AUTO ARC 255 Service manual

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October, 2006
POWER MIG 255C
For use with machines having Code Number : 11192, 11218
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Lincoln arc welding and cutting
equipment is designed and built
with safety in mind. However,
your overall safety can be
increased by proper installation
. . . and thoughtful operation on
your part. DO NOT INSTALL,
OPERATE OR REPAIR THIS
EQUIPMENT WITHOUT READING THIS MANUAL AND THE
SAFETY PRECAUTIONS CONTAINED THROUGHOUT. And,
most importantly, think before
you act and be careful.
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SERVICE MANUAL
Copyright © 2006 Lincoln Global Inc.
• World's Leader in Welding and Cutting Products •
• 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
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i
SAFETY
WARNING
CALIFORNIA PROPOSITION 65 WARNINGS
Diesel engine exhaust and some of its constituents
are known to the State of California to cause cancer, birth defects, and other reproductive harm.
The Above For Diesel Engines
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 Gasoline Engines
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.
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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.
FOR ENGINE
powered equipment.
1.h. To avoid scalding, do not remove the
radiator pressure cap when the engine is
hot.
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 welding arc or when the engine is running. Stop
the engine and allow it to cool before refueling to prevent spilled fuel from vaporizing on
contact with hot engine parts and igniting. Do
not spill fuel when filling tank. If fuel is spilled,
wipe it up and do not start engine until fumes
have been eliminated.
____________________________________________________
1.d. Keep all equipment safety guards, covers and devices in position 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.
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.
___________________________________________________
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.
2.d.5. Do not work next to welding power source.
Mar ‘95
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ELECTRIC SHOCK can kill.
ARC RAYS can burn.
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.
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.
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.
4.b. Use suitable clothing made from durable flame-resistant
material to protect your skin and that of your helpers from
the arc rays.
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.
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.
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.
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ii
SAFETY
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. The operation of welding fume control equipment is affected
by various factors including proper use and positioning of the
equipment, maintenance of the equipment and the specific
welding procedure and application involved. Worker exposure level should be checked upon installation and periodically thereafter to be certain it is within applicable OSHA PEL
and ACGIH TLV limits.
5.c. 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 products.
5.d. 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.
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5.e. 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.f. Also see item 1.b.
AUG 06
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iii
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.
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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.
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iii
SAFETY
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.
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.
• A safe 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.
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.
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iv
SAFETY
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 suivantes:
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 metallique ou des grilles metalliques, principalement dans
les positions assis ou couché pour lesquelles une grande
partie du corps peut être en contact avec la masse.
c. Maintenir le porte-électrode, la pince de masse, le câble de
soudage et la machine à souder en bon et sûr état defonctionnement.
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:
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
a. Utiliser un bon masque avec un verre filtrant approprié ainsi
qu’un verre blanc afin de se protéger les yeux du rayonnement de l’arc et des projections quand on soude ou
quand on regarde l’arc.
b. Porter des vêtements convenables afin de protéger la peau
de soudeur et des aides contre le rayonnement de l‘arc.
c. Protéger l’autre personnel travaillant à proximité au
soudage à l’aide d’écrans appropriés et non-inflammables.
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.
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, pantalons sans revers, et chaussures montantes.
3. Avant de faires des travaux à l’interieur de poste, la debrancher à l’interrupteur à la boite de fusibles.
2. Autant que possible, I’installation et l’entretien du poste seront
effectués par un électricien qualifié.
4. Garder tous les couvercles et dispositifs de sûreté à leur place.
5. Toujours porter des lunettes de sécurité dans la zone de
soudage. Utiliser des lunettes avec écrans lateraux dans les
Mar. ‘93
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MASTER TABLE OF CONTENTS
FOR ALL SECTIONS
Page
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
POWER MIG 255C
P-514
INSTALLATION
SECTION A
TABLE OF CONTENTS
-INSTALLATION SECTIONInstallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section A
Technical Specifications — POWER MIG 255C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-2
Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-3
Uncrating the POWER MIG 255C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-3
Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-3
Input Power, Grounding and Connection Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-3
Dual Voltage Machine Input Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-4
Triple Voltage Machine Input Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-5
Output Polarity Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-5
Gun and Cable Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-6
Shielding Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-6
Auxiliary Power Receptacles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-6
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SECTION A
POWER MIG 255C
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A-2
A-2
INSTALLATION
TECHNICAL SPECIFICATIONS – POWER MIG 255C
INPUT – SINGLE PHASE ONLY
Standard Voltage/Frequency Input Current @ 200 Amp Rated Output Input Current @ 250 Amp Rated Output
208/230/60 Hz
*47/44 Amps
56/52
230/460/575/60 Hz
41/20/16 Amps
50/24/19
RATED OUTPUT
Duty Cycle
40%
60%
100%
Amps
250 Amps
200 Amps
145 Amps
Volts at Rated Amperes
26 Volts
28 Volts
26 Volts
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OUTPUT
Welding Current Range
(Continuous)
30 – 300 Amps
Maximum Open Circuit Voltage
Welding Voltage Range
40 Volts
10-28 Volts
RECOMMENDED INPUT WIRE AND FUSE SIZES
Input Voltage/
Frequency (Hz)
Fuse or Breaker
Size (Super Lag)
Input Ampere
Rating On
Nameplate
208/60
230/60
460/60
575/60
60
60
30
25
56
52
24
19
75°C Copper Wire
in Conduit
AWG (IEC) Sizes
(For lengths
up to 100 ft)
8 (10 mm2)
10 (6 mm2)
14 (2.5 mm2)
14 (2.5 mm2)
75°C Copper Wire
in Conduit
AWG (IEC) Sizes
(For lengths
exceeding 100 ft)
6 (16 mm2)
8 (10 mm2)
12 (4 mm2)
12 (4 mm2)
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NOTE: Use #10 AWG Grounding Wire
PHYSICAL DIMENSIONS
Height
31.79 in.
808 mm
Width
18.88 in.
480 mm
Depth
38.78 in.
985 mm
Weight
220 Ibs
100 kg
WIRE SPEED RANGE
Wire Speed
50 – 700 IPM (1.27 – 17.8 m/minute)
POWER MIG 255C
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A-3
Read entire installation section before starting
installation.
INPUT POWER, GROUNDING AND
CONNECTION DIAGRAMS
SAFETY PRECAUTIONS
WARNING
WARNING
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts such as
output terminals or internal wiring.
ELECTRIC SHOCK can kill.
• Only qualified personnel should perform this
installation.
• Only personnel that have read and understood the POWER MIG 255C Operating
Manual should install and operate this equipment.
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• The POWER MIG power switch is to be in the
OFF position when installing work cable and
gun and when connecting other equipment.
------------------------------------------------------------------------
UNCRATING THE POWER MIG 255C
Cut banding and lift off cardboard carton. Cut banding
holding the machine to the skid. Remove foam and corrugated 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.
• All input power must be electrically disconnected before proceeding.
-----------------------------------------------------------------------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 specified 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 connected for the highest voltage. If the welder is to
be operated on lower voltage, it must be reconnected according to the instructions in Figure A.1
for dual voltage machines and Figure A.2 for
triple voltage machines.
WARNING
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LOCATION
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• Machine must be grounded per any national,
local or other applicable electrical codes.
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A-3
INSTALLATION
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 passages and cause overheating.
Make certain that the input power is electrically
disconnected before removing the screw on the
reconnect panel access cover.
------------------------------------------------------------------------
POWER MIG 255C
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A-4
INSTALLATION
A-4
FIGURE A.1 — DUAL VOLTAGE MACHINE INPUT CONNECTIONS.
3. The 208/230 volt 60 Hz model POWER MIG is
shipped with a 10 ft. input cable and plug connected 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.
4. Using the instructions in Figure A.3, have a qualified electrician connect the receptacle or cable to
the input power lines and the system ground per
the U.S. National Electrical Code and any applicable 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 diagram. 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.
POWER MIG 255C
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A-5
INSTALLATION
FIGURE A.2 — TRIPLE VOLTAGE MACHINE INPUT CONNECTIONS.
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FIGURE A.3 — RECEPTACLE DIAGRAM.
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A-5
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 connection of the two cables located in the wire drive compartment 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 connected to the positive (+) labeled terminal.
POWER MIG 255C
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A-6
GUN AND CABLE INSTALLATION
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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.
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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 keyways are aligned, insert and tighten retaining ring.
• 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 Z49.1, “Safety in Welding and Cutting” published by the American Welding Society.
---------------------------------------------------------------------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.
WARNING
Be sure to keep your face away from the valve outlet 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% CO2 cylinder, 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 CO2 cylinder.
5. Attach one end of the inlet gas hose to the outlet
fitting of the flow regulator, the other end to the
POWER MIG 255C rear fitting, and tighten the
union nuts securely with a wrench.
6. Before opening the cylinder valve, turn the regulator adjusting knob counterclockwise until the
adjusting spring pressure is released.
SHIELDING GAS
(For Gas Metal Arc Welding Processes)
Customer must provide cylinder of appropriate type
shielding gas for the process being used.
A gas flow regulator, for CO2 or Argon blend gas, and
an inlet gas hose are factory provided with the POWER
MIG 255C. Install the shielding gas supply as follows:
1. Set gas cylinder on rear platform of POWER MIG
255C. Hook chain in place to secure cylinder to
rear of welder.
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CYLINDER may explode if
damaged.
WARNING
1. Lay the cable out straight.
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WARNING
The Magnum 250L gun and cable provided with the
POWER MIG 255C 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 provided) if this wire size is being used.
Turn the welder power switch off before installing
gun and cable.
------------------------------------------------------------------------
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A-6
INSTALLATION
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.
7. Standing to one side, open the cylinder valve
slowly a fraction of a turn. When the cylinder pressure gauge pointer stops moving, open the valve
fully.
WARNING
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.
AUXILIARY POWER RECEPTACLES
(For 208/230V Models only)
This machine is equipped with 15Amp 120V receptacle with
15Amp Circuit Breaker. The receptacle is UL and CSA
approved.
POWER MIG 255C
OPERATION
SECTION B
TABLE OF CONTENTS
-OPERATION SECTIONOperation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section B
Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-3
Recommended Processes and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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
Wire Drive Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-6/B-7
Setting Run-In Speed on Standard Power MIG Feeder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-8
Fast or Slow Run-In Mode Selection (When Timer Option is not Installed) . . . . . . . . . . . . . . .
B-8
Instructions to Enter Slow Run-In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-8
Instructions to Enter Fast Run-In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-8
Making a Weld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-8
Avoiding Wire Feeding Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-9
Fan Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-9
Input Line Voltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-9
Wire Feed Overload Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-9
Welding Thermal Overload Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-10
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-10
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SECTION B
POWER MIG 255C
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B-2
Read entire Operation section before
operating the POWER MIG 255C.
WARNING
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts
or electrode with skin or wet
clothing. Insulate yourself from
work and ground.
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• Always
gloves.
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B-2
OPERATION
wear
dry
insulating
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.
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• Do not weld on closed containers.
ARC RAYS can burn eyes and
skin.
• Wear eye, ear and body protection.
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Observe all safety information throughout
this manual.
POWER MIG 255C
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B-3
B-3
OPERATION
PRODUCT DESCRIPTION
The POWER MIG™ 255C 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 microcomputerbased 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. The POWER MIG™ 255C is Spool Gun
ready and includes a second Gas Solenoid for Spool
Gun use. Refer to Accessories Section for Applicable
Spool Guns.
Other features include a 2" (51 mm) O.D. wire reel
spindle with adjustable brake, an integral gas cylinder
mounting undercarriage, an adjustable CO2 or Argon
blend flow regulator with cylinder pressure gauge and
inlet hose, a 15 ft. (4.6 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
control, a spot function, a selectable 4-step trigger
interlock and adjustable "Run In" for wire starting
optimization. Also optional are 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 255C is recommended for GMA
welding processes using 10 to 44 lb (4.5 to 20 kg) 2"
(51 mm) I.D. spools or Readi-Reel ® coils (with
optional adapter) of .025" through .045" (0.6 – 1.2 mm)
solid steel, .035" (0.9 mm) stainless, 3/64" (1.2 mm)
aluminum and .045" (1.2 mm) Outershield ® ; as well
as .035" (0.9 mm) and .045" (1.2 mm) Innershield®
self-shielding electrodes.
The POWER MIG 255C is factory equipped to feed
.035" (0.9 mm) and .045(1.2mm) electrode. It also
includes a 200A, 60% duty cycle (or 250A, 40% duty
cycle) rated, 15 ft. (4.6 m) GMAW gun and cable
assembly equipped for these wire sizes. Use of GMAW
processes requires a supply of shielding gas.
WARNING
WELDING CAPABILITY
The POWER MIG 255C 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
currents and capable of up to 300 Amps at lower duty
cycles.
LIMITATIONS
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The POWER MIG 255C WILL NOT operate
satisfactorily if powered with a portable or in-plant
generating system.
POWER MIG 255C
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B-4
OPERATION
mation also appears on the Procedure Decal on the
door inside the wire compartment.
DESCRIPTION OF CONTROLS
Power ON/OFF Switch — Place the lever in the "ON"
position to energize the POWER MIG 255C. 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 voltage. It
can be adjusted while welding over its 10 to 28 volt range.
