Lincoln Electric POWER MIG 255XT User manual

POWER MIG®255XT IMT977
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
PRE AUTIONS ONTAINED THROUGHOUT. And, most importantly, think
before you act and be careful.
OPERATOR’S MANUAL
For use with machines Code numbers:
11519, 11520
Please Examine Carton and Equipment For Damage Immediately
When this equipment is shipped, title passes to the purchaser upon receipt by
the carrier. onsequently, laims for material damaged in shipment must be
made by the purchaser against the transportation company at the time the
shipment is received.
Please record your equipment identification information below for future refer-
ence. This information can be found on your machine nameplate.
Product ________________________
Model Number _____________________
ode Number or Date ode_________________
Serial Number_______________________
Date Purchased_______________________________
Where Purchased______________________
Whenever you request replacement parts or information on this equipment,
always supply the information you have recorded above. The code number is
especially important when identifying the correct replacement parts.
This manual covers equipment which is no
longer in production by The Lincoln Electric Co.
Specications and availability of optional
features may have changed.

ARC WELDIN CAN BE HAZARDOUS. PROTECT YOUR-
SELF AND OTHERS FROM POSSIBLE SERIOUS INJURY
OR DEATH. KEEP CHILDREN AWAY. PACEMAKER WEAR-
ERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE
OPERATIN .
Read and understand the following safety highlights. For
additional safety information, it is strongly recommended
that you purchase a copy of “Safety in Welding & utting -
ANSI Standard Z49.1”
BE SURE THAT ALL INSTALLATION, OPERA-
TION, MAINTENANCE AND REPAIR PROCE-
DURES ARE PERFORMED ONLY BY QUALIFIED
INDIVIDUALS.
WARNIN
ARC RAYS can burn.
2.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 weld-
ing. Headshield and filter lens should
conform to ANSI Z87. I standards.
2.b. Use suitable clothing made from durable flame-resis-
tant material to protect your skin and that of your
helpers from the arc rays.
2.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.
FOR ELECTRICALLY
powered equipment.
1.a. Turn off input power using the discon-
nect switch at the fuse box before
working on the equipment.
1.b. Install equipment in accordance with the U.S.
National Electrical ode, all local codes and the man-
ufacturer’s recommendations.
1.c. Ground the equipment in accordance with the U.S.
National Electrical ode and the manufacturer’s rec-
ommendations.
SAFETY
MAR95
SAFETY
WELDIN SPARKS can
cause fire or explosion.
4.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.
4.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
utting” (ANSI Standard Z49.1) and the operating
information for the equipment being used.
4.c. When not welding, make certain no part of the elec-
trode circuit is touching the work or ground.Accidental
contact can cause overheating and create a fire haz-
ard.
4.d. Do not heat, cut or weld tanks, drums or containers
until the proper steps have been taken to insure that
such procedures will not cause flammable or toxic
vapors from substances inside. They can cause an
explosion even though they have been “cleaned”. For
information, purchase “Recommended Safe Practices
for the Preparation for Welding and utting of
ontainers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding
Society (see address above).
4.e. Vent hollow castings or containers before heating,
cutting or welding. They may explode.
4.f.
Sparks and spatter are thrown from the welding arc.
Wear oil free protective garments such as leather
gloves, heavy shirt, cuffless trousers, high shoes and
a cap over your hair. Wear ear plugs when welding
out of position or in confined places. Always wear
safety glasses with side shields when in a welding
area.
4.g. onnect 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 weld-
ing 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.
4.h. Read and follow NFPA 51B “ Standard for Fire
Prevention During Welding, utting and Other Hot
Work”, available from NFPA,1 Batterymarch Park,PO
box 9101, Quincy, Ma 022690-9101.
4.i. Do not use a welding power source for pipe thawing.
SAFETY
WELDIN SPARKS can
cause fire or explosion.
4.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.
4.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
utting” (ANSI Standard Z49.1) and the operating
information for the equipment being used.
4.c. When not welding, make certain no part of the elec-
trode circuit is touching the work or ground.Accidental
contact can cause overheating and create a fire haz-
ard.
4.d. Do not heat, cut or weld tanks, drums or containers
until the proper steps have been taken to insure that
such procedures will not cause flammable or toxic
vapors from substances inside. They can cause an
explosion even though they have been “cleaned”. For
information, purchase “Recommended Safe Practices
for the Preparation for Welding and utting of
ontainers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding
Society (see address above).
4.e. Vent hollow castings or containers before heating,
cutting or welding. They may explode.
4.f.
Sparks and spatter are thrown from the welding arc.
Wear oil free protective garments such as leather
gloves, heavy shirt, cuffless trousers, high shoes and
a cap over your hair. Wear ear plugs when welding
