrench.
b. When the motor is free from the
mounting bracket, slide the motor
from the POWER MIG unit.
5. Install the replacement motor in the
reverse order of removal.
6. Install the fan blade and tighten the fan
blade clamp. Ensure the fan is in the
same position on the shaft as it was
prior to removal.
a. Spin the fan to be sure it is free to
rotate.
7. Reassemble the remaining compo-
nents in reverse order of removal.
PROCEDURE
1. Disconnect main input power to the
machine.
1. Remove the case side panels using a
3/8 in. nutdriver.
2. Disconnect the fan motor leads #352
and #352. See Figure F.18.
3. Remove the fan blade. Note the posi-
tion of the fan on the shaft for reassem-
bly.
a. Use a screwdriver to loosen the fan
blade clamp.
b. Slide the fan blade off the motor
shaft.
4. Remove the fan motor.
FIGURE F.18 — FAN MOTOR ASSEMBLY REMOVAL.
LEAD
#352
LEAD
#353
FAN
MOTOR
FAN
BLADE
FAN
BLADE
CLAMP
FAN MOTOR ASSEMBLY REMOVAL AND REPLACEMENT (continued)
POWER MIG 255
TROUBLESHOOTING AND REPAIR
F-57 F-57
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INPUT IDLE AMPS AND WATTS
WIRE SPEED RANGE
OPEN CIRCUIT VOLTAGE
RETEST AFTER REPAIR
Maximum Idle Watts
Maximum Idle Amps
Input Volts/Hertz
4007.0230/60
50 - 700 IPM (1.27 - 17.8 m/minute)
35-40 VDC
POWER MIG 255
NOTES
F-58 F-58
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POWER MIG 255
Section G-1 Section G-1
TABLE OF CONTENTS
- ELECTRICAL DIAGRAMS SECTION -
Electrical Diagrams ...............................................................................................Section G
Wiring Diagram - Entire Machine - Code 10563 - (L10979) . . . . . . . . . . . . . . . . . . . .G-2
Wiring Diagram - Entire Machine - Code 10583 - (L10980) . . . . . . . . . . . . . . . . . . . .G-3
Wiring Diagram - Entire Machine - Code 10986 - (L11980) . . . . . . . . . . . . . . . . . . . .G-4
Wiring Diagram - Entire Machine - Code 10990 - (L11979) . . . . . . . . . . . . . . . . . . . .G-5
Control PC Board Schematic (G3520-1D1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-6
Control PC Board Assembly (G3521-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-7
Display PC Board Schematic (L10951) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-8
Display PC Board Assembly (L10952-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-9
Snubber PC Board Schematic (S24374) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-10
Snubber PC Board Assembly (M19248-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-11
G-2
ELECTRICAL DIAGRAMS
POWER MIG 255
WIRING DIAGRAM - ENTIRE MACHINE - CODE 10563 - (L10979)
392
325
515B
209S
**
204S
209R
209
209S
W
254
256
551
254A
552
COLOR CODE:
ELECTRICAL SYMBOLS PER E1537
GENERAL INFORMATION
POWER MIG 255 (208/230V)
206B
G2
4
5
J7
4
5
6
2
7
8
J11
GUN
TRIGGER
2
325
4
3
4
J12
325
324
H4
H1
9
6
8
7
7
5
4
L1
7
2
1
5
6
265
263
260
261
U - BLUE
R - RED
W - WHITE
B - BLACK
INDICATES CONNECTOR CAVITY NO.
10
3
3
1
2
1
2
253
252
262
267
264
J3
J8
1
J5
J6
1
TO GROUND PER
NATIONAL ELECTRICAL
CODE
OUTPUT
CHOKE
POWER FACTOR
ENHANCEMENT
CHOKE
POWER
TRANSFORMER
2-23-2001A
L10979
B
555
D1
204B
205
352
X9
325B
320
207
FOR SPOOL GUN OPTION
204S
208R
**
208R
P.M.
SECONDARY VOLTAGES SHOWN
ARE NO LOAD RMS VALUES
252
2
3
4
TO
WORK
5
6
MOTOR/
GEARBOX
7
8
9
10
11
14
15
16
6
H3
209
208
206
354
1
2
3
J2
4
5
6
7
8
10
11
12
13
14
2
6
1
2
3
10
CAVITY
WIRE FEED
SPEED
352
1
2
1
B
+
L2
208V
H1
LINE
SWITCH
S1
RECONNECT
PANEL
G
H2
C3C1
X4
205206S
206B
R1
8
1
6
8
9
10
11
12
OUTPUT CHOKE
THERMOSTAT
SCR HEATSINK
ASSEMBLY
THERMOSTAT
116.6V
14.2V
14.2V
28.4V
515B
B
324
206B
L2L1
208
208S
1
2
SCI
325A
543
326
SCI
204
GND
500
C2
+++ C1 THRU C3
31,000 MFD
50V
X7
G1
X6
204
X5
G2
X8
353
207
206S
15 OHMS
100 W
5
4
3
2
1
12
13
2
3
4
5
CONTROL BOARD
CONDUCTOR STRAP AND WORK STUD.
OFF AND REVERSE LEAD CONNECTIONS AT CABLE
"POSITIVE". TO CHANGE POLARITY, TURN THE UNIT
FUTURE APPLICATIONS.