Wire Speed Control — This controls the wire feed
speed from 50 – 700 inches per minute (1.2 – 17.8 m/min).
The control can be preset on the dial to the setting specified
on the Procedure Decal on the inside of the wire
compartment door. Wire speed is not affected when changes
are made in the voltage control.
WIRE SIZE CONVERSION PARTS
The POWER MIG 255C is rated to feed .025 through
.045" (0.6-1.2 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.
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WIRE DRIVE ROLL
The drive rolls installed with the POWER MIG 255C
have two grooves one for .035(0.9mm) wire Solid Steel
electrode and the other for .045(1.2mm) wire. Drive roll
size is stenciled on each side of the drive roll. If feeding problems occur, check to make sure that the wire
size and the drive roll size matches. See "Procedure
for Changing Drive Roll" in this section. This infor-
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FIGURE B.1— OPERATOR CONTROLS
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B-4
POWER MIG 255C
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B-5
PROCEDURE FOR CHANGING
DRIVE AND IDLE ROLL SETS
5. Rotate the spindle and adapter so the retaining spring is
at the 12 o'clock position.
1. Turn off the power source.
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.
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 assembly and
allow it to sit in an upright position.
7. Set one of the Readi-Reel inside cage wires on the slot in
the retaining spring tab.
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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 as shown below and remove the
drive roll. (See Figure B.2)
FIGURE B.2
5. Remove the inside wire guide plate.
6. 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.
9. Slide cage all the way onto the adapter until the retaining
spring "pops up" fully.
WARNING
--------------------------------------------------------------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.
2 IN. O.D.
SPINDLE
7. 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.
8. Replace the outside wire guide retaining plate by
tightening the two large knurled screws. Reposition
the adjustable pressure arm to its original position
to apply pressure. Adjust pressure as necessary.
WIRE REEL LOADING - READI
REELS, SPOOLS OR COILS
ADAPTER
RETAINING
SPRING
RETAINING
COLLAR
BRAKE
HOLDING
PIN
GROOVES
READI-REEL
INSIDE
CAGE
WIRES
RELEASE
BAR
To Mount 10 to 44 Lb. (4.5-20 kg) Spools (12"/300
mm Diameter) or 14Lb.(6 Kg) Innershield Coils:
(For 13-14 lb. (6 Kg) Innershield coils, a K435 Coil
Adapter must be used).
(For 10 lb.(4.5 Kg) 8 inch(203mm) diameter spools, a
K468 spindle 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.
1. Open the Wire Drive Compartment Door
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8. Lower the Readi-Reel to depress the retaining spring and
align the other inside cage wires with the grooves in the
molded adapter.
CHECK TO BE SURE THE RETAINING SPRING HAS
FULLY RETURNED TO THE LOCKING POSITION AND
HAS SECURELY LOCKED THE READI-REEL CAGE IN
PLACE. RETAINING SPRING MUST REST ON THE CAGE,
NOT THE WELDING ELECTRODE.
To Mount a 30 Lb. (14 kg) Readi-Reel Package (Using the
Molded Plastic K363-P Readi-Reel Adapter:)
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B-5
OPERATION
2. Depress the Release Bar on the Retaining Collar
and remove it from the spindle.
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.
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 so as to 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.
POWER MIG 255C
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B-6
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 output and to energize the wire feed motor.
FEEDING WIRE ELECTRODE
The pressure arm controls the amount of force the drive
rolls exert on the wire. Proper adjustment of both pressure
arm gives the best welding performance. For best results,
set both pressure arms to the same value.
Set the pressure arm as follows (See
Figure B.3):
Aluminum wires
Cored wires
Steel, Stainless wires
WARNING
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When triggering, the electrode and drive mechanism are electrically “hot” relative to work and
ground and remain “hot” several seconds after the
gun trigger is released.
------------------------------------------------------------------------
FIGURE B.3
CORED WIRES
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 assembly 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.
ELECTRIC SHOCK can kill.
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between 1 and 3
between 3 and 4
between 4 and 6
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.
IDLE ROLL PRESSURE SETTING
WARNING
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B-6
OPERATION
• Turn the input power OFF at the welding
power source before installation or
changing drive rolls and/or guides.
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode and
drive mechanism are "hot" to work and ground
and could remain energized several seconds
after the gun trigger is released.
• Only qualified personnel should perform maintenance work.
OUTERSHIELD
METALSHIELD
INNERS HIELD
SOLID WIRES
12
34
56
ALUMINUM
STEEL
STAINLE SS
WIRE DRIVE CONFIGURATION
(See Figure B.4)
Changing the Gun Receiver Bushing
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the welding power
source before installation or changing drive rolls
and/or guides.
• Do not touch electrically live parts.
•• When inching with the gun trigger, electrode and
drive mechanism are "hot" to work and ground
and could remain energized several seconds
after the gun trigger is released.
•• Only qualified personnel should perform maintenance work.
-----------------------------------------------------------------------Tools required:
• 1/4" hex key wrench.
Note: Some gun bushings do not require the use of
the thumb screw.
1. Turn power off at the welding power source.
2. Remove the welding wire from the wire drive.
3. Remove the thumb screw from the wire drive.
4. Remove the welding gun from the wire drive.
POWER MIG 255C
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B-7
B-7
OPERATION
5. Loosen the socket head cap screw that holds the
connector bar against the gun bushing.
Important: Do not attempt to completely remove
the socket head cap screw.
6. Remove the outer wire guide, and push the gun
bushing out of the wire drive. Because of the precision fit, light tapping may be required to remove
the gun bushing.
9. Rotate the gun bushing until the thumb screw hole
aligns with the thumb screw hole in the feed plate.
Slide the gun receiver bushing into the wire drive
and verify the thumb screw holes are aligned.
10. Tighten the socket head cap screw.
11. Insert the welding gun into the gun bushing and
tighten the thumb screw.
7. Disconnect the shielding gas hose from the gun
bushing, if required.
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8. Connect the shielding gas hose to the new gun
bushing, if required.
FIGURE B.4
THUMB SCREW
TORNILLO DE PULGAR
VIS DE POUCE
GUN RECEIVER BUSHING
BUJE DEL RECEPTOR DEL ARMA
DOUILLE DE R CEPTEUR DE PISTOLET
OUTER WIRE GUIDE
GUŒA DE ALAMBRE EXTERNA
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GUIDE DE C BLAGE EXTERNE
CONNECTOR BLOCK
BLOQUE DE CONECTADOR
BORNIER
SOCKET HEAD
CAP SCREW
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TORNILLO DE CASQUILLO
DE LA CABEZA DE Z CALO
VIS PRINCIPALE DE
LA DOUILLE CAP
LOOSEN
AFLOJE
TIGHTEN
APRIETAN
DESSERREZ-VOUS
POWER MIG 255C
SERRENT
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B-8
SETTING RUN-IN SPEED ON STANDARD POWER MIG FEEDER
FAST OR SLOW RUN-IN MODE
SELECTION,
MAKING A WELD
The POWER MIG 255C 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.
1. Check that the electrode polarity is correct for the
process being used, then turn the power switch ON.
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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
255C.
2. Turn the wire feed speed dial to minimum, fully counterclockwise.
3. With the gun trigger closed, turn the power ON at
the front panel of the POWER MIG 255C.
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4. The display will read "SLO run".
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INSTRUCTIONS TO ENTER FAST
RUN-IN
1. Turn power OFF on front panel of POWER MIG
255C.
2. Turn the wire feed speed dial to maximum, fully
clockwise.
3. With the gun trigger closed, turn the power ON at the
front panel of the POWER MIG 255C.
4. The display will read "FAS run".
NOTE:Arc starting characteristics may be effected
when using the fast run-in mode since optimum starting processes are being overridden.
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power down and return you to that same state upon
your next power up. Thus, you need only perform one
of the above procedures when you want to change the
run-in mode.
(When Timer Option is not installed)
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 seconds, whichever occurs first. After
which it will accelerate to the preset wire feed speed.
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B-8
OPERATION
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.
2. Set desired arc voltage and wire speed for the
particular electrode wire, material type and
thickness, and gas (for GMAW) being used. Use the
Application Chart on the door inside the wire
compartment 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 information pertaining
to Spot mode. That chart is also in this manual as
Figure B.5.
4. Press the trigger to feed the wire electrode through
the gun and cable and then cut the elec-trode within
approximately 3/8" (10 mm) of the end of the
®
contact tip [3/4" (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 supply
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".
It is not necessary to repeat either of the above
procedures each time the unit is powered up. The unit
will remember the run-in mode from the previous
POWER MIG 255C
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B-9
OPERATION
WARNING
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" (10 mm) [3/4" (20 mm) for
Outershield].
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10. To stop welding, release the gun trigger and then
pull the gun away from the work after the 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 255C.
Wire feeding problems can be avoided by observing
the following gun handling procedures:
a. Do not kink or pull cable around sharp corners.
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h. Use proper drive rolls and wire drive idle roll
pressure 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
minimum 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
temperature protection. (See Welding Thermal
Overload Protection)
INPUT LINE VOLTAGE PROTECTION
e. Use only clean, rust-free electrode. The Lincoln
electrodes have proper surface lubrication.
Replace contact tip when the arc starts to become
unstable or the contact tip end is fused or
deformed.
Low Line Voltage — You may not be able to get
maximum 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 255C has solid state overload
protection of the wire drive motor. If the motor becomes
overloaded, the protection circuitry turns off the wire
feed speed weld outputi 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.
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Keep the gun cable as straight as possible when
welding or loading electrode through cable.
c. Do not allow dolly wheels or trucks to run over
cables.
d. Keep cable clean by following maintenance
instructions.
f.
g. Keep wire reel spindle brake tension to minimum
required to prevent excess reel over-travel which
may cause wire "loop-offs" from coil.
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.
AVOIDING WIRE FEEDING
PROBLEMS
b.
B-9
POWER MIG 255C
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B-10
B-10
OPERATION
WELDING THERMAL OVERLOAD
PROTECTION
English Wire
The POWER MIG 255C has built-in protective
thermostats that respond to excessive temperature.
They open the wire feed and welder output circuits if
the machine exceeds the maximum safe operating
temperature because of a frequent overload, or high
ambient temperature plus overload. The thermostats
automatically reset when the temperature reaches a
safe operating level and welding and feeding are
allowed again, when gun is retriggered.
Part No.
Size1
Size
12' (3.6 m)
15' (4.5 m)
K533-7
K533-3
.035 – .045"
0.9 – 1.2 mm
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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
temperature rating before the thermostats can react.
FIGURE B.5 — WELDING PROCEDURE INFORMATION
70
80
90
100
110
Metric Wire
Length
120
Note: See inside cover of machine for additional, commonly used welding procedure information.
POWER MIG 255C
ACCESSORIES
SECTION C
TABLE OF CONTENTS
-ACCESSORIES SECTIONAccessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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
Connecting Spool Gun Adapter Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-3
Making a Weld with the Spool Gun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-4
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SECTION C
POWER MIG 255C
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C-2
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.
Electrode Type
Solid Steel
(Includes
Stainless
Steel)
Cored
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Aluminum
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C-2
ACCESSORIES
Wire Size
Drive Roll Kit
.023”-.030” (0.6-0.8 mm)
.035” (0.9 mm)
.045” (1.2 mm)
.035-.045 (0.9-1.2mm)
.040 (1.01)
.035” (0.9 mm)
.045” (1.2 mm)
3/64” (1.2 mm)
KP1696-030S
KP1696-035S
KP1696-045S
KP1696-1
KP1696-2
KP1697-035C
KP1697-045C
KP1695-3/64A
3/64" (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" (1.2 mm) aluminum wire. 5356 alloy aluminum wire
is recommended for best push feeding peformance.
Kit includes drive rolls and wire guide plate for the wire drive, liner
and two contact tips for the gun, along with installation instructions.
K2378-1 Canvas Cover
K468 Spindle Adapter - for 8” (203.2mm) O.D.
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:
WARNING
Remove all input power to the POWER MIG 255C
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. Prepare for kit installation by turning the power
switch off and disconnecting power from the
machine.
spool.
3. Remove the lower cover panel from the front of the
machine by removing the two screws which secure
K363P READI-REEL ADAPTER
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The K363P Readi-Reel Adapter mounts to the 2" 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" dia. x
5' 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
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The following Magnum 250L gun and cable assemblies
are separately available for use with the POWER MIG
255C. 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:
English Wire
4. Attach the black rectangular 10-pin plug connector
on the timer kit wiring harness to the black mating
receptacle connector located on the P.C. board. 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 harness
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.
Metric Wire
Length
Part No.
Size1
Size
12' (3.6 m)
15' (4.5 m)
K533-7
K533-3
.035 – .045"
0.9 – 1.2 mm
POWER MIG 255C
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C-3
C-3
ACCESSORIES
OPERATING INSTRUCTIONS FOR TIMER
KIT
If the optional Timer Kit (K1701-1) is installed, select
the desired mode with the selector switch:
A. 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.
B. 4-Step Trigger interlock mode eliminates the need
to hold the gun trigger while welding. It operates in 4
steps:
1. Close trigger and establish welding arc.
2. Release trigger and continue welding.
3. Reclose trigger near end of weld.
4. 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.
Note: 4 Step Trigger interlock mode does not function
with a Spool Gun.