out of position or in confined places. Always wear
safety glasses with side shields when in a welding
area.
4.g. onnect 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 weld-
ing 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.
4.h. Read and follow NFPA 51B “ Standard for Fire
Prevention During Welding, utting and Other Hot
Work”, available from NFPA,1 Batterymarch Park,PO
box 9101, Quincy, Ma 022690-9101.
4.i. Do not use a welding power source for pipe thawing.
SAFETY
WELDIN SPARKS can
cause fire or explosion.
4.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.
4.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
utting” (ANSI Standard Z49.1) and the operating
information for the equipment being used.
4.c. When not welding, make certain no part of the elec-
trode circuit is touching the work or ground.Accidental
contact can cause overheating and create a fire haz-
ard.
4.d. Do not heat, cut or weld tanks, drums or containers
until the proper steps have been taken to insure that
such procedures will not cause flammable or toxic
vapors from substances inside. They can cause an
explosion even though they have been “cleaned”. For
information, purchase “Recommended Safe Practices
for the Preparation for Welding and utting of
ontainers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding
Society (see address above).
4.e. Vent hollow castings or containers before heating,
cutting or welding. They may explode.
4.f.
Sparks and spatter are thrown from the welding arc.
Wear oil free protective garments such as leather
gloves, heavy shirt, cuffless trousers, high shoes and
a cap over your hair. Wear ear plugs when welding
out of position or in confined places. Always wear
safety glasses with side shields when in a welding
area.
4.g. onnect 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 weld-
ing 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.
4.h. Read and follow NFPA 51B “ Standard for Fire
Prevention During Welding, utting and Other Hot
Work”, available from NFPA,1 Batterymarch Park,PO
box 9101, Quincy, Ma 022690-9101.
4.i. Do not use a welding power source for pipe thawing.
SAFETY
WELDIN SPARKS can
cause fire or explosion.
4.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.
4.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
utting” (ANSI Standard Z49.1) and the operating
information for the equipment being used.
4.c. When not welding, make certain no part of the elec-
trode circuit is touching the work or ground.Accidental
contact can cause overheating and create a fire haz-
ard.
4.d. Do not heat, cut or weld tanks, drums or containers
until the proper steps have been taken to insure that
such procedures will not cause flammable or toxic
vapors from substances inside. They can cause an
explosion even though they have been “cleaned”. For
information, purchase “Recommended Safe Practices
for the Preparation for Welding and utting of
ontainers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding
Society (see address above).
4.e. Vent hollow castings or containers before heating,
cutting or welding. They may explode.
4.f.
Sparks and spatter are thrown from the welding arc.
Wear oil free protective garments such as leather
gloves, heavy shirt, cuffless trousers, high shoes and
a cap over your hair. Wear ear plugs when welding
out of position or in confined places. Always wear
safety glasses with side shields when in a welding
area.
4.g. onnect 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 weld-
ing 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.
4.h. Read and follow NFPA 51B “ Standard for Fire
Prevention During Welding, utting and Other Hot
Work”, available from NFPA,1 Batterymarch Park,PO
box 9101, Quincy, Ma 022690-9101.
4.i. Do not use a welding power source for pipe thawing.
SAFETY
WELDIN SPARKS can
cause fire or explosion.
4.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.
4.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
utting” (ANSI Standard Z49.1) and the operating
information for the equipment being used.
4.c. When not welding, make certain no part of the elec-
trode circuit is touching the work or ground.Accidental
contact can cause overheating and create a fire haz-
ard.
4.d. Do not heat, cut or weld tanks, drums or containers
until the proper steps have been taken to insure that
such procedures will not cause flammable or toxic
vapors from substances inside. They can cause an
explosion even though they have been “cleaned”. For
information, purchase “Recommended Safe Practices
for the Preparation for Welding and utting of
ontainers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding
Society (see address above).
4.e. Vent hollow castings or containers before heating,
cutting or welding. They may explode.
4.f.
Sparks and spatter are thrown from the welding arc.
Wear oil free protective garments such as leather
gloves, heavy shirt, cuffless trousers, high shoes and
a cap over your hair. Wear ear plugs when welding
out of position or in confined places. Always wear
safety glasses with side shields when in a welding
area.
4.g. onnect 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 weld-
ing 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.
4.h. Read and follow NFPA 51B “ Standard for Fire
Prevention During Welding, utting and Other Hot
Work”, available from NFPA,1 Batterymarch Park,PO
box 9101, Quincy, Ma 022690-9101.
4.i. Do not use a welding power source for pipe thawing.

