Lincoln Electric SVM170-A User Manual

POWER MIG 255C

SVM170-A

October, 2006

Safety Depends on You

Lincoln arc welding and cutting
equipment is designed and built
with safety in mind. However,
your overall safety can be
increased by proper installation
. . . and thoughtful operation on
your part. DO NOT INSTALL,

OPERATE OR REPAIR THIS
EQUIPMENT WITHOUT READ­ING THIS MANUAL AND THE
SAFETY PRECAUTIONS CON­TAINED THROUGHOUT. And,

most importantly, think before
you act and be careful.

SERVICE MANUAL

For use with machines having Code Number : 11192, 11218

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• Sales and Service through Subsidiaries and Distributors Worldwide •

Cleveland, Ohio 44117-1199 U.S.A. TEL: [phone] FAX: [phone] WEB SITE: www.lincolnelectric.com

• World's Leader in Welding and Cutting Products •

Copyright © 2006 Lincoln Global Inc.

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FOR ENGINE
powered equipment.

1.a. Turn the engine off before troubleshooting and maintenance
work unless the maintenance work requires it to be running.

____________________________________________________

1.b.Operate engines in open, well-ventilated
areas or vent the engine exhaust fumes
outdoors.

____________________________________________________

1.c. Do not add the fuel near an open flame 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.

___________________________________________________

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.

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SAFETY

i

ARC WELDING CAN BE HAZARDOUS. PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH.
KEEP CHILDREN AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.

Read and understand the following safety highlights. For additional safety information, it is strongly recommended that you
purchase a copy of “Safety in Welding & Cutting - ANSI Standard Z49.1” from the American Welding Society , P.O. Box 351040,
Miami, Florida 33135 or CSA Standard W117.2-1974. AFree copy of “Arc Welding Safety” booklet E205 is available from the
Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199.

BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE AND REPAIR PROCEDURES ARE
PERFORMED ONLY BY QUALIFIED INDIVIDUALS.

WARNING

Mar ‘95

ELECTRIC AND
MAGNETIC FIELDS
may be dangerous

2.a. Electric current flowing through any conductor causes
localized Electric and Magnetic Fields (EMF). Welding
current creates EMF fields around welding cables and
welding machines

2.b. EMF fields may interfere with some pacemakers, and
welders having a pacemaker should consult their physician
before welding.

2.c. Exposure to EMF fields in welding may have other health
effects which are now not known.

2.d. All welders should use the following procedures in order to
minimize exposure to EMF fields from the welding circuit:

2.d.1.

Route the electrode and work cables together - Secure
them with tape when possible.

2.d.2. Never coil the electrode lead around your body.

2.d.3. Do not place your body between the electrode and

work cables. If the electrode cable is on your right
side, the work cable should also be on your right side.

2.d.4. Connect the work cable to the workpiece as close as

possible to the area being welded.

2.d.5. Do not work next to welding power source.

1.h. To avoid scalding, do not remove the
radiator pressure cap when the engine is
hot.

CALIFORNIA PROPOSITION 65 WARNINGS

Diesel engine exhaust and some of its constituents
are known to the State of California to cause can­cer, birth defects, and other reproductive harm.

The engine exhaust from this product contains
chemicals known to the State of California to cause
cancer, birth defects, or other reproductive harm.

The Above For Diesel Engines

The Above For Gasoline Engines

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ARC RAYS can burn.

4.a. Use a shield with the proper filter and cover
plates to protect your eyes from sparks and
the rays of the arc when welding or observing
open arc welding. Headshield and filter lens
should conform to ANSI Z87. I standards.

4.b. Use suitable clothing made from durable flame-resistant
material to protect your skin and that of your helpers from
the arc rays.

4.c. Protect other nearby personnel with suitable, non-flammable
screening and/or warn them not to watch the arc nor expose
themselves to the arc rays or to hot spatter or metal.

ELECTRIC SHOCK can kill.

3.a. The electrode and work (or ground) circuits
are electrically “hot” when the welder is on.
Do not touch these “hot” parts with your bare
skin or wet clothing. Wear dry, hole-free
gloves to insulate hands.

3.b. Insulate yourself from work and ground using dry insulation.
Make certain the insulation is large enough to cover your full
area of physical contact with work and ground.