C. Spot Weld Mode is is used for tack welding parts
into position or for spot plug welds to hold thin sheet
metal together prior to manual stitch or continuous
welding. To use this feature, adjust the On-Time (05 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" (5 mm) diameter hole in the top sheet and arc
welding through the hole into the back sheet.
To make spot plug welds, punch 3/16" (5 mm) holes
in the top sheet. Set the Spot Time control to
approximately 1.2 seconds and set the procedure
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.
D. Burnback Time control provides manual
adjustment of the burnback time (0-250
milliseconds) for any selected welding mode. this
control should be set as low as possible without the
wire "sticking" 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.
E. 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 - 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 counter clockwise to "OFF", Run-in speed will
equal the preset WFS on the machine.
SPOOL GUN
Remove all input power to the POWER MIG 255C
before proceeding.
-----------------------------------------------------------------------
WARNING
The POWER MIG 255C provides direct connection
and use of the Spool Gun (with remote speed control).
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.
K2297-2
Prince® XL Spool Gun
K487-25 Magnum® SG Spool Gun (requires K2445-1
Cable Adapter)
K2445-1 Magnum SG Spool gun Control Cable
Adapter
Allows the K487-25 Magnum SG spool gun’s 6-pin control
cable plug to connect to the Power MIG 255C’s 7-pin spool
gun control cable receptacle.
K1738-1 Spool Gun Hanger Accessory
CONNECTING THE SPOOL GUN TO THE
POWER MIG 255C
(See Figure C.1)
1. Connect the Spool Gun control cable to the mating
7-pin receptacle in the Power MIG wire drive
compartment. K487-25 Magnum SG Spool Gun
requires K2445-1 cable 7-pin to 6-pin adapter.
2. Connect the Spool Gun electrode lead to the
(+)positive stud with the Spool Gun electrode lead
sandwiched between the (+)positive power source
electrode lead and the (+)positive stud. Tighten and
be careful not to strip the threads.
3. Attach the Spool Gun gas line to the 5/8 Gas fitting
on the front of the machine.
4. Attach a Gas hose from the Gas supply to the rear
inlet gas fitting on the Power MIG 255C.
POWER MIG 255C
FIGURE C.1
7-PIN
SPOOL GUN
RECEPTACLE
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+
MAKING A WELD WITH
PRINCE XL SPOOL GUN
THE
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K2445-1
CABLE ADAPTER
(7-pin to 6-pin)
Note: This adapter is only
for The Magnum SG
Spool Gun.
+ POSITIVE
CABLE AND STUD
GAS LINE
AND 5/8 FITTING
The POWER MIG control circuitry is designed to
sense either the spool gun or (built in) wire feeder
trigger circuitry. The spool gun can easily be plugged
in and will be ready to use.
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C-4
ACCESSORIES
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C-4
c. Adjusting the wire speed control on the spool
gun will increase or decrease the spool gun wire
feed speed.
d. To aid in set-up, the POWER MIG 255C wire
feed speed(WFS) meter will display the approximate WFS of the gun. Actual WFS at the gun
may vary from the displayed value due to tension setting, liner condition or gun variation.
4. The following procedure settings for Aluminum
4043 can be used as initial settings for making
test welds to determine final settings:
CAUTION
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:
Wire Diameter
In. (mm)
.030” (.8mm)
.035” (.9mm)
3/64” (1.2mm)
Wire Feed Speed Arc voltage
Setting
Display
270
250
240
15V
16V
20V
a. Disables spool gun operation.
b. Closing feeder gun trigger starts feeder gun
welding and makes both electrodes electrically "HOT".
5. To return to normal POWER MIG 255C welding,
release the spool gun trigger and reset feeder gun
voltage procedure setting if necessary.
2. Pulling SPOOL GUN Trigger:
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a. Disables built-in feeder gun operation.
b. Closing spool gun trigger starts spool gun
weld-ing and makes both electrodes electrically
"HOT".
3. Operation with POWER MIG 255C:
a. Turn the POWER MIG 255C input power ON.
b. Adjusting the voltage control will increase or
decrease your welding voltage.
MAKING A WELD WITH
MAGNUM SG SPOOL GUN
THE
The POWER MIG control circuitry is designed to
sense either the spool gun or (built in) wire feeder
trigger circuitry. The spool gun can easily be plugged
in and will be ready to use.
POWER MIG 255C
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C-5
ACCESSORIES
CAUTION
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 electrically "HOT".
2. Pulling SPOOL GUN Trigger:
a. Disables built-in feeder gun operation.
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b. Closing spool gun trigger starts spool gun weld-ing and
makes both electrodes electrically "HOT".
3. Operation with POWER MIG 255C:
a. Turn the POWER MIG 255C input power ON.
b. Adjusting the voltage control will increase or decrease your
welding voltage.
c. Adjusting the wire speed control on the spool gun will
increase or decrease the spool gun wire feed speed.
d. For the Magnum SG Spool Gun, the wire feed speed is
controlled by combination of the wire feed speed displayed
on the POWER MIG 255C and the wire speed control on
the spool gun.
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See the following procedure for setting the Wire Speed Feed
using the Magnum SG Spool Gun:
Wire Feed Speed
Display
SG Spool Gun Wire Feed Speed
Approximate Range
50
300
700
50-200
200-400
300-600
To determine spool gun wire feed speed use a hand tachometer,
or calculate the speed using the following equation:
IPM= Length of wire fed (inches) x 60
Time fed (seconds)
4. To return to normal POWER MIG 255C welding, release the
spool gun trigger and reset feeder gun welding procedures.
POWER MIG 255C
C-5
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C-6
NOTES
POWER MIG 255
C-6
MAINTENANCE
SECTION D
TABLE OF CONTENTS
-MAINTENANCE SECTIONMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section D
Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-2
General Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-2
Drive Rolls and Guide Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-2
Contact Tip & Gas Nozzle Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-2
Gun Tubes and Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-2
Gun Cable Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-2
Liner Removal and Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-2
Liner Removal, Installation, and Trimming Instructions for Magnum 250L . . . . . . . . . . . . . . . . . . .
D-3
Accessories and Expendable Replacement Parts for Magnum 250L Gun and Cable Assemblies .
D-4
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SECTION D
POWER MIG 255C
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D-2
1. Be sure the nozzle insulator is fully screwed onto the
gun tube and does not block the gas holes in the diffuser.
SAFETY PRECAUTIONS
WARNING
• Have a qualified electrician do the
maintenance and troubleshooting
work.
• Disconnect the input power off
using the disconnect switch at the
main input supply before working
inside machine.
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• Unplug the power cable if it is connected to a
receptacle.
------------------------------------------------------------------------
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In extremely dusty locations, dirt may clog the air
passages causing the welder to run hot. Blow dirt out
of the welder with low-pressure air at regular intervals
to eliminate excessive dirt and dust build-up on internal
parts.
The fan motors have sealed ball bearings which
require no service.
After every coil of wire, inspect the wire drive
mechanism. Clean it as necessary by blowing with low
pressure compressed air. Do not use solvents for
cleaning the idle roll because it may wash the lubricant
out of the bearing.
GUN TUBES AND NOZZLES
b. Remove spatter from inside of gas noz-zle and from
tip after each 10 minutes of arc time or as required.
GUN CABLE CLEANING
To help prevent feeding problems, clean cable liner
after using approximately 300 pounds (136 kg) of electrode. Remove the cable from the wire feeder and lay
it out straight on the floor. Remove the contact tip from
the gun. Using an air hose and only partial pressure,
gently blow out the cable liner from the gas diffuser
end.
CAUTION
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.
Excessive pressure at the start may cause the dirt
to form a plug.
For instructions on replacing or changing drive roll, see
"Wire Drive Rolls" in Operation section.
Flex the cable over its entire length and again blow out
the cable. Repeat this procedure until no further dirt
comes out. If this has been done and feed problems
are experienced, try liner replacement, and refer to
trouble shooting section on rough wire feeding.
CONTACT TIP
INSTALLATION
AND
GAS
NOZZLE
LINER REMOVAL AND REPLACEMENT
a. Choose the correct size contact tip for the electrode
being used (wire size is stenciled on the side of the
contact tip) and screw it snugly into the gas diffuser.
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2. Slip the appropriate gas nozzle onto the nozzle insulator. Either a standard .50" (12.7 mm) or optional
.62" (15.9 mm) I.D. slip-on gas nozzle may be used
and should be selected based on the welding application.
Adjust the gas nozzle as appropriate for the
GMAW process to be used. Typically, the contact tip end should be flush to .12" (3.2 mm)
extended for the short-circuiting transfer process
and .12" (3.2 mm) recessed for spray transfer.
a. Replace worn contact tips as required.
GENERAL MAINTENANCE
DRIVE ROLLS AND GUIDE PLATES
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D-2
MAINTENANCE
NOTE: Changing the liner for a different wire size
requires replacement of the gas diffuser per Table D.1
to properly secure the different liner.
b. Screw the appropriate fixed gas nozzle fully onto the
diffuser. Either the standard .50" (12.7 mm) flush
nozzle or other optional flush or recessed (spray arc)
nozzle sizes may be used. (See Table D.2 in this
section.)
c. If using optional adjustable slip-on noz-zles, see
Table D.2 in this section.
POWER MIG 255C
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D-3
D-3
MAINTENANCE
6.
TABLE D.1
Diámetro de
Diameter
of
Electrodos
Utilizados
Electrode
Used
.025-.030" Steel
Replace
Size
mentde Tamaño
Stencilled
on
Número
Grabado
Line
End of liner
Parte de la en el extremo del
Part
Bushing
Guía
Cilindro de la Guía
Number
No. de Parte
Adjustable
nozzle
Gas
No. de Parte
del
del Difusor
de
Fixed
Nozzle
Diffuser
Gas
Diffuser
Difusor
de Gas
Gas de la
Part
No.
Part
No. (and
de la Tobera Fija Tobera
ajustable
(and
stencil)
(grabado)
(grabado)
Stencil)
KP1934-2
.030 (0.8 mm)
KP2026-3
KP2026-2
KP1934-1
.045 (1.2 mm)
KP2026-3
KP2026-1B1
KP1955-1
3/64" (1.2 mm)
KP2026-3
KP2026-1B1
7.
(0.6-0.8 mm)
.035-.045" Steel
(0.9-1.2 mm)
3/64" Aluminum
8.
With the gas diffuser still removed from the gun
tube, be sure the cable is straight, and then trim
the liner to the length shown in Figure D.1.
Remove any burrs from the end of the liner.
Screw the gas diffuser onto the end of the gun
tube and securely tighten. Be sure the gas diffuser
is correct for the liner being used. (See table and
diffuser stencil.)
Tighten the set screw in the side of the gas diffuser
against the cable liner using a 5/64" (2.0 mm) Allen
wrench.
(1.2 mm)
LINER REMOVAL, INSTALLATION
AND TRIMMING INSTRUCTIONS FOR
MAGNUM 250L
FIGURE D.1
TORNILLO
DE FIJACION
SET SCREW
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BRASS CABLE
CONECTOR
DECONNECTOR
CABLE DE COBRE
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
cutoff length requirement. Liners are shipped
with the
jacket of the liner extended the proper amount.
Return to Master TOC
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1. Remove the gas nozzle and nozzle insulator, if used, to locate the set screw in the gas
diffuser which is used to hold the old liner in
place. Loosen the set screw with a 5/64"
(2.0 mm) Allen wrench.
2. Remove the gas diffuser from the gun tube.
3. Lay the gun and cable out straight on a flat
surface. Loosen the set screw located in the
brass connector at the feeder end of the
cable and pull the liner out of the cable.
4.
Insert a new untrimmed liner into the connector end of the cable. Be sure the liner
bushing is stencilled appropriately for the
wire size being used.
Note: For liners KP1950-7,
KP1955-1 and KP1599-2
TORNILLO DE
FIJACION
SET
SCREW
DIFUSOR
DE GAS
GAS DIFFUSER
AISLADOR
DE TOBERA
NOZZLE
INSULATOR
(IF USED)
(SI SE UTILIZA)
GAS NOZZLE
TOBERA
DE GAS
WARNING
This screw should only be gently tightened.
Overtightening will split or collapse the liner and cause
poor wire feeding.
-----------------------------------------------------------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, turn the
collars approximately 60 degrees counterclockwise (the same
direction as removing a right hand thread) until the collar
reaches a stop. Then pull the collar off the gun handle. 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.
KP1950-8,
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counterclockwise
Before fully seating the liner bushing, it will be
necessary to trim the liner’s inner tube flush with
the liner bushing using a sharp blade. After trimming, remove any burrs from inner tube and
insure that the opening is fully open.
5.
1-1/4"
(31.8mm)
1-1/4
(31,8 mm)
LONGITUD
DE
LINER
TRIM
CORTE
LENGTH
Fully seat the liner bushing into the connector. tighten the set screw on the brass cable
connector. The gas diffuser, at this time,
should not be installed onto the end of the
gun tube.
POWER MIG 255C
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D-4
TABLE D.2
ACCESSORIES AND EXPENDABLE REPLACEMENT PARTS FOR MAGNUM 250L GUN AND
CABLE ASSEMBLIES
Description
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CONTACTS TIPS
Standard Duty
Heavy Duty
Tapered
Notched (For Alum.)