SAFETY
WELDIN SPARKS can
cause fire or explosion.
4.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.
4.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
utting” (ANSI Standard Z49.1) and the operating
information for the equipment being used.
4.c. When not welding, make certain no part of the elec-
trode circuit is touching the work or ground.Accidental
contact can cause overheating and create a fire haz-
ard.
4.d. Do not heat, cut or weld tanks, drums or containers
until the proper steps have been taken to insure that
such procedures will not cause flammable or toxic
vapors from substances inside. They can cause an
explosion even though they have been “cleaned”. For
information, purchase “Recommended Safe Practices
for the Preparation for Welding and utting of
ontainers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding
Society (see address above).
4.e. Vent hollow castings or containers before heating,
cutting or welding. They may explode.
4.f.
Sparks and spatter are thrown from the welding arc.
Wear oil free protective garments such as leather
gloves, heavy shirt, cuffless trousers, high shoes and
a cap over your hair. Wear ear plugs when welding
out of position or in confined places. Always wear
safety glasses with side shields when in a welding
area.
4.g. onnect 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 weld-
ing 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.
4.h. Read and follow NFPA 51B “ Standard for Fire
Prevention During Welding, utting and Other Hot
Work”, available from NFPA,1 Batterymarch Park,PO
box 9101, Quincy, Ma 022690-9101.
4.i. Do not use a welding power source for pipe thawing.

ELECTRIC SHOCK can kill.
5.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 cloth-
ing. Wear dry, hole-free gloves to
insulate hands.
5.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 fol-
lowing equipment:
• Semiautomatic DC Constant Voltage (Wire)
Welder.
• DC Manual (Stick) Welder.
• AC Welder with Reduced Voltage Control.
5.c. In semiautomatic or automatic wire welding, the elec-
trode, electrode reel, welding head, nozzle or semi-
automatic welding gun are also electrically “hot”.
5.d. Always be sure the work cable makes a good electri-
cal connection with the metal being welded. The con-
nection should be as close as possible to the area
being welded.
5.e. Ground the work or metal to be welded to a good
electrical (earth) ground.
5.f. Maintain the electrode holder, work clamp, welding
cable and welding machine in good, safe operating
condition. Replace damaged insulation.
5.g. Never dip the electrode in water for cooling.
5.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.
5.i. When working above floor level, use a safety belt to
protect yourself from a fall should you get a shock.
5.j. Also see Items 4.c. and 1.
SAFETY

FUMES AND ASES
can be dangerous.
6.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 ventila-
tion 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 con-
tainer 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.
6. 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 there-
after to be certain it is within applicable OSHA PEL
and A GIH TLV limits.
6.c. Do not weld in locations near chlorinated hydrocarbon
vapors coming from degreasing, cleaning or spray-
ing operations. The heat and rays of the arc can
react with solvent vapors to form phosgene, a high-
ly toxic gas, and other irritating products.
6.d. Shielding gases used for arc welding can displace air
and cause injury or death. Always use enough venti-
lation, especially in confined areas, to insure breath-
ing air is safe.
6.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.
SAFETY