8
7
6
5
4
3
B
-
W
555
354
D2
BAFFLE
MOUNTED
RECTIFIER
DIODE
BRIDGE
R.F.
CHOKE
AS’BLY
B
+
-
325B
541A
320B
320
253256
550
**
DISPLAY
BOARD
5
1
4
1
3
1
4
12
7
8
6
1 1
7
1
1
J10
209R
324
**
J10
GAS
SOLENOID
9
251
353
515B
390
555
206B
B
392
NOTES:
N.A. WELDING CABLE MUST BE OF PROPER CAPACITY FOR THE
CURRENT AND DUTY CYCLE OF IMMEDIATE AND
N.B. THIS DIAGRAM SHOWS THE "ELECTRODE" POLARITY
1J1 J4
J6
J8 J9 J7
(NON-LEAD SIDE OF CONNECTOR)
2
J11
J12 J13
10 34
J2 J5
9
14
816
1
1
2
33
4
X8
X9
X5 X5
X6
R.F. FILTER
X6
X7 X7
X1
2
1
ARC
VOLTAGE
FAN
MOTOR
R3
GND
500
515
550
551
552
J3
CAVITY NUMBERING SEQUENCE
(COMPONENT SIDE OF P.C. BOARD)
2
10
6
8
5
6
NUMBERING SEQUENCE
X9
251254
R4
206
J1
J4
1
3
4
8
7
9
FOR TIMER
OPTION
515
390
206A
515
SCR 1
J13
SCR HEATSINK
ASBLY
SCR 2
X8
230V
TO SINGLE PHASE
SUPPLY LINE
H1
X2
X3
H2
28.4V
W
SNUBBER
BOARD
J9
W
H4H3
W
208S
G1
R
T
A
C
H
U
G-2
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.
G-3
ELECTRICAL DIAGRAMS
POWER MIG 255
WIRING DIAGRAM - ENTIRE MACHINE - CODE 10583 - (L10980)
G-3
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1
209
555
B
W
515
254
262
207
P.M.
208S
J9
B
T
A
C
H
D1
ASBLY
2-23-2001A
11
1
28.4V
14.2V
14.2V
116.6V
515
206A
SCI
541A
326
543
206B
353
GENERAL INFORMATION
CAVITY NUMBERING SEQUENCE
(COMPONENT SIDE OF P.C. BOARD)
1
2
1
J7
1
16
J5
9
TO
WORK
CAVITY
J13
WIRE FEED
SPEED
C1 THRU C3
31,000 MFD
50V
4
-
U
515B
555
206B
206
204S
3
2
SCR HEATSINK
ASSEMBLY
THERMOSTAT
8
7
6
5
4
3
L10980
204
G1
X7
325A
324
SCI
390
FOR SPOOL GUN OPTION
OUTPUT
CHOKE
+
X4
206B
G2
209S
H4
**
COLOR CODE:
H5
GUN
TRIGGER
POWER
TRANSFORMER
4
2
324
325
324
H3
J3
7
7
5
209R
320B
W
G1
3
4
1
2
3
4
7
CURRENT AND DUTY CYCLE OF IMMEDIATE AND
FUTURE APPLICATIONS.
5
3
-
N.B. THIS DIAGRAM SHOWS THE "ELECTRODE" POLARITY
SNUBBER
BOARD
D2
BAFFLE
MOUNTED
RECTIFIER
DIODE
BRIDGE
W
207
B
205
390
10
256
206S
205
352
X9
**
325B
DISPLAY
BOARD
X5
208R
209R
354
8
12
2
3
4
8
6
5
7
14
15
16
J12
1
2
209
208
206
354
325B
GND
320
353
252
2
1
4
2
3
13
12
10
6
5
1
2
208R
208
204S
209S
500
256
551
552
206B
251
555
X8
515B
G2
325
J11
1
1
2
3
X8
3
4
C3
+
C2C1
X2
X3
R4
INDICATES CONNECTOR CAVITY NO.
U - BLUE
R - RED
W - WHITE
B - BLACK
SECONDARY VOLTAGES SHOWN
ARE NO LOAD RMS VALUES
OUTPUT CHOKE
THERMOSTAT
++
B
206S
L1
H2
H5
5
R
H4
H1
4
2
1
3
H1
LINE
SWITCH
S1
RECONNECT
PANEL
(SHOWN CONNECTED
FOR 230V)
TO SINGLE PHASE
SUPPLY LINE
TO GROUND PER
NATIONAL ELECTRICAL
CODE
ARC
VOLTAGE
10
6
5
1
J4
4
3
14
8
252
253
5
4
2
FOR TIMER
OPTION
6
GAS
SOLENOID
4
3
2
1
261
263
204
L2
15 OHMS
100 W
R1
204B
+
208S
6
R.F. FILTER
SCR 2
254A
R3
FAN
MOTOR
392
254253
X6
X7 X7
X1
H1
H2
H1H3
H4
W
B
L2L1
**
1
6
8
9
10
J5
28.4V
J6
320
**
R.F.