In addition to the normal safety precautions, if welding
must be performed under electrically hazardous
conditions (in damp locations or while wearing wet
clothing; on metal structures such as floors, gratings or
scaffolds; when in cramped positions such as sitting,
kneeling or lying, if there is a high risk of unavoidable or
accidental contact with the workpiece or ground) use
the following equipment:

• Semiautomatic DC Constant Voltage (Wire) Welder.

• DC Manual (Stick) Welder.

• AC Welder with Reduced Voltage Control.

3.c. In semiautomatic or automatic wire welding, the electrode,
electrode reel, welding head, nozzle or semiautomatic
welding gun are also electrically “hot”.

3.d. Always be sure the work cable makes a good electrical
connection with the metal being welded. The connection
should be as close as possible to the area being welded.

3.e. Ground the work or metal to be welded to a good electrical
(earth) ground.

3.f.

Maintain the electrode holder, work clamp, welding cable and
welding machine in good, safe operating condition. Replace
damaged insulation.

3.g. Never dip the electrode in water for cooling.

3.h. Never simultaneously touch electrically “hot” parts of
electrode holders connected to two welders because voltage
between the two can be the total of the open circuit voltage
of both welders.

3.i. When working above floor level, use a safety belt to protect
yourself from a fall should you get a shock.

3.j. Also see Items 6.c. and 8.

FUMES AND GASES
can be dangerous.

5.a.Welding may produce fumes and gases
hazardous to health. Avoid breathing these
fumes and gases.When welding, keep
your head out of the fume. Use enough
ventilation and/or exhaust at the arc to keep

fumes and gases away from the breathing zone. When

welding with electrodes which require special
ventilation such as stainless or hard facing (see
instructions on container or MSDS) or on lead or
cadmium plated steel and other metals or coatings
which produce highly toxic fumes, keep exposure as
low as possible and below Threshold Limit Values (TLV)
using local exhaust or mechanical ventilation. In
confined spaces or in some circumstances, outdoors, a
respirator may be required. Additional precautions are
also required when welding on galvanized steel.

5. b. 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 OSHAPEL
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.

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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SAFETY

ii

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FOR ELECTRICALLY
powered equipment.

8.a. Turn off input power using the disconnect
switch at the fuse box before working on
the equipment.

8.b. Install equipment in accordance with the U.S. National
Electrical Code, all local codes and the manufacturer’s
recommendations.

8.c. Ground the equipment in accordance with the U.S. National
Electrical Code and the manufacturer’s recommendations.

CYLINDER may explode
if damaged.

7.a. Use only compressed gas cylinders
containing the correct shielding gas for the
process used and properly operating
regulators designed for the gas and

pressure used. All hoses, fittings, etc. should be suitable for
the application and maintained in good condition.

7.b. Always keep cylinders in an upright position securely
chained to an undercarriage or fixed support.

7.c. Cylinders should be located:

•Away from areas where they may be struck or subjected to

physical damage.

•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, VA22202.

Mar ‘95

WELDING SPARKS can
cause fire or explosion.

6.a.

Remove fire hazards from the welding area.

If this is not possible, cover them to prevent

the welding sparks from starting a fire.

Remember that welding sparks and hot
materials from welding can easily go through small cracks
and openings to adjacent areas. Avoid welding near
hydraulic lines. Have a fire extinguisher readily available.

6.b. Where compressed gases are to be used at the job site,
special precautions should be used to prevent hazardous
situations. Refer to “Safety in Welding and Cutting” (ANSI
Standard Z49.1) and the operating information for the
equipment being used.

6.c. When not welding, make certain no part of the electrode
circuit is touching the work or ground. Accidental contact can
cause overheating and create a fire hazard.

6.d. Do not heat, cut or weld tanks, drums or containers until the
proper steps have been taken to insure that such procedures
will not cause flammable or toxic vapors from substances
inside. They can cause an explosion even

though

they have
been “cleaned”. For information, purchase “Recommended
Safe Practices for the

Preparation

for Welding and Cutting of
Containers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding Society

(see address above).

6.e. Vent hollow castings or containers before heating, cutting or
welding. They may explode.

6.f.

Sparks and spatter are thrown from the welding arc. Wear oil
free protective garments such as leather gloves, heavy shirt,
cuffless trousers, high shoes and a cap over your hair. Wear
ear plugs when welding out of position or in confined places.
Always wear safety glasses with side shields when in a
welding area.