CYLINDER may explode if
damaged.
7.a. Use only compressed gas cylinders
containing the correct shielding gas for
the process used and properly operat-
ing 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. ylinders should be located:
•Away from areas where they may be struck or sub-
jected to physical damage.
•A safe distance from arc welding or cutting opera-
tions 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 con-
nected for use.
7.g. Read and follow the instructions on compressed gas
cylinders, associated equipment, and GA publica-
tion P-l, “Precautions for Safe Handling of
ompressed Gases in ylinders,” available from the
ompressed Gas Association 1235 Jefferson Davis
Highway, Arlington, VA 22202.
SAFETY
This statement appears where the information must be fol-
lowed exactly to avoid serious personal injury or loss of
life.
WARNIN
This statement appears where the information must be fol-
lowed to avoid minor personal injury or damage to this
equipment.
CAUTION

TABLE OF CONTENTS
Page
Installation................................................................Section A
Technical Specifications................................................A-1
Safety Precautions........................................................A-2
Uncrating the POWER MIG® 255XT............................A-2
Location ........................................................................A-2
Input Power, Grounding and connection DiagramsA-2/A-4
Output polarity onnections..........................................A-5
Gun and able Installation............................................A-5
Shielding Gas .........................................................A-6,A-7
Operation..................................................................Section B
Safety Precautions .......................................................B-1
Product Description.......................................................B-2
Recommended Processes and Equipment...................B-2
Welding apability.........................................................B-3
Limitations.....................................................................B-3
Description of ontrols..................................................B-3
Wire drive Roll...............................................................B-3
Wire Size onversion Parts..........................................B-4
Procedure for hanging Drive Roll...............................B-4
Wire Reel Loading..................................................B-4,B-5
Mounting of 10 to 30 lbs. Spools ..................................B-5
To Start the Welder .......................................................B-6
Feeding Electrode.........................................................B-6
Idle Roll Pressure Setting..............................................B-7
Wire Drive onfiguration .......................................B-8, B-9
Setting Run-in Speed..................................................B-10
Operating Instructions for Timer Setting............B-11, B-12
Making a Weld.............................................................B-13
Avoiding Wire Feeding Problems................................B-14
Fan ontrols................................................................B-15
Input Line Voltage Protection......................................B-15
Wire Feed Overload Protection...................................B-15
Welding Thermal Overload Protection ........................B-16
Overcurrent Protection................................................B-16
Welding Procedure Information...................................B-16
Accessories..............................................................Section C
Drive Rolls Kits.............................................................. -1
Aluminium Feeding Kit ................................................. -1
K363P Readi-Reel Adapter........................................... -1
Dual ylinder Mounting Kit .......................................... -1
Alternative Magnum GMAW Gun and able
Assemblies............................................................ -2
Magnum Gun onnection Kit ....................................... -2
Spool Gun .................................................................... -3
onnecting the Spool Gun............................................ -3
Making a Weld with the Spool Gun Adapter Kit and
Spool Gun Installed....................................... -4, -5
Magnum SG Spool Gun........................................ -5, -6
Magnum 250LX Push-Pull
and Push-Pull Adapter ................................. -7, -8, -9

TABLE OF CONTENTS
Page
Maintenance.............................................................Section D
Safety Precautions .........................................................D-1
General Maintenence .....................................................D-1
Drive Rolls and Guide Tubes..........................................D-1
ontact Tip and gas Nozzle Installation.........................D-1
Gun Tubes and Nozzles.................................................D-2
able leaning...............................................................D-2
Liner removal and Replacement..............................D-3,D-4
Gun Handle Disassembly...............................................D-5
Troubleshooting.......................................................Section E
How to Use Troubleshooting Guide................................E-1
Troubleshooting Guide....................................................E-2
Troubleshooting Guide....................................................E-3
Troubleshooting Guide....................................................E-4
Diagrams ..................................................................Section F
Parts Manual .............................................................P Series
POWER MIG® 255XT.....................................P-579 Series
Magnum 250L Gun................................................P202-H.2