CHOKE
AS’BLY
GND
4
9
10
11
12
13
1
2
3
4
5
J7
5
6
J8
515B
550
X6
NOTES:
N.A. WELDING CABLE MUST BE OF PROPER CAPACITY FOR THE
J1
2
108
(NON-LEAD SIDE OF CONNECTOR)
21
J10
1
711
J2
J4
6
7
8
3
9
1
10
5
7
8
9
260
264
267
265
14
11
J2
J1
9
8
1
2
CONTROL BOARD
6
7
8
X9
X9
X5
POWER FACTOR
ENHANCEMENT
CHOKE
251
325
1J6
J8 J9
65
4
6
1
J3
NUMBERING SEQUENCE
12
7
J12
8
2
J11
J13
4
3
1
352
J10
POWER MIG 255 (230/460/575V)
515
500
551
550
552
ELECTRICAL SYMBOLS PER E1537
SCR 1
SCR HEATSINK
MOTOR/
GEARBOX
B
X6
X5
X8
CONDUCTOR STRAP AND WORK STUD.
OFF AND REVERSE LEAD CONNECTIONS AT CABLE
"POSITIVE". TO CHANGE POLARITY, TURN THE UNIT
392
W
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.
G-4
ELECTRICAL DIAGRAMS
POWER MIG 255
G-4
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
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WIRING DIAGRAM - ENTIRE MACHINE - CODE 10986 - (L11980)
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.
L11980
A
COLOR CODE:
ELECTRICAL SYMBOLS PER E1537
GENERAL INFORMATION
4
5
J7
9
8
7
6
265
263
260
261
U - BLUE
R - RED
W - WHITE
B - BLACK
INDICATES CONNECTOR CAVITY NO.
262
267
264
OUTPUT
CHOKE
POWER FACTOR
ENHANCEMENT
CHOKE
204B
FOR SPOOL GUN OPTION
SECONDARY VOLTAGES SHOWN
ARE NO LOAD RMS VALUES
1
2
3
10
C3C1
205206S
206B
R1
SCR HEATSINK
ASSEMBLY
THERMOSTAT
116.6V
14.2V
14.2V
28.4V
C2
+++ C1 THRU C3
31,000 MFD
50V
15 OHMS
100 W
+
-
320B
1
J10
J10
390 392
J1 J4
J6
J8 J9 J7
10
J2 J5
1
3
J3
CAVITY NUMBERING SEQUENCE
(COMPONENT SIDE OF P.C. BOARD)
251
206
FOR TIMER
OPTION
28.4V
J9
R.F. FILTER
SCR HEATSINK
ASBLY
SCR 2
G1
208S
204S
G2
SCR 1
209S
1
2
3
208S
208
208R
209S
204S
8
7
6
5
4
209R
209
252
WIRE FEED
SPEED
R3
256
8
6
5
1
ARC
VOLTAGE
252254253256
R4
254A
550
551
4
2
7
WIRE FEED
SPEED
3
R3
DISPLAY
BOARD
515
552
500
8
4
7
6
3
5
2
1
ARC
VOLTAGE WIRE FEED
SPEED
252254253256
R4
254A
DISPLAY
BOARD
500
515
551
552
550
R3
POWER
TRANSFORMER
SCR 1
G1
208S
G2
204S
TO GROUND PER
NATIONAL ELECTRICAL
CODE
SCR 2
ASBLY
SCR HEATSINK
209S
WIRE FEED
SPEED
253
R4
ARC
VOLTAGE
252254256
R3
254A
G2
SCR 1
SCR HEATSINK
ASBLY
SCR 2
204S
209S
G1
208S
SCR 2
ASBLY
SCR HEATSINK
SCR 1
G2
G1
208S
204S
209S
-
+
208R
209R
-
+
254A
R3
252254256
WIRE FEED
SPEED
8
7
6
5
4
3
2
1
ARC
VOLTAGE
DISPLAY
BOARD
253
R4
500
515
550
551
552
209R
+
-
208R
354
J11
1
2
3
4
325
324
325
4
2
GUN
TRIGGER
324
5
2
3
2
4
1
2
3
2
5
5
2
3
4
7
11
6
3
8
9
2
5
4
J8
252
550
254
500
J4
4
7
6
14
11
1
J5
J6
1
1
11
10
9
8
6
GND
X6
X5
515
206B
B
392
2
3
4
7
8
9
10
3
5
206
205
320
326
541A
543
SCI
SCI
515
206A
8
6
14
15
16
6
325A
5
W
206S
207
353
X8
325B
X9
352
4
10
12
13
7
12
354
G2
204
G1
X7
390
325
555
1
J2
6
7
8
9
J1
10
1
515B
324
208
CONTROL BOARD
12
13
1
J3
253
251
552
551
256
209
GND
352
353
252
R4
254A
256 253 254
DISPLAY
BOARD
WIRE FEED
SPEED
R3
8
7
6
5
4
3
1
ARC
VOLTAGE
515
2
551
552
550
500
209R
+
354 208R
-
515B
555
206B
253
R4
254256
254A
ARC
VOLTAGE
254A
POWER
TRANSFORMER
204S
208S
G1
SCR HEATSINK
ASBLY
SCR 2
G2
209S
SNUBBER
BOARD
X2 ASBLY
SCR HEATSINK
D1
R.F. FILTER
209S
X8
D2
BAFFLE
MOUNTED
RECTIFIER
DIODE
BRIDGE
354
+
G1
208S
204S
SCR 2
X3
X4
POWER
TRANSFORMER
G
207
X9
X5
X5
X6
X6
X7
X7
X1
X9
X8
208R
-
209R
TO
WORK
SCR 1
G2
352
353
FAN
MOTOR
TO
WORK
J3
252254253256
TO
WORK
207
R.F. FILTER
500
515
550
551
ARC
VOLTAGE
252254253256
R3R4
DISPLAY
BOARD
254A
552
WIRE FEED
SPEED
8
7
6
5
4
3
2
1
254A
252254253256
R3
R4
ARC
VOLTAGE WIRE FEED
SPEED
325B
OUTPUT CHOKE
THERMOSTAT
320
J11 **
N.A. WELDING CABLE MUST BE OF PROPER CAPACITY FOR THE
FUTURE APPLICATIONS.
