058-9305-6
MIG 140 INVERTER WELDER
INSTRUCTION MANUAL
Quick Start Guide
If any parts are
missing or damaged,
or if you have any
questions, please call
1-800-689-9928.
Read and understand this instruction manual
thoroughly before using the product. It contains
important information for your safety, as well as
operating and maintenance advice.
Keep this instruction manual for future use. Should
this product be passed on to a third party, this
instruction manual must be included.
MIG 140 INVERTER WELDER 058-9305-6
QUICK START GUIDE
MIG 140 INVERTER WELDER 058-9305-6
MIG welding
STEP 1
Installing the wire
Remove the nozzle (1) and contact tip (2) from
the end of the torch assembly. Place the spool
on the hub with the wire passing from the
bottom of spool into the drive mechanism.
pages 23-25, steps 1-22
STEP 2
Setting the wire tension
Press the trigger on the gun. Turn the drive
tension adjustment knob (1) clockwise, and
increase the drive tension until the wire feeds
smoothly without slipping.
page 26, steps 1-2
MC-589305-15
1
2
MC-589306-12
MC-589305-09
IGBT INVERTER WIRE FEED WELDER
SOUDEUSE DEVIDOIR INVERSEUR IGBT
4
56
7
8
9
10
V
V
POWER
ALIMENTATION
SPOOL GUN
PISTOLET À BOBINE
MIG/MIG
STICK/BAGUETTE 4-STEP
TEST GAS
WIRE
FIL
V
WORK
MARCHE
ALARM
MD
4
56
7
8
9
10
MIG/MIG
2-STEP
058-9305
MX MIG 140 INVERTER
1
STEP 3
Operation
Hold the torch in one hand and set the wire
speed control with the other hand to its
maximum position. Pull the trigger (1) on the
torch to start an arc. Drag the torch on the
work piece while simultaneously turning the
wire speed control counterclockwise.
pages 30-31, steps 3-5
page 32 (refer to welding techniques)
Stick welding
STEP 1
Plug in the electrode holder cable (1) into the
electrode cable connection and attach the
electrode (2) in the electrode holder (3).
pages 19-20, steps 1-3
MC-589305-27
1
IGBT INVERTER WIRE FEED WELDER
SOUDEUSE DEVIDOIR INVERSEUR IGBT
4
56
7
8
9
10
V
V
POWER
ALIMENTATION
SPOOL GUN
PISTOLET À BOBINE
MIG/MIG
STICK/BAGUETTE 4-STEP
TEST GAS
WIRE
FIL
V
WORK
MARCHE
ALARM
MD
4
56
7
8
9
10
MIG/MIG
2-STEP
058-9305
MX MIG 140 INVERTER
2
MC-589305-05
1
3
STEP 2
Plug in the power cord. Turn the Spool gun/
MIG selector (1) to the stick welding mode.
page 20, step 5-6
STEP 3
Operation
Strike an arc by scratching the work piece (1)
with the electrode (2) and raising it by 1/8"
and maintain the gap throughout the weld.
page 37, steps 1-5
MC-589306-12
MC-589305-09
IGBT INVERTER WIRE FEED WELDER
SOUDEUSE DEVIDOIR INVERSEUR IGBT
4
56
7
8
9
10
V
V
POWER
ALIMENTATION
SPOOL GUN
PISTOLET À BOBINE
MIG/MIG
STICK/BAGUETTE 4-STEP
TEST GAS
WIRE
FIL
V
WORK
MARCHE
ALARM
MD
4
56
7
8
9
10
MIG/MIG
2-STEP
058-9305
MX MIG 140 INVERTER
1
MC-589306-12
MC-589305-39
1/8"
1
2
TABLE OF CONTENTS
2
MIG 140 INVERTER WELDER 058-9305-6
QUICK START GUIDE
TECHNICAL SPECIFICATIONS 3–4
SAFETY GUIDELINES 5–9
KEY PARTS DIAGRAM 10–11
IMPORTANT INFORMATION 12–18
ASSEMBLY INSTRUCTIONS 19–28
OPERATING INSTRUCTIONS 29–42
MAINTENANCE 43
TROUBLESHOOTING 44–45
MAIN CIRCUIT CHART 46
EXPLODED VIEW 47
PARTS LIST 48
WARRANTY 49–50
TECHNICAL SPECIFICATIONS
3
MIG 140 INVERTER WELDER 058-9305-6
WELDER SPECIFICATION
POWER SUPPLY Single phase, 120 V, 60 Hz
MIG WELDING CURRENT 30–140 A DC
RATED INPUT CURRENT 20 A
RATED INPUT CAPACITANCE 2.4 KVA
NO-LOAD VOLTAGE 69 V
RATED WORKING VOLTAGE 18.5 V
RATED DUTY CYCLE 30%
EFFICIENCY 85%
POWER FACTOR 0.75
INSULATION CLASS H
ENCLOSURE PROTECTION IP 21 S
COOLING TYPE FAN COOLED
WIRE USED 0.023-0.035"
(0.58
-
0.89 mm)
MIG wire
0.030-0.035"
(0.76
-
0.89 mm)
flux-core wire
WIRE DIAMETER 0.023"
(0.58 mm)
, 0.030"
(0.76 mm)
,
0.035"
(0.89 mm)
ELECTRODE DIAMETER 1/16"
(1.58 mm)
, 5/64"
(1.98 mm)
DIMENSIONS (L x W x H) 21 39/64 x 12 39/64 x 17 19/64"