GAS NOZZLES
Fixed (Flush)
Fixed (Recessed)
Requires: Gas
Diffuser as’bly
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Adjustable Slip On
English
Size
Metric
Size
KP1934-2
KP1934-1
KP1955-1
.025 – .030"
.035 – .045"
3/64"
(Alum. wire)
0.6 – 0.8 mm
0.9 – 1.2 mm
1.2 mm
(Alum. wire)
KP2020-6B1
KP2020-7B1
KP2020-1B1*
KP2020-2B1*
KP2021-1B1
KP2021-2B1
KP2021-5B1
KP2021-6B1
KP2022-1B1
KP2022-2B1
KP2010-5B1
.025"
.030"
.035"
.045"
.035"
.045"
.025"
.030"
.035"
.045"
3/64"
(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.)
KP1931-1
KP1931-2*
KP1931-3
KP1930-1
KP1930-2
KP1930-3
3/8"
1/2"
5/8"
3/8"
1/2"
5/8"
9.5 mm
12.7 mm
15.9 mm
9.5 mm
12.7 mm
15.9 mm
KP2026-3 *
.025 – .045"
0.6 – 1.2 mm
KP1935-2
KP1935-1
1/2"
5/8"
12.7 mm
15.9 mm
.025 – .030"
.035 – .045"
0.6 – 0.8 mm
0.9 – 1.2 mm
Part No.
CABLE LINER
For 15'
(4.5 m) or
shorter cable
Requires:
Nozzle Insulator
KP2025-1
Requires:
Gas diffuser
As’bly
KP2026-2
KP2026-1
Gasless nozzle
(For Innershield)
GUN TUBE ASSEMBLIES
Standard (60°)
45°
KP1947-1∆
KP2015-1 *
KP2041-1
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*Included with POWER MIG 255C
Requires KP2026-1 Gas Diffuser
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D-4
MAINTENANCE
POWER MIG 255C
SECTION E
THEORY OF OPERATION
TABLE OF CONTENTS
-THEORY OF OPERATION SECTION-
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
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SECTION E
FIGURE E.1 — BLOCK LOGIC DIAGRAM.
GAS
SOLENOID
FAN
MOTOR
SPOOL
GUN
WIRE
DRIVE
MOTOR
WIRE
SPEED
ARC
VOLTAGE
CONTROL
BOARD
TACH
AUX
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115 VAC
GUN TRIGGER
RECTIFIER
DIODE
BRIDGE
G
A
T
E
30 VAC
SNUBBER
BOARD
LINE
SWITCH
S
I
G
N
A
L
POWER
ENHANCEMENT
CHOKE
RECONNECT
MAIN
TRANSFORMER
SCR
RECTIFIER
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FEEDBACK
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
K
OUTPUT
CHOKE
SHUNT
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
POWER MIG 255C
POSITIVE
TERMINAL
NEGATIVE
TERMINAL
FIGURE E.2 — INPUT LINE VOLTAGE AND MAIN TRANSFORMER.
GAS
SOLENOID
FAN
MOTOR
SPOOL
GUN
WIRE
DRIVE
MOTOR
WIRE
SPEED
CONTROL
BOARD
ARC
VOLTAGE
TACH
AUX
115 VAC
RECTIFIER
DIODE
BRIDGE
30 VAC
SNUBBER
BOARD
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LINE
SWITCH
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E-2
THEORY OF OPERATION
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E-2
GUN TRIGGER
G
A
T
E
FEEDBACK
S
I
G
N
A
L
POWER
ENHANCEMENT
CHOKE
RECONNECT
MAIN
TRANSFORMER
SCR
RECTIFIER
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
K
OUTPUT
CHOKE
POSITIVE
TERMINAL
NEGATIVE
TERMINAL
SHUNT
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INPUT LINE VOLTAGE
AND MAIN TRANSFORMER
The desired single phase input power is connected to
the POWER MIG 255C through a line switch located
on the front panel.
A reconnect 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 transformer. 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
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 rectified 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
supplies power, through the control board, to the thermostatically controlled fan motor and also provides
voltage for the auxiliary receptacle
The fan is designed to come on automatically when
weld arc is established. The fan will stay on for a minimum 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-temperature protection. (See Thermal and Overload
Protection.)
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
POWER MIG 255C
FIGURE E.3 — OUTPUT RECTIFICATION AND FEEDBACK.
GAS
SOLENOID
FAN
MOTOR
SPOOL
GUN
WIRE
DRIVE
MOTOR
WIRE
SPEED
CONTROL
BOARD
ARC
VOLTAGE
TACH
AUX
115 VAC
RECTIFIER
DIODE
BRIDGE
30 VAC
SNUBBER
BOARD
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LINE
SWITCH
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E-3
THEORY OF OPERATION
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E-3
GUN TRIGGER
G
A
T
E
FEEDBACK
S
I
G
N
A
L
POWER
ENHANCEMENT
CHOKE
RECONNECT
MAIN
TRANSFORMER
SCR
RECTIFIER
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
K
OUTPUT
CHOKE
POSITIVE
TERMINAL
NEGATIVE
TERMINAL
SHUNT
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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
the commands of the ARC Voltage Control potentiometer 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, the wire drive motor, and spool
gun receptacle.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
POWER MIG 255C
FIGURE E.4 — CONSTANT VOLTAGE OUTPUT.
GAS
SOLENOID
FAN
MOTOR
SPOOL
GUN
WIRE
DRIVE
MOTOR
WIRE
SPEED
CONTROL
BOARD
ARC
VOLTAGE
TACH
AUX
115 VAC
RECTIFIER
DIODE
BRIDGE
30 VAC
SNUBBER
BOARD
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LINE
SWITCH
Return to Section TOC
E-4
THEORY OF OPERATION
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E-4
GUN TRIGGER
G
A
T
E
FEEDBACK
S
I
G
N
A
L
POWER
ENHANCEMENT
CHOKE
RECONNECT
MAIN
TRANSFORMER
SCR
RECTIFIER
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
K
OUTPUT
CHOKE
POSITIVE
TERMINAL
NEGATIVE
TERMINAL
SHUNT
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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
power factor enhancement choke is filtered by the
capacitor bank resulting in a constant voltage DC output. Since the output choke is in series with the positive 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.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
POWER MIG 255C
FIGURE E.5 — WIRE DRIVE MOTOR AND FEEDBACK.
GAS
SOLENOID
FAN
MOTOR
SPOOL
GUN
WIRE
DRIVE
MOTOR
WIRE
SPEED
CONTROL
BOARD
ARC
VOLTAGE
TACH
AUX
115 VAC
RECTIFIER
DIODE
BRIDGE
30 VAC
SNUBBER
BOARD
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LINE
SWITCH
Return to Section TOC
E-5
THEORY OF OPERATION
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E-5
GUN TRIGGER
G
A
T
E
FEEDBACK
S
I
G
N
A
L
POWER
ENHANCEMENT
CHOKE
RECONNECT
MAIN
TRANSFORMER
SCR
RECTIFIER
C
A
P
A
C
I
T
O
R
S
F
E
E
D
B
A
C
K
OUTPUT
CHOKE
POSITIVE
TERMINAL
NEGATIVE
TERMINAL
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SHUNT
WIRE DRIVE MOTOR
AND FEEDBACK
the wire drive motor. The drive motor speed is thus
controlled which in turn regulates the electrode wire
feed speed through the gun.
The wire drive motor is controlled by the control board.
A motor speed feedback signal is generated at the
motor tach and sent to the control board. The control
board compares this feedback signal with the commands set forth by the Wire Speed Control potentiometer and sends the appropriate armature voltage to
The control board also provides a 3-24 VDC operating
voltage for the optional spool gun. To achieve full WFS
control at the spool gun, the WFS knob on front of the
PM-255C must be set at max.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
POWER MIG 255C
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E-6
THEORY OF OPERATION
E-6
OVERCURRENT PROTECTION
THERMAL AND OVERLOAD
PROTECTION
The POWER MIG 255C has built-in protective thermostats 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 operating 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.
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 temperature 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 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.
POWER MIG 255C
THEORY OF OPERATION
E-7
FIGURE E.6 — SCR OPERATION.
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E-7
INPUT
CATHODE
OUTPUT
NOTE: AS THE GATE
PULSE IS APPLIED
LATER IN THE CYCLE
THE SCR OUTPUT
IS DECREASED.
ANODE
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GATE
SCR OPERATION
A silicon controlled rectifier (SCR) is a three terminal
device used to control rather large currents to a load.
An SCR acts very much like a switch. 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 supply. 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 controlled 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 cathode 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.
POWER MIG 255C
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E-8
NOTES
POWER MIG 255C
E-8
TROUBLESHOOTING AND REPAIR
F-1
TABLE OF CONTENTS
-TROUBLESHOOTING AND REPAIR SECTIONTroubleshooting and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section F
How to Use Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F-2
PC Board Troubleshooting Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F-3
Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F-4
Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F-11
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
Component Replacement Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F-37
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
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F-1
POWER MIG 255C
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F-2
TROUBLESHOOTING AND REPAIR
HOW TO USE TROUBLESHOOTING GUIDE
WARNING
Service and Repair should only be performed by 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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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 the following
categories: output problems, function problems, wire 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. RECOMMENDED
COURSE OF ACTION
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 specified 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
tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
---------------------------------------------------------------------------------------------------------------------------
POWER MIG 255C
F-2
TROUBLESHOOTING & REPAIR
WARNING
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.
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CAUTION
Sometimes machine failures appear to be due to PC
board failures. These problems can sometimes be
traced to poor electrical connections. To avoid problems 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.
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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:
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F-3
PC BOARD TROUBLESHOOTING PROCEDURES
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F-3
PC board can be damaged by static electricity.
ATTENTION
Static-Sensitive
Devices
Handle only at
Static-Safe
Workstations
- Remove your body’s static
charge before opening the staticshielding 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.
- 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-shielding 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 proper 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.
- Tools which come in contact with the PC board must
be either conductive, anti-static or static-dissipative.
POWER MIG 255C
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F-4
TROUBLESHOOTING AND REPAIR
F-4
TROUBLESHOOTING GUIDE
Observe all Safety Guidelines detailed throughout this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
OUTPUT PROBLEMS
Major Physical or Electrical Damage 1. Contact your local Lincoln 1. Contact The Lincoln Electric
is Evident
Electric Authorized Field Service
Service Dept. 1-888-935-3877
Facility.
1. Check input power switch (S1).
Machine is dead — no open circuit 1. Make certain that the input
It may be faulty.
voltage output and no wire feed
power switch is in the "ON" posiwhen gun trigger is pulled. The
tion.
2. Check for lose or broken wires
machine display may be lit.
at the reconnect panel.
2. Check the input voltage at the
machine. Input voltage must 3. Perform Main Transformer
match the rating plate and the
Test.
reconnect panel.
4. Perform Rectifier Diode Bridge
3. Blown or missing fuses in the
Test.
input line.
5. Check the thermostats and
4. The thermostats may be open
associated leads for loose or
due to machine overheating. If
broken connections. See wiring
machine operates normally after
diagram.
a cooling off period then check
for proper fan operation and 6. The control board may be faulty.
ventilation. Make certain that the
Replace.
machine's duty cycle is not
being exceeded.
5. Check the trigger circuit. Leads
#324 to #325 should have continuity (zero ohms) when the gun
trigger is pulled. If not then the
gun may be faulty — replace.
6.
Make sure the machine is not
connected to a portable generator.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-----------------------------------------------------------------------------------------------------------------------------------------------------POWER MIG 255C
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F-5
F-5
TROUBLESHOOTING AND REPAIR
Observe all Safety Guidelines detailed throughout this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
OUTPUT PROBLEMS (Continued)
No open circuit voltage output but 1. Check the input voltage at the 1. Check for loose or broken conwire feeds normally when gun trigmachine. Input voltage must
nections at the output terminals,
ger is pulled.
match the rating plate and the
the chokes, the capacitor bank
reconnect panel.
and all heavy current carrying
leads. See Wiring Diagram.
2. The gun may be faulty. Check
or replace.
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
Test.
Main
Transformer
5. The control board may be faulty.
Replace.
Wire feeds but welding output is low 1. Make sure that the proper wire 1. Check for loose or faulty connections of the heavy current
causing wire to “stub”. Welds are
and procedures are being used.
carrying leads.
“cold”. Machine cannot obtain full
rated output of 200 amps at 28 volts. 2. Check gun and work cable for
2. The output capacitor bank may
loose or faulty connections.
be faulty. Check for loose connections at the capacitors. Also
check for leaky capacitors.
Replace if necessary.
WARNING: The liquid electrolyte in these capacitors is
toxic. Avoid contact with any
portion of your body.
3. Perform the SCR Rectifier
Assembly Tests.
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4. Perform the Main Transformer
Test.
5. The control board may be faulty.
Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-----------------------------------------------------------------------------------------------------------------------------------------------------POWER MIG 255C
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F-6
TROUBLESHOOTING AND REPAIR
F-6
Observe all Safety Guidelines detailed throughout this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
OUTPUT PROBLEMS (Continued)
The output voltage and wire feed is 1. Remove the gun. If the problem 1. Check the machine's internal
present continuously or pulsing
is resolved the gun trigger circuit
trigger leads for grounds or
when gun trigger is NOT activated.
is faulty. Repair or replace.
shorts. See Wiring Diagram.