NOTES:
CONDUCTOR STRAP AND WORK STUD.
OFF AND REVERSE LEAD CONNECTIONS AT CABLE
"POSITIVE". TO CHANGE POLARITY, TURN THE UNIT
CURRENT AND DUTY CYCLE OF IMMEDIATE AND
N.B. THIS DIAGRAM SHOWS THE "ELECTRODE" POLARITY
GAS
SOLENOID
CONTROL BOARD
POWER MIG 255 (230/460/575 V)
2
1
5 8
4
1
8
1
9
16
1
3
4
6
8
1
14
7
1
12
7
6
10
6
5
1
CAVITY
1
**
(NON-LEAD SIDE OF CONNECTOR)
2
34
NUMBERING SEQUENCE
J11
1
2
3
8
7
6
5
4
W
B
H2
5
4
2
1
3
TO SINGLE PHASE
SUPPLY LINE
H1H3
H4
W
B
H5
H2
L2L1
H1
H1
H3
H4
RECONNECT
PANEL
(SHOWN CONNECTED
FOR 230V)
LINE
SWITCH
S1
L2
L1
H5
H1 H4
H1 H4
H4
H1 H4
H1
WIRE
DRIVE
MOTOR/
GEARBOX
B
W
T
A
C
H
B
R
U
B
R
U
W
B
J12
J12
204
G-5
ELECTRICAL DIAGRAMS
POWER MIG 255
G-5
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
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WIRING DIAGRAM - ENTIRE MACHINE - CODE 10990 - (L11979)
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.
L11979
A
COLOR CODE:
ELECTRICAL SYMBOLS PER E1537
GENERAL INFORMATION
4
5
J7
9
8
7
6
265
263
260
261
U - BLUE
R - RED
W - WHITE
B - BLACK
INDICATES CONNECTOR CAVITY NO.
262
267
264
OUTPUT
CHOKE
POWER FACTOR
ENHANCEMENT
CHOKE
204B
FOR SPOOL GUN OPTION
SECONDARY VOLTAGES SHOWN
ARE NO LOAD RMS VALUES
WIRE
DRIVE
MOTOR/
GEARBOX
1
2
3
10
C3C1
205206S
206B
R1
SCR HEATSINK
ASSEMBLY
THERMOSTAT
116.6V
14.2V
14.2V
28.4V
C2
+++ C1 THRU C3
31,000 MFD
50V
15 OHMS
100 W
B
+
-
320B
1
J10
J10
390 392
J1 J4
J6
J8 J9 J7
10
J2 J5
1
3
J3
CAVITY NUMBERING SEQUENCE
(COMPONENT SIDE OF P.C. BOARD)
251
206
FOR TIMER
OPTION
28.4V
J9
W
T
A
C
H
R.F. FILTER
SCR HEATSINK
ASBLY
SCR 2
G1
208S
204S
G2
SCR 1
209S
1
2
3
208S
208
208R
209S
204S
8
7
6
5
4
209R
209
252
WIRE FEED
SPEED
R3
256
8
6
5
1
ARC
VOLTAGE
252254253256
R4
254A
550
551
4
2
7
WIRE FEED
SPEED
3
R3
DISPLAY
BOARD
515
552
500
8
4
7
6
3
5
2
1
ARC
VOLTAGE WIRE FEED
SPEED
252254253256
R4
254A
DISPLAY
BOARD
500
515
551
552
550
R3
POWER
TRANSFORMER
LINE
SWITCH
S1
SCR 1
G1
208S
G2
204S
L2
L1
H4 H2
H3 L1
208V
230V H1 H4
H1
RECONNECT
PANEL
TO GROUND PER
NATIONAL ELECTRICAL
CODE
W
SCR 2
ASBLY
SCR HEATSINK
209S
L2
B
WIRE FEED
SPEED
253
R4
ARC
VOLTAGE
252254256
R3
254A
G2
SCR 1
SCR HEATSINK
ASBLY
SCR 2
204S
209S
G1
208S
SCR 2
ASBLY
SCR HEATSINK
SCR 1
G2
G1
208S
204S
209S
-
+
208R
209R
-
+
254A
R3
252254256
WIRE FEED
SPEED
8
7
6
5
4
3
2
1
ARC
VOLTAGE
DISPLAY
BOARD
253
R4
500
515
550
551
552
209R
+
-
208R
354
J11
1
2
3
4
325
324
325
4
2
GUN
TRIGGER
324
5