6.g. Connect the work cable to the work as close to the welding
area as practical. Work cables connected to the building
framework or other locations away from the welding area
increase the possibility of the welding current passing
through lifting chains, crane cables or other alternate circuits.
This can create fire hazards or overheat lifting chains or
cables until they fail.

6.h. Also see item 1.c.

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SAFETY

iii

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PRÉCAUTIONS DE SÛRETÉ

Pour votre propre protection lire et observer toutes les instructions
et les précautions de sûreté specifiques qui parraissent dans ce
manuel aussi bien que les précautions de sûreté générales 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:

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.

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.

5. Toujours porter des lunettes de sécurité dans la zone de
soudage. Utiliser des lunettes avec écrans lateraux dans les

zones où l’on pique le laitier.

6. Eloigner les matériaux inflammables ou les recouvrir afin de
prévenir tout risque d’incendie dû aux étincelles.

7. Quand on ne soude pas, poser la pince à une endroit isolé de
la masse. Un court-circuit accidental peut provoquer un
échauffement et un risque d’incendie.

8. S’assurer que la masse est connectée le plus prés possible de
la zone de travail qu’il est pratique de le faire. Si on place la
masse sur la charpente de la construction ou d’autres endroits
éloignés de la zone de travail, on augmente le risque de voir
passer le courant de soudage par les chaines de levage,
câbles de grue, ou autres circuits. Cela peut provoquer des
risques d’incendie ou d’echauffement des chaines et des
câbles jusqu’à ce qu’ils se rompent.

9. Assurer une ventilation suffisante dans la zone de soudage.
Ceci est particuliérement important pour le soudage de tôles
galvanisées plombées, ou cadmiées ou tout autre métal qui
produit des fumeés toxiques.

10. Ne pas souder en présence de vapeurs de chlore provenant
d’opérations de dégraissage, nettoyage ou pistolage. La
chaleur ou les rayons de l’arc peuvent réagir avec les vapeurs
du solvant pour produire du phosgéne (gas fortement toxique)
ou autres produits irritants.

11. Pour obtenir de plus amples renseignements sur la sûreté, voir
le code “Code for safety in welding and cutting” CSA Standard
W 117.2-1974.

PRÉCAUTIONS DE SÛRETÉ POUR
LES MACHINES À SOUDER À
TRANSFORMATEUR ET À
REDRESSEUR

1. Relier à la terre le chassis du poste conformement au code de
l’électricité et aux recommendations du fabricant. Le dispositif
de montage ou la piece à souder doit être branché à une
bonne mise à la terre.

2. Autant que possible, I’installation et l’entretien du poste seront
effectués par un électricien qualifié.

3. Avant de faires des travaux à l’interieur de poste, la debranch­er à l’interrupteur à la boite de fusibles.

4. Garder tous les couvercles et dispositifs de sûreté à leur place.

Mar. ‘93

iv

SAFETY

iv

vv

POWER MIG 255C

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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P-514

RETURN TO MAIN MENU

SECTION A

INSTALLATION

POWER MIG 255C

SECTION A

TABLE OF CONTENTS

-INSTALLATION SECTION-

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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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A-2

POWER MIG 255C

A-2

INSTALLATION

75°C Copper Wire 75°C Copper Wire

in Conduit in Conduit

Input Ampere AWG (IEC) Sizes AWG (IEC) Sizes

Input Voltage/ Fuse or Breaker Rating On (For lengths (For lengths

Frequency (Hz) Size (Super Lag) Nameplate up to 100 ft) exceeding 100 ft)

208/60 60 56 8 (10 mm2)6 (16 mm2)
230/60 60 52 10 (6 mm2)8 (10 mm2)
460/60 30 24 14 (2.5 mm2) 12 (4 mm2)
575/60 25 19 14 (2.5 mm2) 12 (4 mm2)

NOTE: Use #10 AWG Grounding Wire

TECHNICAL SPECIFICATIONS – POWER MIG 255C

INPUT – SINGLE PHASE ONLY

RATED OUTPUT

OUTPUT

RECOMMENDED INPUT WIRE AND FUSE SIZES

Height Width Depth Weight

31.79 in. 18.88 in. 38.78 in. 220 Ibs
808 mm 480 mm 985 mm 100 kg

PHYSICAL DIMENSIONS

Wire Speed 50 – 700 IPM (1.27 – 17.8 m/minute)