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2. If problem persists when gun 2. The control board may be faulty.
assembly is removed from
Replace.
machine, then the problem is
within the POWER MIG 255C.
The output voltage is present contin- Contact your local Lincoln Electric
uously when gun trigger is NOT acti- Authorized Field Service Facility.
vated.
1. Perform the SCR Rectifier
Assembly Tests.
2. The control board may be faulty.
Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-----------------------------------------------------------------------------------------------------------------------------------------------------POWER MIG 255C
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F-7
TROUBLESHOOTING AND REPAIR
F-7
Observe all Safety Guidelines detailed throughout this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
FUNCTION PROBLEMS
No control of arc voltage. Wire feed- 1. The arc voltage control poten- 1. The arc voltage control potening is normal.
tiometer may be dirty. Rotate
tiometer may be faulty. Check or
several times and check if probreplace. See Wiring Diagram.
lem is resolved.
2. Perform the SCR Rectifier
Assembly Tests.
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3. The control board may be faulty.
Replace.
There is no gas flow when gun trig- 1. Check gas source and hoses for 1. Check the gas solenoid by disger is pulled. Wire feeds and weld
leaks or kinks.
connecting it from the control
voltage is present.
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.
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2. The control broad may be faulty.
Replace.
The machine stops feeding wire 1. Check for adequate wire supply. 1. Check the motor armature current. Normal armature current is
while welding.
2. Check for mechanical restric2.0 to 2.7 amps maximum. If
tions in the wire feeding path.
the motor armature current is
normal the control board may be
The gun may be clogged.
faulty. Replace.
3. Check gun liner and tip are cor2. If the motor armature current is
rect for wire size being used.
high (over 2.7 amps) and there
4. Check spindle for ease of rotaare NO restrictions in the wire
tion.
feeding path then the motor or
gear box may be defective.
5. If Timer Option Kit is installed,
Replace.
make sure spot timer knob is
set to OFF.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-----------------------------------------------------------------------------------------------------------------------------------------------------POWER MIG 255C
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F-8
TROUBLESHOOTING AND REPAIR
F-8
Observe all Safety Guidelines detailed throughout this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
WIRE FEEDING PROBLEMS
No control of wire feed speed. Other 1. The wire feed speed control 1. The Wire Speed Control potenmachine functions are normal
may be dirty. Rotate several
tiometer may be faulty. Check or
times and check if problem is
replace. See Wiring Diagram.
resolved.
2. Perform the Wire Drive Motor
and Tachometer Feedback
Test.
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3. The control board may be faulty.
Replace.
There is no wire feed when gun trig- 1. Check for adequate wire supply. 1. Perform the Wire Drive Motor
ger is pulled. Normal open circuit
and Tachometer Feedback
voltage is present.
2. If the drive rolls are turning then
Test.
check for a mechanical restric2. The Wire Feed Control potention in the wire feed path.
tiometer may be faulty. Check or
replace. See Wiring Diagram.
3. The gun liner may be clogged.
Check or replace.
3. The control board may be faulty.
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.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-----------------------------------------------------------------------------------------------------------------------------------------------------POWER MIG 255C
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F-9
TROUBLESHOOTING AND REPAIR
F-9
Observe all Safety Guidelines detailed throughout this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
WELDING PROBLEMS
The arc is unstable and or “hunting”. 1. Check for worn or melted con- 1. Check for loose connections at
tact tip.
the output terminals, the
chokes, the capacitor bank and
2. Check for loose or faulty conall heavy current carrying leads.
nections on the work and elecSee Wiring Diagram.
trode cables.
2. Make sure that the transformer
3. Make sure electrode polarity or
secondary leads are securely
welding process being used, is
connected to the SCR rectifier
correct.
assembly.
4. Check for rusty or dirty wire.
3. The output capacitor bank may
be faulty. Check for loose con5. Make sure machine settings and
nections at the capacitors. Also
gas are correct for process
check for leaky capacitors.
being used.
Replace if necessary.
WARNING: The liquid electrolyte in these capacitors is
toxic. Avoid contact with any
portion of your body.
4. Perform the SCR Rectifier
Assembly Tests.
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5. The control board may be faulty.
Replace.
Weld bead is narrow or ropy. May 1. Make sure the weld procedure 1. The output capacitor bank may
have porosity with electrode stuband electrode polarity is correct
be faulty. Check for loose conbing into plate.
for the process being used.
nections at the capacitors. Also
check for leaky capacitors.
2. Make sure shielding gas is corReplace if necessary.
rect and flow is proper.
WARNING: The liquid elec3. Make sure the weld joint is not
trolyte in these capacitors is
“contaminated”.
toxic. Avoid contact with any
portion of your body.
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2. The control board may be faulty.
Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-----------------------------------------------------------------------------------------------------------------------------------------------------POWER MIG 255C
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F-10
TROUBLESHOOTING AND REPAIR
F-10
Observe all Safety Guidelines detailed throughout this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
WELDING PROBLEMS (Continued)
The contact tip seizes in the gas
diffuser.
1. The tip being over heated due to 1. Make sure tip is tight in diffuser.
excessive current and/or high
duty cycle welding.
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2. A light application of high temperature anti-sieze lubricant
(such as Lincoln E2607
Graphite Grease) may be
applied to the contact tip
threads.
The welding arc is variable and
sluggish.
1. Check the welding cable con- 1. Perform the SCR Rectifier
nections for loose or faulty conAssembly Tests.
nections.
2. The control board may be faulty.
2. Make sure the wire feed speed,
Replace.
voltage, and shielding gas are
correct for the process being
used.
The arc striking is poor.
1. Check the welding cable con- 1. The output capacitor bank may
nections for loose or faulty conbe faulty. Check for loose connections.
nections at the capacitors. Also
check for leaky capacitors.
2. Make sure the wire feed speed,
Replace if necessary.
voltage, and shielding gas are
correct for the process being
WARNING: The liquid elecused.
trolyte in these capacitors is
toxic. Avoid contact with any
portion of your body.
2. The control board may be faulty.
Replace.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-----------------------------------------------------------------------------------------------------------------------------------------------------POWER MIG 255C
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F-11
TROUBLESHOOTING AND REPAIR
TEST PROCEDURES
MAIN TRANSFORMER TEST
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
Return to Master TOC
Return to Section TOC
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
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 primary windings of the main transformer.
b. Induced on the secondary and auxiliary windings of the main transformer.
MATERIALS NEEDED
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3/8 in. Nutdriver
5/16 in. Nutdriver
Volt-ohmmeter
POWER MIG 255C
F-11
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F-12
F-12
TROUBLESHOOTING AND REPAIR
MAIN TRANSFORMER TEST (continued)
FIGURE F.1 — G3521 CONTROL PC BOARD AND M19248 SNUBBER PC BOARD
MAIN TRANSFORMER TEST POINTS.
X5
(6J6)
J5
#208
(2J5)
X6
(5J6)
X7
(4J6)
X9
(8J5)
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J6
#206
(3J5)
X8
(16J5)
#209
(1J5)
J3
J8
J1
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J4
J2
4. Locate plug J6 on the control PC board.
See Figure F.1.
TEST PROCEDURE
WARNING
The ON/OFF POWER SWITCH will be
“hot” during these tests.
----------------------------------------------------------
NOTE: The location of plugs may vary
depending on the machine code.
5. Locate the following leads on plug J6
on the control PC board:
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NOTE: Secondary voltages will vary proportionately with the primary input voltage.
1. Disconnect the main input power supply to the machine.
LEAD
PLUG
LOCATION
2. Remove the case top and side panels
with a 3/8 in. nutdriver.
X5
X6
X7
6J6
5J6
4J6
3. Remove the tool tray with a 5/16 in. nutdriver.
POWER MIG 255C
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F-13
MAIN TRANSFORMER TEST (continued)
6. Connect main input power to the
machine.
7. Turn the POWER MIG 255C ON/OFF
POWER SWITCH to ON.
8. Carefully make the following voltage
tests at plug J6.
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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.
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
X5
(6J6)
X6
(5J6)
15VAC
X5
(6J6)
X7
(4J6)
30VAC
X6
(5J6)
X7
(4J6)
15VAC
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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.
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
X8
(16J5)
X9
(8J5)
115VAC
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.
9. Turn OFF the machine.
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F-13
TROUBLESHOOTING AND REPAIR
10. Locate the following leads on plug J5
on the Control PC board. See Figure
F.1.
LEAD
PLUG
LOCATION
X8
X9
16J5
8J5
POWER MIG 255C
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TROUBLESHOOTING AND REPAIR
F-14
MAIN TRANSFORMER TEST (continued)
14. Locate the following leads on plug J5
on the Control PC board. See Figure
F.1.
LEAD
PLUG
LOCATION
206
3J5
LEAD
PLUG
LOCATION
208
209
2J5
1J5
d. If ALL the voltages tested are incorrect 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.
15.
Turn the machine ON.
16. Make the following voltage tests at plug
J5 on the 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.
c. If any of the voltages tested are
incorrect, check for loose or broken
leads between the test points and
the main transformer.
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
208
(2J5)
209
(1J5)
56VAC
208
(2J5)
206
28VAC
209
(1J5)
206
28VAC
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F-14
POWER MIG 255C
-test the ON/OFF POWER
SWITCH for proper operation.
b. If the correct nameplate voltage is
being applied to the main transformer and one or more of the secondary voltages are missing or are
incorrect, the main transformer may
be faulty. Replace.
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F-15
TROUBLESHOOTING AND REPAIR
RECTIFIER DIODE BRIDGE TEST
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
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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
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3/8 in. Nutdriver
Volt-ohmmeter
POWER MIG 255C wiring diagrams (See Electrical Diagrams Section of this Manual)
POWER MIG 255C
F-15
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F-16
RECTIFIER DIODE BRIDGE TESTING (continued)
FIGURE F.2 — G3521 RECTIFIER DIODE BRIDGE LOCATION.
RECTIFIER
DIODE BRIDGE
(D2)
TEST PROCEDURE
LEAD
1. Disconnect the main AC input power to
the machine.
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2. Remove the case top and side panels
with a 3/8 in. nutdriver.
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F-16
TROUBLESHOOTING AND REPAIR
3. Perform the Main Transformer Test to
ensure the proper voltages are supplied
to the J5 plug on the Control board.
4. Locate the following leads:
208
209
354
206
Leads #208, #209, 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.
POWER MIG 255C
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F-17
RECTIFIER DIODE BRIDGE TESTING (continued)
6. Turn the POWER MIG 255C ON/OFF
POWER SWITCH to ON.
7. Carefully make the following voltage
tests:
a. Turn the machine OFF between
each test.
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b. Carefully connect the meter plugs
to the exposed lead connections.
c. Turn the machine ON to conduct
the voltage test at J5 connector
Control board
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
208
206
28 VAC
209
206
28 VAC
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8. If any of the AC voltages tested are
incorrect or missing, check the leads
and connections. See the wiring diagram.
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F-17
TROUBLESHOOTING AND REPAIR
POWER MIG 255C
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.
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
354
206
36 VDC
10. If the DC voltage tested is incorrect or
missing, and the AC voltages are correct, the rectifier diode bridge may be
faulty.
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F-18
NOTES
POWER MIG 255C
F-18
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F-19
TROUBLESHOOTING AND REPAIR
STATIC SCR RECTIFIER ASSEMBLY TEST
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
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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 255C 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
POWER MIG 255C
F-19
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F-20
TROUBLESHOOTING AND REPAIR
F-20
STATIC SCR RECTIFIER ASSEMBLY TEST (continued)
FIGURE F.3 — REMOVE PLUGS J6 AND J5 TO PERFORM STATIC RECTIFIER ASSEMBLY TEST.
J6
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J5
J3
J8
J1
J4
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J2
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.
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3. Remove the tool tray with a 5/16 in. nutdriver.
POWER MIG 255C
4. Verify that the capacitors have
completely discharged with a voltohmmeter.
5. Disconnect plugs J6 and J5 from the
control board . This electrically isolates
the SCR bridge assembly. See Figure
F.3.
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F-21
TROUBLESHOOTING AND REPAIR
STATIC SCR RECTIFIER ASSEMBLY TEST (continued)
FIGURE F.4 — LOCATION OF
LEADS X2 AND X3.
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FIGURE F.5 — SCR 1 TEST POINTS.
NEGATIVE
CAPACITOR
BANK BUSS
BAR
LEADS X2 AND X3
CONNECTION
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.
6. Disconnect leads X2 and X3 (braided
copper strap) from the negative capacitor bank buss bar using a 1/2 in. open
end wrench. See Figure F.4.
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F-21
7. Separate leads X2 and X3 from the
negative capacitor bank buss bar. Be
sure there is no electrical contact.
a. If a high or infinite resistance is indicated 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.
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.
POWER MIG 255C
11. Reconnect leads X2 and X3 (braided
copper strap).