2
3
2
4
1
2
3
2
5
5
2
3
4
7
11
6
3
8
9
2
5
4
J8
252
550
254
500
J4
4
7
6
14
11
1
J5
J6
1
1
11
10
9
8
6
GND
X6
X5
515
206B
B
392
2
3
4
7
8
9
10
3
5
206
205
320
326
541A
543
SCI
SCI
515
206A
8
6
14
15
16
6
325A
5
W
206S
207
353
X8
325B
X9
352
4
10
12
13
7
12
354
G2
204
G1
X7
390
325
555
1
J2
6
7
8
9
J1
10
1
515B
324
208
CONTROL BOARD
12
13
1
J3
253
251
552
551
256
209
GND
352
353
252
R4
254A
256 253 254
DISPLAY
BOARD
WIRE FEED
SPEED
R3
8
7
6
5
4
3
1
ARC
VOLTAGE
515
2
551
552
550
500
209R
+
354 208R
-
515B
555
206B
253
R4
254256
254A
ARC
VOLTAGE
B
W
L2
H4H3 H2 L1
230V 208V
RECONNECT
PANEL
254A
H4 H2 L1
208V
RECONNECT
PANEL
H3
230V
L1
H1
L2
H4
H1
W
B
LINE
SWITCH
S1
L2
POWER
TRANSFORMER
204S
208S
G1
SCR HEATSINK
ASBLY
SCR 2
G2
209S
L2
L1
H4
H1
H1
H3
230V
H2
H4
208V
L1
RECONNECT
PANEL
W
LINE
SWITCH
S1
L2
B
SNUBBER
BOARD
X2
H1
ASBLY
SCR HEATSINK
D1
R.F. FILTER
209S
X8
D2
BAFFLE
MOUNTED
RECTIFIER
DIODE
BRIDGE
354
+
G1
208S
204S
SCR 2
H1
X3
H2
X4
H3
POWER
TRANSFORMER
H3 H2 L1
230V 208V
L2
RECONNECT
PANEL
G
207
LINE
SWITCH
S1
H4
H1
L2
L1
H4
TO SINGLE PHASE
SUPPLY LINE
B
W
X9
X5
X5
X6
X6
X7
X7
X1
X9
X8
208R
-
209R
TO
WORK
SCR 1
G2
352
353
FAN
MOTOR
TO
WORK
J3
252254253256
TO
WORK
207
R.F. FILTER
500
515
550
551
ARC
VOLTAGE
252254253256
R3R4
DISPLAY
BOARD
254A
552
WIRE FEED
SPEED
8
7
6
5
4
3
2
1
254A
252254253256
R3
R4
ARC
VOLTAGE WIRE FEED
SPEED
325B
OUTPUT CHOKE
THERMOSTAT
320
B
R
U
J11 **
N.A. WELDING CABLE MUST BE OF PROPER CAPACITY FOR THE
FUTURE APPLICATIONS.
NOTES:
CONDUCTOR STRAP AND WORK STUD.
OFF AND REVERSE LEAD CONNECTIONS AT CABLE
"POSITIVE". TO CHANGE POLARITY, TURN THE UNIT
CURRENT AND DUTY CYCLE OF IMMEDIATE AND
N.B. THIS DIAGRAM SHOWS THE "ELECTRODE" POLARITY
GAS
SOLENOID
CONTROL BOARD
POWER MIG 255 (208/230 V)
2
1
5 8
4
1
8
1
9
16
1
3
4
6
8
1
14
7
1
12
7
6
10
6
5
1
CAVITY
1
**
(NON-LEAD SIDE OF CONNECTOR)
2
34
NUMBERING SEQUENCE
J11
1
2
3
8
7
6
5
4
W
B
B
R
U
W
B
J12
J12
204
G-6
ELECTRICAL DIAGRAMS
POWER MIG 255
CONTROL PC BOARD SCHEMATIC - (G3520-1D1)
G-6
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
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.
G-7
ELECTRICAL DIAGRAMS
POWER MIG 255
CONTROL PC BOARD ASSEMBLY - (G3521-1)
Ch’ge. Sht. No.
3521-1
XE-RW
A
POWER MIG 255
CONTROL P.C. BOARD ASSEMBLY
C.S./
FULL
3521-1
12-18-98 G2803-1
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
EQUIP.
TYPE
SCALE
DR DATE CHK REF.
SUBJECT
SUP’S’D’G
SHT.
NO.