WIRE SPEED RANGE

Standard Voltage/Frequency

Input Current @ 200 Amp Rated Output Input Current @ 250 Amp Rated Output

208/230/60 Hz *47/44 Amps 56/52

230/460/575/60 Hz 41/20/16 Amps 50/24/19

Duty Cycle

Amps

Volts at Rated Amperes

40% 250 Amps 26 Volts
60% 200 Amps 28 Volts

100% 145 Amps 26 Volts

Welding Current Range Maximum Open Circuit Voltage Welding Voltage Range

(Continuous)

30 – 300 Amps 40 Volts 10-28 Volts

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INPUT POWER, GROUNDING AND
CONNECTION DIAGRAMS

------------------------------------------------------------------------

1. Before starting the installation, check with the
local power company if there is any question
about whether your power supply is adequate for
the voltage, amperes, phase, and frequency 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.

Make certain that the input power is electrically
disconnected before removing the screw on the
reconnect panel access cover.

------------------------------------------------------------------------

A-3

INSTALLATION

POWER MIG 255C

A-3

Read entire installation section before starting
installation.

SAFETY PRECAUTIONS

ELECTRIC SHOCK can kill.

• Only qualified personnel should perform this
installation.

• Only personnel that have read and under­stood the POWER MIG 255C Operating
Manual should install and operate this equip­ment.

• Machine must be grounded per any national,
local or other applicable electrical codes.

• The POWER MIG power switch is to be in the
OFF position when installing work cable and
gun and when connecting other equipment.

WARNING

------------------------------------------------------------------------

UNCRATING THE POWER MIG 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.

LOCATION

Locate the welder in a dry location where there is free
circulation of clean air into the louvers in the back and
out the front. A location that minimizes the amount of
smoke and dirt drawn into the rear louvers reduces the
chance of dirt accumulation that can block air pas­sages and cause overheating.

ELECTRIC SHOCK can kill.

• Do not touch electrically live parts such as
output terminals or internal wiring.

• All input power must be electrically discon­nected before proceeding.

WARNING

WARNING

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4. Using the instructions in Figure A.3, have a qual-
ified electrician connect the receptacle or cable to
the input power lines and the system ground per
the U.S. National Electrical Code and any 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.

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.

A-4

INSTALLATION

POWER MIG 255C

A-4

FIGURE A.1 — DUAL VOLTAGE MACHINE INPUT CONNECTIONS.

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A-5

INSTALLATION

POWER MIG 255C

A-5

FIGURE A.3 — RECEPTACLE DIAGRAM.

CONNECT TO A SYSTEM
GROUNDING WIRE. SEE
THE UNITED STATES
NATIONALELECTRICAL
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 ATWO 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.

FIGURE A.2 — TRIPLE VOLTAGE MACHINE INPUT CONNECTIONS.

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A-6

INSTALLATION

POWER MIG 255C

A-6

GUN AND CABLE INSTALLATION

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.

------------------------------------------------------------------------

1. Lay the cable out straight.

2. Unscrew knurled screw on the drive unit front end

(inside wire feed compartment) until tip of screw
no longer protrudes into gun opening as seen
from front of machine.

3. Insert the male end of gun cable into the female

casting through opening in front panel. Make sure
connector is fully inserted and tighten knurled
screw.

4. Connect the gun trigger connector from the gun

and cable to the mating receptacle inside the
compartment located above the gun connection
made in item 3 above. Make sure that the key­ways are aligned, insert and tighten retaining ring.

SHIELDING GAS

(For Gas Metal Arc Welding Processes)
Customer must provide cylinder of appropriate type

shielding gas for the process being used.
A gas flow regulator, for CO2or 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.

2. Remove the cylinder cap. Inspect the cylinder

valves and regulator for damaged threads, dirt,
dust, oil or grease. Remove dust and dirt with a
clean cloth.

DO NOT ATTACH THE REGULATOR IF OIL,
GREASE OR DAMAGE IS PRESENT! Inform

your gas supplier of this condition. Oil or grease
in the presence of high pressure oxygen is
explosive.

----------------------------------------------------------------------

3. Stand to one side away from the outlet and open
the cylinder valve for an instant. This blows away
any dust or dirt which may have accumulated in
the valve outlet.

Be sure to keep your face away from the valve 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% CO2cylinder, insert
regulator adapter between regulator and cylinder
valve. If adapter is equipped with a plastic washer, be
sure it is seated for connection to the CO2cylinder.

5. Attach one end of the inlet gas hose to the outlet
fitting of the flow regulator, the other end to the
POWER MIG 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.