TECHNICAL SPECIFICATIONS
Height Width Depth Weight
31.79 in 18.88 in 38.78 in 220 Ibs
808 mm 480 mm 985 mm 100 kg
Wire Speed 50 - 700 IPM (1.27 - 17.8 m/min)
INPUT – SIN LE PHASE ONLY
RATED OUTPUT
OUTPUT
RECOMMENDED INPUT WIRE AND FUSE SIZES
PHYSICAL DIMENSIONS
WIRE SPEED RAN E
Standard
Voltage/Frequency
208/230/60 Hz
230/460/575/60Hz
Duty Cycle
40%
60%
100%
Amps
250 Amps
200 Amps
145 Amps
Volts at rated
Amperes
26 Volts
28 Volts
26 Volts
Welding Current
Range (Continuous)
30 - 300 Amps
Maximum
Open Circuit
Voltage
40 Volts
Welding
Voltage Range
10-28 Volts
Input Current @ 200
Amp Rated Output
*47/44 Amps
41/20/16 Amps
Input Current @ 250
Amp Rated Output
*56/52
50/24/19
Input Voltage
Frequency (Hz)
208/60
230/60
460/60
575/60
Fuse or breaker
Size (Super Lag)
60
60
30
25
Input Ampere
Rating On
Nameplate
56
52
24
19
75oC Copper Wire in
Conduit AW (IEC) Sizes
(For lengths up to 100 ft.)
8 (10 mm2)
10 (6 mm2)
14 (2.5 mm2)
14 (2.5 mm2)
75oC Copper Wire in
Conduit AW (IEC) Sizes
(For lengthsexceding 100 ft.)
6 (16 mm2)
8 (10 mm2)
12 (4 mm2)
12 (4 mm2)
*With 115V receptacle loaded to 15A.

INSTALLATION
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 MI ® 255XT
Operating
Manual should install and operate this
equipment.
• Machine must be grounded per any national,
local or other applicable electrical
codes.
• The POWER MI power switch is to be in
the OFF position when installing work
cable and gun and when connecting other
equipment.
-----------------------------------------------------------------------
UNCRATIN THE POWER MI ® 255XT
ut banding and lift off cardboard carton. ut 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.
INPUT POWER, ROUNDIN AND
CONNECTION DIA RAMS
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts such
as output terminals or internal wiring.
• All input power must be electrically dis-
connected before proceeding.
-----------------------------------------------------------------------------------------
WARNIN
WARNIN

INSTALLATION
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 volt-
age, amperes, phase, and frequency specified on
the welder nameplate. Also be sure the planned
installation will meet the U.S. National Electrical
ode and local code requirements. This welder
may be operated from a single phase line or from
one phase of a three phase line.
2. Models that have multiple input voltages specified
on the nameplate (e.g. 208/230) are shipped con-
nected for the highest voltage. If the welder is to be
operated on lower voltage, it must be 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.
FI URE 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 connect-
ed to the welder. Obtain a receptacle and mount it
in a suitable location. 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.
WARNIN

4. Using the instructions in Figure A.3, have a quali-
fied electrician connect the receptacle or cable to
the input power lines and the system ground per
the U.S. National Electrical ode and any applica-
ble 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.
FI URE A.2 — Triple Voltage Machine Input
Connections
FI URE A.3 —Receptacle Diagram
INSTALLATION
ONNE T TO A
SYSTEM GROUNDING
WIRE. SEE THE
UNITED STATES
NATIONAL
ELE TRI AL
ODE AND/OR LO AL
ODES FOR OTHER
DETAILS AND MEANS
FOR PROPER
GROUNDING.
ONNE T 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 and
the work lead, which is attached to the work clamp, is
to be connected to the positive (+) labeled terminal.
UN AND CABLE INSTALLATION
The Magnum 250L gun and cable provided with the
POWER MIG® 255XT is factory installed with a liner
for .035-.045" (0.9-1.2 mm) electrode and an .035"
(0.9 mm) contact tip. Install the .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. onnect the gun trigger connector from the gun
and cable to the mating receptacle inside the com-
partment located above the gun connection made
in item 3 above. Make sure that the keyways are
aligned, insert and tighten retaining ring.
INSTALLATION
WARNIN