G
G
5.80
.20
3-12-99
7-9-99H
7-28-2000J
10-5-2001C
6.00
~.04
0
0.20 3.20 8.80
9.00
~.04
ITEM REQ’D PART NO. IDENTIFICATION
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXX
XXXXXXXXXXXXXX
XXXXXXXXXXXXX
XXX
X1
J1
J2
J3
J5
J6
J8
R74
R71
C24
C25
R72
R73
R83
D26
C29
D27
R75
R70
D21
D22
C22 X3
R69
R68
C23
R77
R76
R78
C46
R98 D33
D35
R101
L2
L1
R8
D3
D1
C1
R6
C2
R4
R5
R42
D31
D2
C44
R1
R2
R87
R92 C31
R91
R86 C30
R10
R11
R9
D4
D6
R12
D7
D5
Q7
C50
Q10
R54
C27
X12
C28
DZ1
D15
R55
R56
C16
DZ2
R52
R51
X10
X11
D14
R49
R50
R48
R53
Q5
Q4
D25
R81
R82
TP4
TP3
C35
C19
C18
DZ3
R105 X8
C7
C48
D13
R33
D12
R34
R40
DZ4
R107
D36
Q8
Q6
R106
Q9
Q3
R104
R32
X5
R28
R29
C8
R39
X9 C49
R36
R102
R103
R57
C15
C17
R47
R37
X4
R38
R35
C9
TP1
TP2
C5
C6
D10
D8
R27
R15
D9
C3
R14
R23
D11
C4
R94
R93
Q1
Q2
R24
R80
R20
R18
R60
R65
C32
C34
C33
D16
D29
X6
R61
D17
D18
R63
L3
L4
R67
R64
C20
R58
D20
D19
R62
R13
R22
C41
C36 C37
C40
C38
C39
X7
D28
R41
D23
D24
R79
R99
D34
R100
R95
C43
R90
R84
R43
R45
R44
X2
C10
C14
C54
TP7
C51
TRI1
C52
R109
R108
C53
Q11
R111
R110
C11
R46
C45
R97
R96
D30
D32
R31
R30
R19
R21
CONTROL G3521-1
R112
R113
C55
C56
C57
C12
C13
C47
OCI1
OCI2
R7
R3
Y1
C58
R116
R115
R25
R114
C26
R26
R117
J4
D37
R66
R59
R88
R89
OCI3
C1,C2,C8,C9,C14,C20,C29
C36,C37,C38,C39,C43,C44
C48,C52,C53,C55,C56
C3,C4,C11
C5,C6,C18,C19,C35,C51,C54
C7
C10,C22,C23,C24,C25,C30
C31,C32,C33,C34,C40,C41
C45,C46,C57,C58
C12,C13
C15
C16
C17,C28
C26
C27
C47
C49
C50
C59
D1,D2,D3,D31
D4,D5,D6,D7,D8,D9,D10,D11,D12,D13,D14,
D15,D16,D17,D18,D19,D20,D21,D22,D24
D25,D26,D27,D28,D29,D30
D32,D33,D34,D35,D36
D23,D37
DZ1
DZ2,DZ3,DZ4
J1
J2
J3
J4
J5
J6
J8
L1,L2,L3,L4
OCI1,OCI2
OCI3
Q1,Q2,Q3,Q6,Q11
Q4
Q5,Q9
Q7,Q10
Q8
R1,R2,R6,R41,R42,R65,R75
R79,R84,R112,R113
R3,R7,R25,R26,R114,R117
R4,R51
R5,R9,R12,R30,R35,R45,R70
R90
R8,R115
R10,R11,R62,R63,R76,R77
R78,R82,R95,R105
R13,R22,R93,R94
R14,R15,R23,R27
R18,R20,R24,R80
R19,R21,R58,R83
R28,R46,R61
R29,R100,R110
R31,R106
R32
R33,R37,R38
R34,R40
R36
R39,R68,R71,R72,R91,R92
R111
R43
R44,R109
R47
R48
R49,R50
R52,R98
R53
R54
R55,R56
R57,R108
R59,R66,R69,R73,R74,R86,R87
R60
R64,R67
R81
R88,R89
R96,R103
R97
R99
R101,R102
R104
R107
R116
TP1,TP2
TP3,TP4
TP7
TRI1
X1
X2
X3
X4,X5
X6
X7
X8
X9
X10,X11
X12
Y1
18
3
7
1
16
2
1
1
2
1
1
1
1
1
1
4
31
2
1
3
1
1
1
1
1
1
1
4
2
1
5
1
2
2
1
11
6
2
8
2
10
4
4
4
4
3
3
2
1
3
2
1
7
1
2
1
1
2
2
1
1
2
2
7
1
2
1
2
2
1
1
2
1
1
1
2
2
1
1
1
1
1
2
1
1
1
1
2
1
1
1.0/35
20/50
22pF/100
39/10
3300/50
18/15
2200/63V
820pF/50
0.27/63V
1N4007
1N4004
1N5818
1N4735
1N4746A
HEADER
HEADER
HEADER
HEADER,VERTICAL
HEADER
HEADER
HEADER
330uH
OPTOCOUPLER,TRIACDRV,RANDOM,800V
2N4401
HEATSINK ASBLY
NPN TRANSISTOR
TRANSISTOR,NMF,T220,45A,100V(SS)
2N4403
120 2.5W
15K 1/4W
4.75K
4.75K 7/16W
1.21K 1/4W
1.21K 1/4W
681 1/4W
562 1/4W
2.21K 1/4W
6.81K 1/4W
5.62K 1/4W
26.7K 1/4W
22.1K 1/4W
2.67K 1/4W
3.01K 1/4W
5.11K 1/4W
267 1/4W
24.3K 1/4W
511 1/4W
16.2K 1/4W
47.5K 1/4W
16.5K 1/4W
13.7K 1/4W
750 1/4W
475 1/4W
28.0K 1/4W
15J
20J
MOV,120J
T2500D
IC,S8054HN,CMOS,UNDERVOT-SENSING(SS)
14 PINI.C.(SS)
IC,SWITCH,LO-SIDE(SS)
MC14584(SS)
+5V REG.