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.

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.

WARNING

WARNING

CYLINDER may explode if
damaged.

• Gas under pressure is explosive. Always keep
gas cylinders in an upright position and always
keep chained to undercarriage or stationary
support. See American National Standard Z-

49.1, “Safety in Welding and Cutting” pub­lished by the American Welding Society.

WARNING

WARNING

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SECTION B

OPERATION

SECTION B

POWER MIG 255C

TABLE OF CONTENTS

-OPERATION SECTION-

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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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B-2

OPERATION

B-2

POWER MIG 255C

Read entire Operation section before
operating the POWER MIG 255C.

ELECTRIC SHOCK can kill.

• Do not touch electrically live parts
or electrode with skin or wet
clothing. Insulate yourself from
work and ground.

• Always wear dry insulating
gloves.

FUMES AND GASES can be
dangerous.

• Keep your head out of fumes.

• Use ventilation or exhaust to
remove fumes from breathing
zone.

WELDING SPARKS can
cause fire or explosion.

• Keep flammable material away.

• Do not weld on closed containers.

ARC RAYS can burn eyes and
skin.

• Wear eye, ear and body protec­tion.

Observe all safety information throughout
this manual.

WARNING

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B-3

OPERATION

B-3

POWER MIG 255C

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. Asimple 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 CO2or 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.

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

The POWER MIG 255C WILL NOT operate
satisfactorily if powered with a portable or in-plant
generating system.

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WARNING

OPERATION

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 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-

mation also appears on the Procedure Decal on the
door inside the wire compartment.

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.

POWER MIG 255C

B-4B-4

FIGURE B.1— OPERATOR CONTROLS

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B-5

OPERATION

B-5

POWER MIG 255C

PROCEDURE FOR CHANGING
DRIVE AND IDLE ROLL SETS

1. Turn off the power source.

2. Release the pressure on the idle roll by swinging the
adjustable pressure arm down toward the back of
the machine. Lift the cast idle roll assembly and
allow it to sit in an upright position.

3. Remove the outside wire guide retaining plate by
loosening the two large knurled screws.

4. Twist the drive roll retaining mechanism to the

unlocked position 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.

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

To Mount a 30 Lb. (14 kg) Readi-Reel Package (Using the
Molded Plastic K363-P Readi-Reel Adapter:)

1. Open the Wire Drive Compartment Door

2. Depress the Release Bar on the Retaining Collar
and remove it from the spindle.

3. Place the Optional Adapter on the spindle

4. Re-install the Retaining Collar. Make sure that the
Release Bar "pops up" and that the collar retainers
fully engage the retaining ring groove on the spindle.

5. Rotate the spindle and adapter so the retaining spring is
at the 12 o'clock position.

6. Position the Readi-Reel so that it will rotate in a direction
when feeding so as to be de- reeled from top of the coil.

7. Set one of the Readi-Reel inside cage wires on the slot in
the retaining spring tab.

8. Lower the Readi-Reel to depress the retaining spring and
align the other inside cage wires with the grooves in the
molded adapter.

9. Slide cage all the way onto the adapter until the retaining
spring "pops up" fully.

CHECK TO BE SURE THE RETAINING SPRING HAS
FULLY RETURNED TO THE LOCKING POSITION AND
HAS SECURELY LOCKED THE READI-REEL CAGE IN
PLACE. RETAINING SPRING MUST REST ON THE CAGE,
NOT THE WELDING ELECTRODE.

---------------------------------------------------------------

10. To remove Readi-Reel from Adapter, depress

retaining spring tab with thumb while pulling the
Readi-Reel cage from the molded adapter with
both hands. Do not remove adapter from spindle.

To Mount 10 to 44 Lb. (4.5-20 kg) Spools (12"/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.

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.

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WARNING

2 IN. O.D.
SPINDLE

ADAPTER

RETAINING

SPRING

BRAKE

HOLDING

PIN

GROOVES

READI-REEL

INSIDE

CAGE

WIRES

RELEASE

BAR

RETAINING

COLLAR

B-6

OPERATION

B-6

POWER MIG 255C

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

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.

------------------------------------------------------------------------

NOTE: Check that drive rolls, guide plates, and gun
parts are proper for the wire size and type being used.
Refer to Table C.1 in Accessories section.