(55 x 32 x 44 cm)
WEIGHT 39 lb 8 oz
(17.93 kg)
TECHNICAL SPECIFICATIONS
4
MIG 140 INVERTER WELDER 058-9305-6
CURRENT SPECIFICATION
SPOOL GUN (OPTIONAL) SPECIFICATION
DUTY CYCLE/TIME 10 MINUTES
WELDING CURRENT (IN AMPS)
30
%
90
100
%
49
CONNECTOR 4-pin quick connect power connection
MOTOR VOLTAGE 24 V DC
WIRE SPEED 590"/min
RATING 90 A w/CO2 gas
65 A A/Ar gas
SAFETY GUIDELINES
5
MIG 140 INVERTER WELDER 058-9305-6
This manual contains information that relates to PROTECTING PERSONAL SAFETY and PREVENTING
EQUIPMENT PROBLEMS. It is very important to read this manual carefully and understand it
thoroughly before using the product. The symbols listed below are used to indicate this information.
Note – The word “Note” is used to inform the
reader of something he/she needs to know about
the tool.
PERSONAL SAFETY
These precautions are intended for the personal safety of the user and others working with the user.
Please take time to read and understand them.
DANGER!
Potential hazard that will result in serious
injury or loss of life.
WARNING!
Potential hazard that could result in
serious injury or loss of life.
CAUTION!
Potential hazard that may result in
moderate injury or damage to equipment.
SAFETY GUIDELINES
6
MIG 140 INVERTER WELDER 058-9305-6
DANGER!
Potential hazard that will result in serious injury or loss of life.
•Keep children or other personnel away from the work area while welding. Do
not allow children or persons with mental or physical disabilities to handle
the welder.
•Do not use the welder in the presence of flammable liquids or gases. Sparks
that are created during use may ignite gases.
• Always ensure that a fire extinguisher is available in adequate distance
within the welding environment.
• Have the welder repaired by a qualified technician in accordance with local,
state and national codes.
• Do not repair or maintain the welder while the power is on.
• Do not use an ungrounded power source, as it might cause electrical shock
to the user.
• The welding process must conform to ANSI Z49.1; NFPA 51; OSHA 29 CFR,
part 1910, sub part Q; CSA W117.2; American Welding Society standard A6.0.
• Do not expose the welder to rain.
• Always disconnect the power supply when working on internal components.
• Do not touch the PC board without being properly grounded with a wrist
strap. Place the PC board in a static proof bag while shipping.
• Make sure harmful arc rays are shielded from view of other personnel.
•Risk of electric shock: Do not touch electrical live parts or metal
components connected to the welding wire, as doing so may cause fatal
shock and severe burns. Secure the ground lead before welding. Poor ground
connection creates hazardous situation. Wear dry protective apparel like coat,
shirt, gloves, and insulated footwear.
•Risk of explosion: Keep high pressure shielding gas cylinder away from
welding or electrical circuits. Never expose cylinders to high heat, sparks,
open flames, mechanical shocks or arcs. Do not touch the cylinder with MIG
gun and do not weld on the cylinder. Use proper regulators, gas hoses and
fittings for the specific application. Use protective cylinder cap whenever
possible.
SAFETY GUIDELINES
7
MIG 140 INVERTER WELDER 058-9305-6
•Risk for breathing: Never directly inhale the emission of harmful fumes
during welding. Make sure the work area is clean, dry and ventilated. Use a
ventilation device to remove welding fumes from the work environment.
• Do not weld on coated materials like galvanized, cadmium plated or
contacting zinc, mercury, or barium, as they emit harmful fumes that are
dangerous to breathe. If required, use a respirator with air supply or remove
coating from the material in the weld area.