.022/50
.1/50
.0047 OR .005/1400
ROM ASSEMBLY (SS)
S16668-5
S13490-42
T11577-52
S13490-73
S16668-11
S16668-1
S13490-30
S13490-92
S13490-39
T11577-28
S13490-118
S16668-7
S13490-76
S13490-102
S24833-1
T12199-2
T12199-1
T12705-23
T12702-40
T12702-45
S18248-8
S18248-14
S18248-12
S24020-10
S18248-16
S18248-6
S18248-2T
T12218-7
S15000-30
S15000-31
T12704-68
S18105-4
T12704-35
T12704-88
T12704-69
S19400-1002
S24002-1200
S19400-1502
S19400-4751
S19400-1211
S19400-1000
S19400-6810
S19400-15R0
S19400-5620
S19400-2211
S19400-6811
S19400-1501
S19400-5621
S19400-2672
S19400-2212
S19400-33R2
S19400-2671
S19400-3321
S19400-1004
S19400-1001
S19400-1301
S19400-2801
T14648-22
S19400-3011
S19400-5111
T12300-75
S19400-26R7
S19400-2670
S19400-4422
S19400-2432
S19400-5110
T14648-5
S19400-1622
S19400-4752
T14648-19
S19400-1652
S19400-1372
S19400-7500
S19400-4750
S19400-2802
T13640-15
T13640-9
T13640-18
S15161-27
S24392-4
M15102-3
S17900-8
S15128-11
S15128-16
S23060-1
S15018-4
S15018-6
S15128-10
S15128-5
S16665-5
.25 OHM, 7W RESISTOR
.047/100
.001/400
.22/100
OPTOCOUPLER TRIAC DRIVER 800V
10K 1/4W
100 1/4W
15 1/4W
1.5K 1/4W
33.2 1/4W
3.32K 1/4W
1M 1/4W
1K 1/4W
1.3K 1/4W
2.8K 1/4W
50 5W
26.7 1/4W
44.2K 1/4W
3.3K 5W
1K 5W
14 PIN QUAD COMPARATOR
IC,LT1014,LINEAR INTEGRATED CIRCUIT
DIGITAL INTEGRATED CIRCUIT(SS)
IC,431,VOLTAGE REF.
8.0 MHZ
11-16-2001D
G-7
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
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.
G-8
ELECTRICAL DIAGRAMS
POWER MIG 255
G-8
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
DISPLAY PC BOARD SCHEMATIC - (L10951)
500
475
R10
DISP2
2
1
4
9
5
10
7
6
83
LED3
X5
1213
J10
4
DISP3
2
1
4
9
5
10
7
6
83
14
3
Rx
Vdd
d
BANK1
g
DATA OUT
f
CLOCK
MC14489
DATA IN
h
Vss
BANK3
BANK4
BANK2
a
/ENABLE
e
c
BANK5
b
X3
18
9
17
6
5
2
10
19
8
1
13
12
16
20
11
15
4
7
1.50K
R11
J10
6
X5
2
1
500
500
LATCH
WITHOUT AFFECTING THE INTERCHANGEABILITY OF A COMPLETE BOARD, THIS DIAGRAM MAY
NOT SHOW THE EXACT COMPONENTS OR CIRCUITRY OF CONTROLS HAVING A COMMON CODE
LABELS
C-
SUPPLY
R-
LED- 3
DISP1
2
1
4
9
5
10
7
6
83
D-
SCHEMATIC, DISPLAY PCB
10
1
POWERMIG 255
EARTH GROUND CONNECTION
SUBJECT
EQUIP.
NONE
CLEVELAND, OHIO U.S.A.
2/20/98
CHK.
DISP- 7
7805
L
515
500
J10
8
221
R14
221
R4
221
R1
221
R2
221
R13
D1
18
15V
C2
GND
IN
OUT
X1
221
R3
4.7
35V
C1
MC14489
Vss
Vdd
X3
3
14
HEXINV
X5
14
7
50V
0.1
C4
50V
0.1
C3
MC14489
Vss
Vdd
X4
3
14
X5
43
1.50K
R12
X5
65
50V
0.1
C10
500
500
500
+5VA
10951
J10
7
VOLTS
J10
5
10K
R7
50V
.0047
C8
X5
10
11
475
R8
50V
.0047
C7
X5
89
10K
R6
10K
R5
475
R9
DISP7
2
1
4
9
5
10
7
6
83
DISP6
2
1
4
9
5
10
7
6
83
500
500
500
14
3
Rx
Vdd
d
BANK1
g
DATA OUT
f
/ENABLE
MC14489
DATA IN
h
Vss
BANK3
BANK4
BANK2
a
CLOCK
e
c
BANK5
b
X4
18
9
17
6
5
2
11
19
8
1
13
12
16
20
10
15
4
7
SCK
MOSI
DISP5
2
1
4
9
5
10
7
6
83
DIODES =
GENERAL INFORMATION
ELECTRICAL SYMBOLS PER E1537
X- 5
50V
.0047
C9
L
NO.
TYPE
SHT.
SUP’S’D’G.
DR.
GT
VOLTAGE NET
FRAME CONNECTION
COMMON CONNECTION
UNLESS OTHERWISE SPECIFIED)
(UNLESS OTHERWISE SPECIFIED)
10951
LAST NO. USED
POWER SUPPLY SOURCE POINT
14
UNLESS OTHERWISE SPECIFIED)
Ch’ge.Sht.No.
NOTES :
N.A. SINCE COMPONENTS OR CIRCUITRY ON A PRINTED CIRCUIT BOARD MAY CHANGE
NUMBER.
FILENAME: L10951-1AB
1/4W
.022/50V
1A, 400V
(
MFD
CAPACITORS =
RESISTORS = Ohms (
DATE
SCALE
THE LINCOLN ELECTRIC CO.
XA
3-12-99
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.
G-9
ELECTRICAL DIAGRAMS
POWER MIG 255
G-9
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
DISPLAY PC BOARD ASSEMBLY - (L10952-1)
10952-1
Ch’ge. Sht. No.