1. Turn the Readi-Reel or spool until the free end of
the electrode is accessible.

2. While securely holding the electrode, cut off the
bent end and straighten the first six inches. (If the
electrode is not properly straightened, it may not
feed properly through the wire drive system.)

3. Release the pressure on the idle roll by swinging
the adjustable pressure arm down toward the
back of the machine. Lift the cast idle roll 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.

IDLE ROLL PRESSURE SETTING

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.

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 between 1 and 3
Cored wires between 3 and 4
Steel, Stainless wires between 4 and 6

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.

WARNING

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WARNING

ALUMINUM

OUTER SHIELD

METALSHIELD
INNERSHIELD

STEEL

STAIN L ESS

COREDWIRES

SOLIDWIRES

6

1
3

2

5

4

FIGURE B.3

B-7

OPERATION

B-7

POWER MIG 255C

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.

7. Disconnect the shielding gas hose from the gun
bushing, if required.

8. Connect the shielding gas hose to the new gun
bushing, if required.

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.

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BUJE DEL RECEPTOR DEL ARMA

GUN RECEIVER BUSHING

DOUILLE DE RCEPTEUR DE PISTOLET

LOOSEN TIGHTEN

AFLOJE APRIETAN

DESSERREZ-VOUS SERRENT

TORNILLO DE PULGAR

THUMB SCREW

VIS DE POUCE

OUTER WIRE GUIDE

GUIDE DE CBLAGE EXTERNE

GUŒA DE ALAMBRE EXTERNA

SOCKET HEAD
CAP SCREW

VIS PRINCIPALE DE
LA DOUILLE CAP

TORNILLO DE CASQUILLO
DE LA CABEZA DE ZCALO

CONNECTOR BLOCK

BORNIER

BLOQUE DE CONECTADOR

FIGURE B.4

B-8

OPERATION

B-8

POWER MIG 255C

SETTING RUN-IN SPEED ON STAN­DARD POWER MIG FEEDER

FAST OR SLOW RUN-IN MODE
SELECTION,

(When Timer Option is not installed)

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.

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.

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.

4. The display will read "SLO run".

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.

On the initial trigger closure at power up, no output
power or wire feed will be available until the trigger is
opened and reclosed, regardless of wire feed speed
dial setting.

It is not necessary to repeat either of the above
procedures each time the unit is powered up. The unit
will remember the run-in mode from the previous

power down and return you to that same state upon
your next power up. Thus, you need only perform one
of the above procedures when you want to change the
run-in mode.

MAKING A WELD

1. Check that the electrode polarity is correct for the
process being used, then turn the power switch ON.

2. Set desired arc voltage and wire speed for the
particular electrode wire, material type and
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".

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B-9

OPERATION

B-9

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].

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.

AVOIDING WIRE FEEDING
PROBLEMS

Wire feeding problems can be avoided by observing
the following gun handling procedures:

a. Do not kink or pull cable around sharp corners.
b. 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.

e. Use only clean, rust-free electrode. The Lincoln

electrodes have proper surface lubrication.

f. Replace contact tip when the arc starts to become

unstable or the contact tip end is fused or
deformed.

g. Keep wire reel spindle brake tension to minimum

required to prevent excess reel over-travel which
may cause wire "loop-offs" from coil.

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

High Line V oltage — If the line voltage exceeds 125%

of rated input voltage, the output will be reduced to the
lower level to protect voltage rating of the capacitor
bank.

Low Line Voltage — You may not be able to get
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.

POWER MIG 255C

WARNING

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B-10

OPERATION

B-10

WELDING THERMAL OVERLOAD
PROTECTION

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.

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.

POWER MIG 255C

Note: See inside cover of machine for additional, commonly used welding procedure information.

70

80

90

100 110 120

English Wire Metric Wire

Length Part No. Size

1

Size

12' (3.6 m) K533-7 .035 – .045" 0.9 – 1.2 mm
15' (4.5 m) K533-3

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FIGURE B.5 — WELDING PROCEDURE INFORMATION

SECTION C

ACCESSORIES

SECTION C

POWER MIG 255C

TABLE OF CONTENTS

-ACCESSORIES SECTION-

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section C

Drive Roll Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

3/64 in. (1.2 mm) Aluminum Feeding Kit (K1703-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

K363P Readi-Reel Adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

Dual Cylinder Mounting Kit (K1702-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

Alternative Magnum GMAW Gun and Cable Assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

Magnum Gun Connection Kit (Optional K466-6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

Timer Kit Installation (Optional K1701-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

Operating Instructions for Timer Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

Connecting Spool Gun Adapter Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

Making a Weld with the Spool Gun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4

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C-2

ACCESSORIES

C-2

POWER MIG 255C

DRIVE ROLL KITS

Refer to Table C.1 for various drive roll kits that are available for
the POWER MIG. All items in Bold are supplied standard with the
POWER MIG.