12. Reconnect plugs J5 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.
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F-22
NOTES
POWER MIG 255C
F-22
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F-23
TROUBLESHOOTING AND REPAIR
ACTIVE SCR RECTIFIER ASSEMBLY TEST
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
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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
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3/8 in. Nutdriver
5/16 in. Nutdriver
An SCR Tester as specified in this procedure
POWER MIG 255C wiring diagrams (See Electrical Diagrams Section of this Manual)
SCR Heat Sink Assembly Drawings
A volt-ohmmeter
POWER MIG 255C
F-23
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F-24
TROUBLESHOOTING AND REPAIR
F-24
ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued)
FIGURE F.6 — CONTROL BOARD MOLEX PLUG LOCATIONS FOR G3521 PC CONTROL BOARD.
J6
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J5
J3
J8
J1
J4
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J2
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.
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3. Remove the tool tray with a 5/16 in. nutdriver.
POWER MIG 255C
4.Verify that the capacitors have completely
discharged with a volt-ohmmeter.
5. Disconnect plugs J6 and J5 control
board. This electrically isolates the
SCR bridge assembly. See Figure F.6.
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F-25
TROUBLESHOOTING AND REPAIR
ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued)
6. Disconnect leads X2 and X3 (braided
copper strap) from the negative capacitor bank buss bar using a 1/2 in. open
end wrench. See Figure F.7.
FIGURE F.7 — LOCATION OF
LEADS X2 AND X3.
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8. Use a commercial SCR tester or construct 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.
NEGATIVE
CAPACITOR
BANK BUSS
BAR
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F-25
FIGURE F.8 — SCR TESTER CIRCUIT
AND SCR CONNECTIONS.
LEADS X2 AND X3
CONNECTION
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.
POWER MIG 255C
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F-26
ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued)
9. Connect the tester to the SCR 1 as
shown in Figure F.8.
15. Reconnect the tester leads.
Figure F.8.
a. Connect tester lead (A) to the
cathode.
b. Connect tester lead (C) to the
cathode.
b. Connect tester lead (C) to the
anode.
c. Connect tester lead (G) to the gate.
c. Disconnect test lead (G) from the
gate.
16. Close switch SW-1.
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NOTE: Switch SW-2 should be open.
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See
a. Connect tester lead (A) to the
anode.
10. Close switch SW-1.
17. Read meter for zero voltage.
11. Read meter for zero voltage.
a. If the voltage is zero, the SCR is
functioning.
a. If the voltage reading is higher than
zero, the SCR is shorted.
b. If the voltage 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.
18. Perform the Active Test Procedure outlined in Steps 6-15 for SCR 2.
a. If the voltage is 3 to 6 volts while
the switch is closed and after the
switch is open, the SCR is
functioning.
19. Replace all SCR assemblies that do not
pass the above tests.
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 properly. A low battery can affect the results of
the test. Repeat Battery Test Procedure in
Step 6 if needed.
20. Reconnect plug J6 onto the control PC
board and J9 to the snubber PC board.
21. Reconnect leads X2 and X3 to the negative capacitor bank bus bar.
22. Replace the tool tray and case sides.
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14. Open switch SW-1.
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F-26
TROUBLESHOOTING AND REPAIR
POWER MIG 255C
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F-27
TROUBLESHOOTING AND REPAIR
WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
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TEST DESCRIPTION
This test will determine if the wire drive motor and voltage feedback circuit are functioning properly.
MATERIALS NEEDED
5/16 in. Nutdriver
Volt-Ohmmeter
POWER MIG 255C
F-27
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F-28
F-28
TROUBLESHOOTING AND REPAIR
WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued)
FIGURE F.9 — PLUG J1 LOCATION ON CONTROL PC BOARD.
J6
J6
J3J3
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J5
J5
B B J8J8
(4J1)
(4J1)
J1
W W J1
(2J1)
(2J1)
#206B
#206B
(1J1)
(1J1)
#555
#555
(6J1)
(6J1)
#515B
#515B
(5J1)
(5J1)
J4J4
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J2J2
3. Locate plug J1 on the control PC board.
See Figure F.9.
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.
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2. Open the side panels and remove the
tool tray using a 5/16 in. nutdriver.
POWER MIG 255C
4. Locate the following leads on plug J1:
LEAD
PLUG
LOCATION
B
W
4J1
2J1
5. Connect the main power to the
machine.
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F-29
WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued)
6. Make the following voltage tests:
a. Turn the machine OFF between
each test.
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2. Locate plug J1 on the control PC board.
See Figure F.9.
3. Locate the following leads on Plug J1:
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.
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
B
(4J1)
W
(2J1)
3-20 VDC
(varies depending on wire feed
speed)
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 connector J12 for proper connection and contact.
8. If all wires and connectors are good and
the voltage to the drive motor armature
is zero, the 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
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1. Disconnect the main AC input power to
the machine.
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F-29
TROUBLESHOOTING AND REPAIR
POWER MIG 255C
LEAD
PLUG
LOCATION
515B
206B
5J1
1J1
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.
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
515B
(5J1)
206B
(1J1)
15 VDC
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.
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F-30
WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued)
TEST FOR FEEDBACK VOLTAGE
TO CONTROL BOARD
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
2. Locate plug J1 on the control PC board.
555
(6J1)
206B
(1J1)
1.5 to 3.5 VDC
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LEAD
PLUG
LOCATION
555
206B
6J1
1J1
4. Connect main input power to the
machine.
5. Make the following voltage tests:
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6. If the 1.5 to 3.5 VDC is present, the
tachometer circuit is sending the correct 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.
a. Turn the machine OFF between
each test.
8. If the leads are okay, the tachometer
circuit may be faulty, replace the
tachometer circuit.
b. Carefully insert the meter probes
into the back of each Molex plug
pin cavity.
9. Replace the tool tray.
c. Turn the machine ON and pull the
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gun trigger to conduct the voltage
test.
1. Disconnect the main AC input power to
the machine.
3. Locate the following leads on plug J1
(see Figure F.9):
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F-30
TROUBLESHOOTING AND REPAIR
POWER MIG 255C
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NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM
0 VOLTS
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20.0 V
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F-31
TROUBLESHOOTING AND REPAIR
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F-31
2.5 ms
SCOPE SETTINGS
This is a typical DC output voltage waveform
generated from a properly operating Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
machine. Note that each vertical division
represents 20 volts and that each horizontal Horizontal Sweep . . . . . . . . . 2.5 ms/Div
division represents 2.5 milliseconds in time.
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
NOTE:
Scope probes connected at
machine output terminals: (+) probe to elec- Trigger . . . . . . . . . . . . . . . . . . . . Internal
trode, (-) probe to work.
POWER MIG 255C
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F-32
TROUBLESHOOTING AND REPAIR
TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED
0 VOLTS
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F-32
20.0 V
5 ms
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MACHINE LOADED TO 250 AMPS AT 26 VDC
SCOPE SETTINGS
This is a typical DC output voltage waveform
generated from a properly operating Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
machine. Note that each vertical division
represents 20 volts and that each horizontal Horizontal Sweep . . . . . . . . . . 5 ms/Div
division represents 5 milliseconds in time.
The machine was loaded with a resistance Coupling . . . . . . . . . . . . . . . . . . . . . . DC
grid bank.
Trigger . . . . . . . . . . . . . . . . . . . . Internal
NOTE: Scope probes connected at machine
output terminals: (+) probe to electrode, (-)
probe to work.
POWER MIG 255C
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F-33
F-33
TROUBLESHOOTING AND REPAIR
ABNORMAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED
ONE OUTPUT SCR NOT FUNCTIONING
0 VOLTS
20.0 V
5 ms
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MACHINE LOADED TO 220 AMPS AT 22 VDC
SCOPE SETTINGS
This is NOT a typical DC output voltage
waveform. One output SCR is not functioning. 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 milliseconds in time. The machine was loaded
with a resistance grid bank.
Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
Horizontal Sweep . . . . . . . . . . 5 ms/Div
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
Trigger . . . . . . . . . . . . . . . . . . . . Internal
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NOTE: Scope probes connected at machine
output terminals: (+) probe to electrode, (-)
probe to work.
POWER MIG 255C
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ABNORMAL OPEN CIRCUIT VOLTAGE
OUTPUT CAPACITOR BANK NOT FUNCTIONING
0 VOLTS
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20.0 V
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F-34
TROUBLESHOOTING AND REPAIR
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F-34
5 ms
SCOPE SETTINGS
This is NOT the typical DC output voltage
waveform. The output capacitors are not Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
functioning. Note the lack of “filtering” in the
output waveform. The output capacitor bank Horizontal Sweep . . . . . . . . . . 5 ms/Div
was disconnected. Each vertical division
represents 20 volts and each horizontal divi- Coupling . . . . . . . . . . . . . . . . . . . . . . DC
sion represents 5 milliseconds in time.
Trigger . . . . . . . . . . . . . . . . . . . . Internal
NOTE: Scope probes connected at machine
output terminals: (+) probe to electrode, (-)
probe to work.
POWER MIG 255C
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TYPICAL SCR GATE VOLTAGE WAVEFORM
0 VOLTS
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2.00 V
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F-35
TROUBLESHOOTING AND REPAIR
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F-35
5 ms
SCOPE SETTINGS
This is a typical SCR gate pulse voltage
waveform. The machine was in an open Volts/Div . . . . . . . . . . . . . . . . . . 2.0 V/Div
circuit condition (no load) and operating
properly. Note that each vertical division Horizontal Sweep . . . . . . . . . . 5 ms/Div
represents 2 volts and each horizontal
division represents 5 milliseconds in time.
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
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NOTE: Scope probes connected at Plug J6 Trigger . . . . . . . . . . . . . . . . . . . . Internal
on the control board. The (+) probe to lead
G2, and the (-) probe to lead 204.
POWER MIG 255C
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F-36
NOTES
POWER MIG 255C
F-36
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F-37
TROUBLESHOOTING AND REPAIR
COMPONENT REPLACEMENT PROCEDURES
CONTROL PC BOARD REMOVAL AND REPLACEMENT
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
Return to Master TOC
Return to Section TOC
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
CAUTION
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.
------------------------------------------------------------------------------------------------------------------
DESCRIPTION
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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
POWER MIG 255C
F-37
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F-38
TROUBLESHOOTING AND REPAIR
F-38
CONTROL PC BOARD REMOVAL AND REPLACEMENT (continued)
FIGURE F.10 — WIRING HARNESS
AND MOLEX PLUG LOCATIONS.
J6
REMOVAL AND REPLACEMENT
PROCEDURE
1. Disconnect main input power the
machine.
J5
2. Open the side panels and remove the
tool tray using a 5/16 in. nutdriver.
J3
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J8
J1
J4
J2
POWER MIG 255C
3. Disconnect all wiring harness plugs and
Molex plugs connected to the control
board. See Figure F.10.
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F-39
TROUBLESHOOTING AND REPAIR
CONTROL PC BOARD REMOVAL AND REPLACEMENT (continued)
FIGURE F.11 — CONTROL BOARD MOUNTING.
TOOL
TRAY
PC CONTROL
BOARD
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MOUNTING
STANDOFF
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F-39
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NOTE: TOP COVER SHOWN
REMOVED FOR CLARITY.
4. Ensure a static electricity grounding
strap is used before handling the control PC boards.
7. When re-installing the control PC board
carefully secure board to mounting
standoffs.
5. Carefully remove the control PC board
from the mounting standoffs.
8. Install all plug connectors previously
removed from the control PC board.
6. Lift the control PC board straight up and
out from the machine.
9. Install the tool tray and close the side
panels.
POWER MIG 255C
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F-40
NOTES
POWER MIG 255C
F-40
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F-41
TROUBLESHOOTING AND REPAIR
WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
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Return to Section TOC
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DESCRIPTION
The 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 255C
F-41
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F-42
WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT (continued)
FIGURE F.12 — WIRE DRIVE ASSEMBLY REMOVAL
15
4D
2
16
3F
3
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4A
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F-42
TROUBLESHOOTING AND REPAIR
4B
20A
6A 6B
4C
5A
5B
20B
3K
18
3C
3A
3D
3B
14
7
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10
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9C
12
8
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5D
9B
3H
3J
5C
17A
2
3
3A
3B
3C
3D
3E
3F
3G
3H
3J
3K
4A
4B
4C
4D
4E
4F
4G
5A
5B
5C
5D
6A
17D
17C
Wire Drive Final Assembly, Includes:
Wire Drive Assembly, Includes:
Gearbox Mounting Panel
Feedplate Assembly, Includes:
Connection Bar
Socket Head Cap Screw
Plain Washer
Retaining Ring
Idle Arm (Not Shown)
Adjustment Arm Assembly
Roll Pin (Not Shown)
1/4-20 x .50 HHCS
Lock Washer
Plain Washer
Motor Gearbox Assembly, Includes:
Woodruff Key
Snap Ring
Tach Sensor
Ring Magnet (Not Shown)
Lock Washer (Not Shown)
Phillips Pan Head Screw (Not Shown)
Drive Gear
Collar
Lock Washer
Metric Screw
Ball Housing
POWER MIG 255C
11
9A
13
17B
6B
7
8
9A
9B
9C
10
11
12
13
14
15
16
17A
17B
17C
17D
18
19
20A
20B
21
Set Screw
Knurled Knob
Gun Adapter Assembly
Feedplate Cover
1/4-20 x .50 HHCS
Lock Washer
Drive Roll Shaft Assembly
Drive Hub Retainer
Inner Wire Guide (.035/.045)
Drive Roll (.035/.045)
Outer Guide Assembly
Wire Drive Compartment
#10-24 HLN - Nylon Insert
Lead
1/2-13x1.00 HHCS
Lock Washer
Plain Washer
Grommet
Decal (Not Shown)
Trigger Lead Assembly
Self Tapping Screw (Not Shown)
Decal (Not Shown)
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F-43
TROUBLESHOOTING AND REPAIR
WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT (continued)
11. Swing the idle arm up and away from
the wire drive assembly.