XA
3-12-99
A
B
POWER MIG 255
R.T.
FULL
10952-1
5-20-98
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
EQUIP.
TYPE
SCALE
SUBJECT
DR DATE CHK REF. SUP’S’D’G
SHT.
NO.
L
L
IDENTIFICATION
PART NO.
REQ’DITEM
.49
0
5.80
~.04
.20
0
STANDARD DISPLAY P.C. BD. ASSEMBLY
1.44
1.64
~.04
5.60
2.90
C1 1 S13490-25 4.7/35
C2 1 S13490-39 18/15
C3,C4,C10 3 S16668-11 .1/50
C7,C8,C9 3 S16668-6 4700pF/50
D1 1 T12199-1 1N4004
DISP1,DISP2,DISP3,DISP5 6 S17395-2 DISPLAY
DISP6,DISP7
J10 1 S20380-8 RT ANGLE HEADER
LED3 1 T13657-6 RED LED
R1,R2,R3,R4,R13,R14 6 S19400-2210 221 1/4W
R5,R6,R7 3 S19400-1002 10K 1/4W
R8,R9,R10 3 S19400-4750 475 1/4W
R11,R12 2 S19400-1501 1.5K 1/4W
X1 1 S15128-5 +5V REG.
X3,X4 2 S20496-1 IC,MC14489,CMOS,DRIVER,LED,CC,MCU(SS)
X5 1 S17900-8 14 PIN I.C. (SS)
DISPLAY
L10952-1
DISP1 DISP2 DISP3 DISP5 DISP6 DISP7
C1
X1
R10
C9
X5
R9
R5
R6
R7
R8
C8
D1
X3
X4
R12
R11
C10
C4
C3
C2
R1
R2
R13
R3
R4
R14
J10
C7
LED3
4-28-2000D
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.
G-10
ELECTRICAL DIAGRAMS
POWER MIG 255
SNUBBER PC BOARD SCHEMATIC - (S24374)
204S
J1
1
J1
8
5W
10
R1
J1
6
J1
2
J1
3
J1
4
400V
.68
C2
J1
5
J1
7
5W
10
R2
24374
209R
SNUBBER BOARD
NONE
.022/50V
MFD
UNLESS OTHERWISE SPECIFIED)
POWER SUPPLY SOURCE POINT
POWERMIG 255
N.A.
OF A COMPLETE
(
CONTROLS HAVING A COMMON
CODE NUMBER.
NOTES :
BOARD.
SHOW THE EXACT COMPONENTS
UNLESS OTHERWISE SPECIFIED)
CHK.
THE INTERCHANGEABILITY
24374
S
WITHOUT AFFECTING
DIODES =
ELECTRICAL SYMBOLS PER E1537
CIRCUIT BOARD
EARTH GROUND CONNECTION
MAY CHANGE
SINCE COMPONENTS OR CIRCUITRY ON
SCALE
SUP’S’D’G.
FRAME CONNECTION
LABELS
GENERAL INFORMATION
EQUIP.
1/4W
CAPACITORS =
VOLTAGE NET
THE LINCOLN ELECTRIC CO.
DATE
DR. NO.
SHT.
OR CIRCUITRY OF
Ch’ge.Sht.No.
S
MAB
SUBJECT
CLEVELAND, OHIO U.S.A.
TYPE
COMMON CONNECTION
(UNLESS OTHERWISE SPECIFIED)
RESISTORS = Ohms (
THIS DIAGRAM MAY NOT
A PRINTED
SUPPLY
1A, 400V
209S
209
208S
208
208R
400V
.68
C1
5-12-98
204
XB-RW
3-12-99
G-10
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
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.
G-11
ELECTRICAL DIAGRAMS
POWER MIG 255
G-11
Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC
Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
SNUBBER PC BOARD ASSEMBLY - (M19248-1)
19248-1
Ch’ge. Sht. No.
XB
3-12-99
B
SP WELDERS
SNUBBER P.C. BOARD AS’BLY
R.T.
FULL
19248-1
5-13-98
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
EQUIP.
TYPE
SCALE
SUBJECT
DR DATE CHK REF. SUP’S’D’G
SHT.
NO.
M
M
IDENTIFICATION
PART NO.
REQ’D
CAPACITORS = MFD/VOLTS
0
~.04
0
ITEM
M16647-1
2.00
C1,C2 2 T11577-68 0.68 MFD /400 WVDC CAPACITOR
J1 1 S18248-8 HEADER
R1,R2 2 T14648-25 10 5W
.20
3.80
.20 1.80
4.00
~.04
M19248-1
SNUBBER
J1
R1
R2
C1
C2
1-12-2001D
A
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.
SVM ERROR REPORTING FORM
We need to know if there are errors in our manuals. We also value any suggestions as to
additional tests or procedures that would make this SVM a better tool for you.
If you discover new or different “Problems or Symptoms” that are not covered in the three col-
umn troubleshooting chart, please share this information with us. Please include the
machine’s code number and how the problem was resolved.
Thank You,
Technical Services Group
Lincoln Electric Co.
22801 St. Clair Ave.
Cleveland, Ohio 44117-1199
FAX 216-481-2309
SVM Number ___________________________
Page Number if necessary__________________
Your Company__________________________
Your Name_____________________________
Please give detailed description below:
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
SD287 04/06
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