TABLE C.1 — AVAILABLE DRIVE ROLL KITS.

3/64" (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.

spool.

K363P READI-REEL ADAPTER

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

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:

MAGNUM GUN CONNECTION KIT
(Optional K466-6)

Using the optional K466-6 Magnum Connection kit for
the POWER MIG permits use of standard Magnum
200, 300 or 400 gun and cable assemblies.

TIMER KIT INSTALLATION (Optional
K1701-1)

The timer kit adds selectable 4-step trigger interlock,
spot and Run-In functions and manual adjustment of
burnback time. Install as follows, or per the
instructions included with the kit:

Remove all input power to the POWER MIG 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.

3. Remove the lower cover panel from the front of the
machine by removing the two screws which secure

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.

WARNING

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Electrode Type Wire Size Drive Roll Kit

Solid Steel

.023”-.030” (0.6-0.8 mm)

KP1696-030S
.035” (0.9 mm) KP1696-035S
.045” (1.2 mm) KP1696-045S

.035-.045 (0.9-1.2mm) KP1696-1

.040 (1.01) KP1696-2

Cored

.035” (0.9 mm) KP1697-035C
.045” (1.2 mm) KP1697-045C

Aluminum

3/64” (1.2 mm) KP1695-3/64A

(Includes
Stainless
Steel)

English Wire Metric Wire

Length Part No. Size

1

Size

12' (3.6 m) K533-7 .035 – .045" 0.9 – 1.2 mm
15' (4.5 m) K533-3

C-3

ACCESSORIES

C-3

POWER MIG 255C

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.

-----------------------------------------------------------------------

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.

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WARNING

C-4

ACCESSORIES

C-4

POWER MIG 255C

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MAKING A WELD WITH THE
PRINCE XL SPOOL GUN

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.

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.
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.

CAUTION

FIGURE C.1

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:

5. To return to normal POWER MIG 255C welding,
release the spool gun trigger and reset feeder gun
voltage procedure setting if necessary.

MAKING A WELD WITH THE
MAGNUM SG SPOOL GUN

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.

Wire Diameter

In. (mm)

.030” (.8mm)
.035” (.9mm)

3/64” (1.2mm)

Wire Feed Speed

Display

270
250
240

Arc voltage

Setting

15V
16V
20V

7-PIN
SPOOL GUN
RECEPTACLE

K2445-1
CABLE ADAPTER
(7-pin to 6-pin)

+

Note: This adapter is only
for The Magnum SG
Spool Gun.

GAS LINE
AND 5/8 FITTING

+ POSITIVE
CABLE AND STUD

C-5

ACCESSORIES

C-5

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.

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.

See the following procedure for setting the Wire Speed Feed
using the Magnum SG Spool Gun:

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

CAUTION

Wire Feed Speed

Display

50
300
700

SG Spool Gun Wire Feed Speed

Approximate Range

50-200
200-400
300-600

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C-6

NOTES

POWER MIG 255

C-6

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SECTION D

MAINTENANCE

SECTION D

POWER MIG 255C

TABLE OF CONTENTS

-MAINTENANCE SECTION-

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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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D-2

MAINTENANCE

D-2

POWER MIG 255C

SAFETY PRECAUTIONS

• 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.

• Unplug the power cable if it is connected to a
receptacle.

------------------------------------------------------------------------

GENERAL MAINTENANCE

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.

DRIVE ROLLS AND GUIDE PLATES

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.

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.

For instructions on replacing or changing drive roll, see
"Wire Drive Rolls" in Operation section.

CONTACT TIP AND GAS NOZZLE
INSTALLATION

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.

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.

WARNING

1. Be sure the nozzle insulator is fully screwed onto the
gun tube and does not block the gas holes in the dif­fuser.

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.

GUN TUBES AND NOZZLES

a. Replace worn contact tips as required.
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.

Excessive pressure at the start may cause the dirt
to form a plug.

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.

LINER REMOVAL AND REPLACEMENT

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

.

CAUTION

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