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.
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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.
6. Disconnect the wire connectors J13
and J12 to the motor/gearbox assembly. 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.
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8. Use pliers to remove the hose clamp
and flex hose from the wire drive
assembly.
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F-43
9. Remove the outer guide assembly from
the wire drive assembly by loosening
the thumb screws until the outer guide
can be removed.
10. Rotate the adjustment arm assembly
counterclockwise to release the tension
on the idle arm.
POWER MIG 255C
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 assembly.
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 securing the motor/gearbox assembly to the
wire drive assembly.
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.
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F-44
NOTES
POWER MIG 255C
F-44
TROUBLESHOOTING AND REPAIR
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F-45
SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENT
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
Return to Master TOC
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DESCRIPTION
The procedure will aid the technician in the removal and replacement of the SCR
assembly.
MATERIALS NEEDED
1/2
1/2
3/8
3/8
in.
in.
in.
in.
Open end wrench
Socket wrench, universal tool, and extension
Nutdriver
Open end wrench
POWER MIG 255C
F-45
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F-46
SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENT (continued)
PROCEDURE
1. Remove the case side panels using a
3/8 in. nutdriver.
2. Disconnect lead #208S and transformer lead X1 from the heat sink on
the left side of the machine using a 1/2
in. socket wrench. See Figure F.13.
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a. Thin lead is always on the outboard
side of the connection.
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F-46
TROUBLESHOOTING AND REPAIR
3. Disconnect lead #204 and heavy aluminum 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 negative 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.
FIGURE F.13 — LEFT HEAT SINK
LEAD DISCONNECTION.
LEFT
HEAT SINK
MIDDLE
HEAT SINK
LEAD X1
LEAD
#208S
POWER MIG 255C
HEAVY
LEAD LEAD
#204S
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F-47
TROUBLESHOOTING AND REPAIR
F-47
SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENT (continued)
FIGURE F.15 — RIGHT HEAT SINK LEAD DISCONNECTION.
SCR
ASSEMBLY
SCR DIODE
LEAD
LEAD
#320B
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LEAD
#320
LEAD
#209S
LEAD
X4
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.
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.
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10. Reassemble the SCR assembly in the
reverse order.
POWER MIG 255C
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F-48
NOTES
POWER MIG 255C
F-48
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F-49
TROUBLESHOOTING AND REPAIR
CAPACITOR BANK REMOVAL AND REPLACEMENT
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
Return to Master TOC
Return to Section TOC
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
WARNING
The liquid electrode in the capacitors is toxic. Do not touch the capacitors with
any part of your body.
-------------------------------------------------------------------------------------------------------------------
DESCRIPTION
The procedure will aid the technician in the removal and replacement of the capacitor
bank.
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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 255C
F-49
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F-50
TROUBLESHOOTING AND REPAIR
F-50
CAPACITOR BANK REMOVAL AND REPLACEMENT (continued)
FIGURE F.16 — LOCATION OF CAPACITOR BANK REMOVAL AND REPLACEMENT COMPONENTS.
LEAD
#206
SCR DIODE
LEAD
CAPACITOR
BANK
LEAD
#206B
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SHUNT
LEADS
X1 AND X2
POWER
ENHANCEMENT
CHOKE LEAD
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OUTPUT
CHOKE LEAD
tive capacitor bank buss bar using a
1/2 in. open end wrench.
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.
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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 wrenches.
5. Remove the shunt, leads 206, 206B,
and the SCR diode lead from the negaPOWER MIG 255C
6. Remove the choke lead and lead 204B
from the positive capacitor bank buss
bar using two 1/2 in. open end wrenches.
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.
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F-51
TROUBLESHOOTING AND REPAIR
MAIN TRANSFORMER AND OUTPUT CHOKE
REMOVAL AND REPLACEMENT
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
Return to Master TOC
Return to Master TOC
Return to Master TOC
Return to Section TOC
Return to Section TOC
Return to Section TOC
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
DESCRIPTION
The 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 255C
F-51
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F-52
TROUBLESHOOTING AND REPAIR
MAIN TRANSFORMER AND OUTPUT CHOKE
REMOVAL AND REPLACEMENT (continued)
FIGURE F.17 — MAIN TRANSFORMER REMOVAL.
LEAD
X1
OUTPUT
CHOKE
LEAD
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OUTPUT
CHOKE
POSITIVE
LEAD
NOTE: PLUG-IN LEADS ARE
NOT SHOWN FOR
CLARITY.
LEAD
X4
LEADS
X2 AND X3
MAIN
TRANSFORMER
POWER
ENHANCEMENT
CHOKE
PROCEDURE
1. Disconnect main input power to the
machine.
2. Remove the case side panels using a
3/8 in. nutdriver.
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3. Test that the capacitors are discharged
using a volt ohmmeter. Polarity must
be observed.
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F-52
4. Remove lead X1 from the left side SCR
heat sink assembly using a 1/2 in. socket 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. socket wrench, extender and universal
adapter.
POWER MIG 255C
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 wrenches.
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.
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F-53
TROUBLESHOOTING AND REPAIR
MAIN TRANSFORMER AND OUTPUT CHOKE
REMOVAL AND REPLACEMENT (continued)
11. Unplug and label leads X5, X6, X7, X8, and X9.
These leads have connectors near the transformer which can be disconnected.
14. Remove the four nuts and washers mounting the
transformer to the floor of the machine using a
1/2 in. wrench.
12. Disconnect the output choke lead from the positive capacitor bank buss using two 1/2 in. open
end wrenches.
15. Carefully remove the main transformer and choke
assembly.
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13. Remove the other output choke lead from the
positive output terminal using a 1/2 in. wrench.
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F-53
16. Reassemble the main transformer and choke
assembly in the reverse order.
13. Remove all cable ties, wire mounts, and any harness type that could get in the way during transformer removal using wire cutters and screw
driver.
POWER MIG 255C
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F-54
NOTES
POWER MIG 255C
F-54
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F-55
TROUBLESHOOTING AND REPAIR
FAN MOTOR ASSEMBLY REMOVAL AND REPLACEMENT
WARNING
Service and repair should only be performed by 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 precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric service department for
technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
-------------------------------------------------------------------------------------------------------------------
Return to Master TOC
Return to Master TOC
Return to Master TOC
Return to Section TOC
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Return to Section TOC
DESCRIPTION
The 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 255C
F-55
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F-56
FAN MOTOR ASSEMBLY REMOVAL AND REPLACEMENT (continued)
FIGURE F.18 — FAN MOTOR ASSEMBLY REMOVAL.
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FAN
BLADE
LEAD
#353
LEAD
#352
FAN
MOTOR
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.
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3. Remove the fan blade. Note the position of the fan on the shaft for reassembly.
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F-56
TROUBLESHOOTING AND REPAIR
a. Use a screwdriver to loosen the fan
blade clamp.
b. Slide the fan blade off the motor
shaft.
FAN
BLADE
CLAMP
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 components in reverse order of removal.
4. Remove the fan motor.
POWER MIG 255C
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F-57
RETEST AFTER REPAIR
INPUT IDLE AMPS AND WATTS
Input Volts/Hertz
Maximum Idle Amps
Maximum Idle Watts
230/60
7.0
400
OPEN CIRCUIT VOLTAGE
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35-40 VDC
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F-57
TROUBLESHOOTING AND REPAIR
WIRE SPEED RANGE
50 - 700 IPM (1.27 - 17.8 m/minute)
POWER MIG 255C
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NOTES
POWER MIG 255C
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Section G-1
TABLE OF CONTENTS
- ELECTRICAL DIAGRAMS SECTION -
Section G-1
Electrical Diagrams ...............................................................................................Section G
Wiring Diagram - Entire Machine - Code 11192 - (L12464) . . . . . . . . . . . . . . . . . . . .G-2
Wiring Diagram - Entire Machine - Code 11218 - (L12506) . . . . . . . . . . . . . . . . . . . .G-3
Schematic - Entire Machine - (G4752) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-4
Schematic - Control PC Board - (G4823-2D1 Sheet 1) . . . . . . . . . . . . . . . . . . . . . . .G-5
Schematic - Control PC Board - (G4823-2D1 Sheet 2) . . . . . . . . . . . . . . . . . . . . . . .G-6
PC Board Assembly - Control - (G4824-2D1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-8
Schematic - Display PC Board - (L10951) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-9
PC Board Assembly - Display - (L10952-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-10
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Schematic - Control PC Board - (G4823-2D1 Sheet 3) . . . . . . . . . . . . . . . . . . . . . . .G-7
POWER MIG 255C
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ELECTRICAL DIAGRAMS
G-2
WIRING DIAGRAM - ENTIRE MACHINE - CODE 11192 (L12464)
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G-2
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.
POWER MIG 255C
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ELECTRICAL DIAGRAMS
G-3
WIRING DIAGRAM - ENTIRE MACHINE CODE 11218 (L12506)
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G-3
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.