SHIELDIN AS
(For Gas Metal Arc Welding Processes)
ustomer must provide cylinder of appropriate type
shielding gas for the process being used.
Agas flow regulator, for O 2orArgon blend gas, and
an inlet gas hose are factory provided with the
POWER MIG® 255XT.
CYLINDER may explode if
damaged.
• as 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.
Install shielding gas supply as follows:
1. Set gas cylinder on rear platform of POWER MIG®
255XT. 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 ATTA H 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.
INSTALLATION
WARNIN
WARNIN

NOTE: If connecting to 100% O2cylinder, 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 O2cylinder.
5. Attach one end of the inlet gas hose to the outlet
fitting of the flow regulator, the other end to the
POWER MIG® 255XT 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 ircuit Breaker. The
receptacle is UL and SA approved.
INSTALLATION
WARNIN

OPERATION
Read entire Operation section before
operating the POWER MI ® 255XT.
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 ASES can be
dangerous.
• Keep your head out of
fumes.
• Use ventilation or exhaust
to remove fumes from
breathing zone.
----------------------------------------------------------------------
WELDIN 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.
WARNIN

PRODUCT DESCRIPTION
The POWER MIG® 255XT is a complete semiautomatic
constant voltage D arc welding machine built to meet
NEMA specifications. It combines a constant voltage power
source and a constant speed wire feeder with a
microcomputer-based controller to form a reliable high-
performance welding system. A simple control scheme,
consisting of continuous full range voltage and wire feed
speed controls, provides versatility with ease of use and
accuracy. The POWER MIG® 255XT 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 O2or 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. (3.1 m) power cable with plug and a
10ft. (3.1 m) work cable with clamp.
The POWER MIG® 255XT features a Timer kit that provides
variable burnback control, a spot function, a selectable 4-
step trigger interlock and adjustable "Run In" for wire starting
optimization is availiable. Optional features include a Dual
ylinder Mounting kit and an Aluminum Feeding Kit for push
feeding with standard built in feeder.
RECOMMENDED PROCESSES AND
EQUIPMENT
The POWER MIG® 255XT 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® and Ultracore® ; as well as .035" (0.9 mm) and
.045" (1.2 mm) Innershield®self-shielding electrodes.
The POWER MIG® 255XT 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.
OPERATION

OPERATION
WELDIN CAPABILITY
The POWER MIG® 255XT 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® 255XT WILL NOT operate
satisfactorily if powered with a portable or in-plant
generating system.
DESCRIPTION OF CONTROLS
Power ON/OFF Switch — Place the lever in the
"ON" position to energize the POWER MIG® 255XT.
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®
255XT 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 match-
es. See "Procedure for hanging Drive Roll" in this
section. This information also appears on the
Procedure Decal on the door inside the wire com-
partment.

OPERATION
WIRE SIZE CONVERSION PARTS
The POWER MIG® 255XT 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.
PROCEDURE FOR CHAN IN
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.1)
FIGURE B.1
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 nec-
essary.
WIRE REEL LOADIN - READI
REELS, SPOOLS OR COILS
To Mount a 30 Lb. (14 kg) Readi-Reel Package
(Using the Molded Plastic K363-P Readi-Reel
Adapter:)

OPERATION
1. Open the Wire Drive ompartment Door
2. Depress the Release Bar on the Retaining ollar
and remove it from the spindle.
3. Place the Optional Adapter on the spindle
4. Re-install the Retaining ollar. 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 RETAININ SPRIN
HAS FULLY RETURNED TO THE LOCKIN
POSITION AND HAS SECURELY LOCKED THE
READI-REEL CA E IN PLACE. RETAININ
SPRIN MUST REST ON THE CA E, NOT THE
WELDIN 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.
WARNIN
A
2 IN. O.D.
SPINDLE ADAPTER
RETAINING
SPRING
BRAKE
HOLDING
PIN GROOVES
READI-REEL
INSIDE
CAGE
WIRES RELEASE
BAR
RETAINING
COLLAR