POWER MIG 255C
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ELECTRICAL DIAGRAMS
G-4
SCHEMATIC - ENTIRE MACHINE - (G4752)
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G-4
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
POWER MIG 255C
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ELECTRICAL DIAGRAMS
G-5
SCHEMATIC - CONTROL PC BOARD - (G4823-2D1 SHEET 1)
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G-5
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
POWER MIG 255C
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ELECTRICAL DIAGRAMS
G-6
SCHEMATIC - CONTROL PC BOARD - (G4823-2D1 SHEET 2)
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G-6
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
POWER MIG 255C
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ELECTRICAL DIAGRAMS
G-7
SCHEMATIC - CONTROL PC BOARD - (G4823-2D1 SHEET 3)
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G-7
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
POWER MIG 255C
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G-8
G-8
ELECTRICAL DIAGRAMS
PC BOARD ASSEMBLY - CONTROL - (G4824-2D1)
ITEM (USED WITH)*
1
2 (Q4)*
3 (Q4)*
4 (Q4)*
5 (X1)*
6 (Q4)*
7 (X1)*
8 (Q4)*
QTY
1
1
1
AS REQ
AS REQ
1
1
1
PART NUMBER
G4824-D
CF000003
E106A-13
E1868
E2861
S18104-1
S20209-52
T13746
DESCRIPTION
PC BOARD BLANK
6-32 X .375 ROUND HEAD MACHINE SCREW
# 6 LOCK WASHER
THERMO JOINT COMPOUND
RTV SEALANT
HEAT SINK,ALUMINUM,EXTRUDED,FOR 1 TO-220
SOCKET,IC,PLCC,52-PIN
6-32 HEX NUT
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REFER TO ELECTRONIC COMPONENT DATABASE FOR SPECIFICATIONS ON ITEMS LISTED BELOW
REFERENCES
C3, C4, C9, C65
C5, C6, C18, C19, C35,
C51, C54
C7, C66
C8, C14, C20, C29, C36,
C37, C38, C39, C43, C48,
C49, C52, C53, C55, C56,
C62, C63, C64
C10, C17, C22, C23, C24,
C25, C26, C30, C31, C32,
C33, C34, C40, C41, C46,
C57, C58, C60, C61, C71,
C72, C73
a
C15
C16
C27
C28
C47
C67, C68
C69, C70
D8, D9, D10, D11, D12,
D13, D14, D16, D19, D20,
D21, D22, D24, D25, D29,
D33, D34, D35, D36, D38,
D39, D41, D46, D47, D48,
D49, D50, D55, D56, D57,
D58, D59
D23, D37
DZ2, DZ3, DZ4, DZ5, DZ6
DZ7, DZ8
DZ9, DZ10, DZ11, DZ12,
DZ13, DZ14
J1
J2
J3
J4
J5
J6
J8
L3, L4
OCI1, OCI2
OCI3
Q1, Q2, Q3, Q6, Q11, Q12,
Q13, Q14
Q4
Q5, Q9, Q15, Q16
Q7, Q10, Q18, Q19
Q8, Q17
Q20, Q21
NOTE:
QTY
4
PART NUMBER DESCRIPTION
S13490-42
CAPACITOR,TAEL,1.0,35V,10%
CAPACITOR,CD,.0047/.005,1400V,20%
2
S13490-181
CAPACITOR,ALEL,22,63V,20%
CAPACITOR,CEMO,.022,50V,20%
CAPACITOR,CEMO,0.1, 50V,10%
2
1
1
1
1
1
2
2
S16668-1
S16668-8
S13490-179
S13490-182
S13490-197
S16668-6
S20500-2
T11577-46K
CAPACITOR,CEMO,22pF, 100V,5%
CAPACITOR,CEMO,330pF,100V,5%
CAPACITOR,ALEL,1000,35V,20%
CAPACITOR,ALEL,3300,63V,20%
CAPACITOR,ALEL,82,35V,20%,LOW-ESR
CAPACITOR,CEMO,4700pF,50V,10%
CAPACITOR,PPMF,0.47,630V,10%,BOX
CAPACITOR,CD,.05,600V,+80/-20%
DIODE,AXLDS,1A,400V
2
5
2
T12705-23
T12702-45
T12702-52
1
1
1
1
1
1
1
2
2
1
S18248-8
S18248-14
S18248-12
S24020-10
S18248-16
S18248-6
S18248-4
T12218-7
S15000-30
S15000-31
1
4
4
2
2
T12704-41
T12704-35
T12704-88
T12704-69
T12704-109
DIODE,SCHOTTKY,AXLDS,1A,30V,1N5818
ZENER DIODE,1W,18V,5%,1N4746A
ZENER DIODE,1W,5.1V,5%,1N4733A
ZENER DIODE,1W,6.2V,5%,1N4735A
CONNECTOR,MOLEX,MINI,PCB,8-PIN
CONNECTOR,MOLEX,MINI,PCB,14-PIN
CONNECTOR,MOLEX,MINI,PCB,12-PIN
CONNECTOR,MOLEX,MINI,PCB,10-PIN,TIN
CONNECTOR,MOLEX,MINI,PCB,16-PIN
CONNECTOR,MOLEX,MINI,PCB,6-PIN
CONNECTOR,MOLEX,MINI,PCB,4-PIN
CHOKE,330UH,10%,110MA, MOLDED
OPTOCOUPLER,TRIAC,DRV,RANDOM,800V
OPTOCOUPLER,TRIAC,DRV,RANDOM,800V
TRANSISTOR,NPN,TO226,0.5A,40V,2N4401
TRANSISTOR,N,TO220,8A,150V,MJE15030
TRANSISTOR,NPN,TO226,0.5A, 300V,MPS-A42
TRANSISTOR,NMF,TO220,45A,100V(SS)
TRANSISTOR,PNP,TO226,0.5A, 40V,2N4403
TRANSISTOR,NMF,IPAK,TO-251,10A,100V(SS)
R2, R30, R42, R45, R70,
R90, R103, R148, R182,
R188
R13, R22, R93, R94, R132
R14, R15, R27, R123
R18, R20, R24, R80
R19, R21, R58, R83, R144,
R178, R179, R180
R25, R26, R49, R50
R28, R61, R142, R143,
R147, R191
R29, R100, R110
R31, R106, R150, R193
R32
R33, R38, R79, R149
R34, R40
R35, R51, R181
R36
R37, R59, R66, R69, R73,
R74, R86, R87
R39, R68, R71, R72, R91,
R92, R111
RESISTOR,MF,1/4W,4.75K,1%
5
4
4
S19400-6810
S19400-15R0
S19400-5620
RESISTOR,MF,1/4W,681,1%
RESISTOR,MF,1/4W,15.0,1%
RESISTOR,MF,1/4W,562,1%
4
S25365-51R0
RESISTOR,STAND-UP,WW,5W,51.0,5%
3
4
1
4
2
3
1
S19400-1501
S19400-5621
S19400-2672
S19400-2212
S19400-33R2
S19400-1502
S19400-2671
RESISTOR,MF,1/4W,1.50K,1%
RESISTOR,MF,1/4W,5.62K,1%
RESISTOR,MF,1/4W,26.7K,1%
RESISTOR,MF,1/4W,22.1K,1%
RESISTOR,MF,1/4W,33.2,1%
RESISTOR,MF,1/4W,15.0K,1%
RESISTOR,MF,1/4W,2.67K,1%
RESISTOR,MF,1/4W,2.21K,1%
RESISTOR,MF,1/4W,6.81K,1%
RESISTOR,MF,1/4W,44.2K,1%
RESISTOR,MF,1/4W,3.32K,1%
R41, R65, R75, R84, R112,
R113, R133, R134, R137,
R138, R139, R140, R141
R43, R183
R44, R47, R109, R145,
R146
R48
R52, R98
R53
R54
R55, R56
R57
R60
R62, R63, R76, R77, R78,
R82, R95, R105, R124,
R125, R126, R127, R128,
R129, R130, R131
R64, R67
R88, R89
R99
R101, R102
R104, R152
R107, R151
R108
R116
R135, R136, R187
R153, R154, R155
R156, R157
R158, R159
R160, R161, R162, R163,
R184, R185, R186, R190
R164
R167, R168
R169, R170, R171, R172,
R173, R174, R175
R176, R177
R192
TP1, TP2
TP3, TP4
TP7, TP8, TP9
TRI1
X1
X2
X3
X4, X5
X6
X8, X14
X9, X13
X10, X11
X12
X15
Y1
RESISTOR,MF,1/4W,10.0K,1%
2
S19400-1004
RESISTOR,MF,1/4W,1.00M,1%
1
2
1
1
2
1
1
S19400-2801
S19400-3011
S19400-5111
S25365-00R1
S19400-26R7
S19400-2430
S19400-2432
RESISTOR,MF,1/4W,2.80K,1%
RESISTOR,MF,1/4W,3.01K,1%
RESISTOR,MF,1/4W,5.11K,1%
RESISTOR,STAND-UP,WW,5W,0.1,5%
RESISTOR,MF,1/4W,26.7,1%
RESISTOR,MF,1/4W,243,1%
RESISTOR,MF,1/4W,24.3K,1%
RESISTOR,MF,1/4W,1.00K,1%
RESISTOR,MF,1/4W,100,1%
2
2
1
2
2
2
1
1
3
3
2
2
S19400-5110
S19400-1622
S19400-1652
S19400-1372
S19400-7500
S19400-4750
S19400-2670
S19400-2802
S19400-4752
S18380-14
S19400-3320
S19400-2210
RESISTOR,MF,1/4W,511,1%
RESISTOR,MF,1/4W,16.2K,1%
RESISTOR,MF,1/4W,16.5K,1%
RESISTOR,MF,1/4W,13.7K,1%
RESISTOR,MF,1/4W,750,1%
RESISTOR,MF,1/4W,475,1%
RESISTOR,MF,1/4W,267,1%
RESISTOR,MF,1/4W,28.0K,1%
RESISTOR,MF,1/4W,47.5K ,1%
THERMISTOR,PTC,500OHMS,28mA
RESISTOR,MF,1/4W,332,1%
RESISTOR,MF,1/4W,221,1%
1
2
S18380-5
S25365-10R0
THERMISTOR,PTC,0.5-1.17 OHMS,0.5A
RESISTOR,STAND-UP,WW,5W,10.0,5%
2
1
2
2
3
1
1
1
1
2
1
2
2
2
1
1
1
S19400-2000
S19400-3322
T13640-15K
T13640-9K
T13640-18
S15161-27
M15101-10
M15102-3
S17900-8
S15128-11
S15128-16
S15018-4
S15018-6
S15128-10
S15128-5
S15128-4
S16665-11
RESISTOR,MF,1/4W,200,1%
RESISTOR,MF,1/4W,33.2K,1%
MOV,50VRMS,15J,14MM
MOV,75VRMS,22J,14MM
MOV,320VRMS,150J,20MM
TRIAC,TO220,8A,800V
IC,CMOS,MCU,ONE-TIME-PROM,PLCC,68HC711E9C
IC,CMOS,UNDERVOLT-SENSING,RESET,MCU(SS)
IC,CMOS,INVERTER,SCHMITT,HEX,HC14A(SS)
IC,COMPARATOR,QUAD,2901N
IC,OP-AMP,QUAD,HIGH-PERF,1014
IC,CMOS,INVERTER,SCHMITT, HEX,4584(SS)
IC,CMOS,SWITCH,ANALOG,QUAD, 4066(SS)
VOLTAGE REF,ADJ, PRECISION,431I
IC,VOLT REG,FIXED,3-T,(+),1A,5V,TO220
OP-AMP,QUAD, GEN-PURPOSE,224N
CRYSTAL,QUARTZ,8.000MHZ,ATS-49
RESISTOR,MF,1/4W,2.00K,1%
RESISTOR,MF,1/4W,100K,1%
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.
POWER MIG 255C
L 10951
Return to Master TOC
Return to Section TOC
515
500
R12
J10
7
J10
SCK
MOSI
X5
475
12
475
R3
R14
221
IN
C1
4.7
35V
1
R9
X5
11
R8
X5
9
7805
GND
X5
R13
221
R4
X1
Vdd
X3
OUT
MC14489
18
15V
Vss
14
CLOCK
10
/ENABLE
18
DATA OUT
500
8
.0047
C7
50V
500
3
C10
50V
13
BANK2
9
Vdd
X4
0.1
MC14489
Vss
14
g
20
f
1
Rx
8
C8
.0047
16
BANK4
a
7
15
BANK3
b
6
3
Vdd
c
5
X4
R2
3
C3
50V
DR.
11
Vss
14
9
d
4
BANK1
e
2
17
BANK5
h
19
12
DATA IN
10
/ENABLE
g
20
11
CLOCK
f
1
18
DATA OUT
Vss
Rx
14
X5
0.1
HEXINV
C4
8
0.1
5
3
X5
X5
DISP3
10
1
2
3
4
5
6
7
9
10
DISP7
7
4
9
DISP2
5
6
10
7
9
8
3
7
9
10
DISP6
DISP1
MC14489
1
1
2
8
2
3
4
4
5
5
6
6
7
9
MC14489
8
475
C9
2
.0047
500
50V
10
50V
500
8
VOLTS
DISP5
LED3
10
2/20/98
NONE
CLEVELAND, OHIO U.S.A.
THE LINCOLN ELECTRIC CO.
FILENAME: L10951-1AB
CHK.
(UNLESS OTHERWISE SPECIFIED)
SUBJECT
TYPE
EQUIP.
UNLESS OTHERWISE SPECIFIED)
10
DATE
5
UNLESS OTHERWISE SPECIFIED)
4
SCALE
6
GT
7
8
3-12-99
DATA IN
6
3
XA
12
5
2
Ch’ge.Sht.No.
19
8
NUMBER.
2
h
3
NOT SHOW THE EXACT COMPONENTS OR CIRCUITRY OF CONTROLS HAVING A COMMON CODE
e
BANK5
1
2
WITHOUT AFFECTING THE INTERCHANGEABILITY OF A COMPLETE BOARD, THIS DIAGRAM MAY
BANK1
17
1
1A, 400V
9
4
DIODES =
4
8
1/4W
d
3
RESISTORS = Ohms (
BANK2
2
MFD ( .022/50V
13
1
CAPACITORS =
5
X3
ELECTRICAL SYMBOLS PER E1537
6
c
BANK4
SINCE COMPONENTS OR CIRCUITRY ON A PRINTED CIRCUIT BOARD MAY CHANGE
13
b
Vdd
GENERAL INFORMATION
500
N.A.
R10
7
BANK3
3
NOTES :
LATCH
a
15
1.50K
R11
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Return to Section TOC
16
1.50K
6
10K
J10
10K
5
R7
4
R6
J10
10K
R5
Return to Master TOC
Return to Section TOC
10
DISP- 7
LED- 3
X- 5
SUP’S’D’G.
SHT.
NO.
L 10951
SCHEMATIC, DISPLAY PCB
POWERMIG 255
EARTH GROUND CONNECTION
FRAME CONNECTION
COMMON CONNECTION
POWER SUPPLY SOURCE POINT
VOLTAGE NET
1
14
CD-
R-
SUPPLY
LABELS
LAST NO. USED
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G-9
ELECTRICAL DIAGRAMS
G-9
SCHEMATIC - DISPLAY PC BOARD (L10951)
500
500
R1
221
221
500
D1
+5VA
221
221
14
50V
6
C2
J10
7
4
500
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
POWER MIG 255C
18/15
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
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)
DISP3
DISP2
X4
DISPLAY
L10952-1
1.44
DISP1
X5
X3
REF.
SUP’S’D’G
NO.
SHT.
L
STANDARD DISPLAY P.C. BD. ASSEMBLY
CHK
TYPE
B
C3
C2
C4
A
X1
D1
C10
DISP5
C9
J10
LED3
R11
C7
R8
R7
R5
R10
R1
R2
R3
R4
R13
R14
.49
DISP6
R12
C8
R9
R6
DISP7
C1
Return to Master TOC
1.64
XA
Ch’ge. Sht. No.
DISP6,DISP7
~.04
Return to Section TOC
DATE 5-20-98
S13490-39
C3,C4,C10
DR R.T.
4.7/35
SUBJECT
POWER MIG 255
1
S13490-25
FULL
C2
IDENTIFICATION
PART NO.
SCALE
EQUIP.
1
CLEVELAND, OHIO U.S.A.
REQ’D
THE LINCOLN ELECTRIC CO.
ITEM
C1
10952-1
PC BOARD ASSEMBLY - DISPLAY - (L10952)
4-28-2000D
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G-10
ELECTRICAL DIAGRAMS
3-12-99
Return to Section TOC
Return to Section TOC
G-10
0
~.04
5.80
Return to Master TOC
.20
2.90
5.60
L 10952-1
Return to Section TOC
0
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.
POWER MIG 255C
Return to Master TOC
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 column troubleshooting chart, please share this information with us. Please include the
machine’s code number and how the problem was resolved.
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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__________________
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Your Company__________________________
Your Name_____________________________
Please give detailed description below:
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
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___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
SD287 04/06