• Do not weld near materials that will emit toxic fumes when heated. Vapours
from cleaners, sprays, and degreasers can be highly toxic when heated.
•Risk of fire: Do not weld on containers or pipes that contain flammable,
gaseous, or liquid combustibles. Welding creates sparks and heat that ignite
flammable and explosive materials. Remove all flammable materials within
35 feet of the welding arc or tightly cover the flammable materials with
fireproof covers. Ensure that flying sparks do not cause fires or explosions in
hidden areas, cracks or areas that are out of vision. Use a fire extinguisher in
the work area. Do not have any items that are combustible, such as lighters
or matches
•Connect the work lead to the weld area as close as possible to prevent any
unknown, unintended paths of electrical current from causing electrical
shock and fire hazards. To prevent any unintended arcs after welding, cut off
the excess wire that extends past the end of the nozzle more than ¼".
•Risk of burns: Do not touch the welded materials with bare hands, as the
welded materials are hot and can cause severe burns. Do not touch MIG gun
nozzle or tip of the electrode holder after welding until it has been cooled.
• Wear garments that are oil-free with no pockets or cuffs that will collect
sparks.
•Risk of UV and IR arc rays: Do not look at the welding arc without proper eye
protection, as the welding arc produces ultraviolet (UV) and infrared (IR) rays.
Use shields that adheres to ANSI Z87.1. For welders under 160 A output, use
a shade 10 lens; for above 160 A, use a shade 12 lens. Wear flame
retardant clothes, leather shirts, pants or shoes to cover the bare skin from
the arc.
• Use appropriate shield to prevent other personnel from being affected by
harmful rays.
SAFETY GUIDELINES
8
MIG 140 INVERTER WELDER 058-9305-6
•Risk of electromagnetic fields: Electromagnetic field can damage electrical
and electronic devices like pacemakers and hearing aids. Make sure people
using pacemakers are away from your welding area when welding. Always
wrap the MIG gun and ground cable together.
WARNING!
Potential hazard that could result in serious injury or loss of life.
•Do not allow unskilled or untrained individuals to install and operate this
welder.
•Before operating the welder, check the insulation of the ground cable, power
cord, and welding cable for damage. Replace or repair the damaged
components before using the welder. Use only recommended parts for
replacement.
• Keep hands and fingers away from moving parts such as drive roll or fan
while the welder is in use.
• Avoid contacting or touching welding wire, work piece, ground connection or
electrode from another welder.
• Do not drape cables over or around the body.
• Do not point MIG gun toward yourself or other personnel.
• Consult a doctor before using the electric arc welder.
• Always have a secure stance while welding to prevent accident.
• Do not use this welder when you are tired or under influence of alcohol or
drugs.
• Connect the ground lead close to the work area to ensure proper ground
connection.
• Always secure the high pressure cylinder upright to a cart or stationary
object.
• Do not use a welder to thaw frozen pipes.
• Do not look into the valve of the high pressure cylinder when opening it.
SAFETY GUIDELINES
9
MIG 140 INVERTER WELDER 058-9305-6
Note: Recycle the unwanted materials rather than disposing of them as waste. Sort the tools, hoses
and packaging in specific categories. Take them to the local recycling center or dispose of them in
an environmentally safe way.
CAUTION!
Potential hazard that may result in moderate injury or damage to
equipment.
• Do not operate the welder if the welding cables, electrode, MIG gun, wire or
wire feed system is wet. Do not immerse them in water. The welder and its
components must be completely dry before attempting to use the welder.
•Keep the welder in the OFF position when not in use.
•Do not wear watches, rings, bracelets, or loose clothing when using the
welder.
• Maintain a correct position while using the welder. Mount the welder on a
secure bench or cart to prevent if from tipping over or falling.
• Wear a full covered helmet with appropriate shade that conforms to
ANSI Z87.1 safety standard, proper gloves, and protective clothing such as
leather shirt, coat, pants, and insulated footwear to prevent the skin from
being exposed to hot metals, UV and IR rays while welding.
• Do not overheat or overuse the welder to prevent it from being heated. Allow
proper cooling time between duty cycles. Always use this welder in the rated
duty cycle to prevent excessive heat and failure.
• Ensure that all the components are clean and in good working condition before
use.
• Do not use an extension cord, as it causes the voltage to drop and affects
the performance of the welder. If needed, use an extension cord having a
minimum size of 12 gauge and maximum length of 25 feet.
•Use safety goggles and ear protection:
Wear safety glasses with side shields when operating the
welder and verify that others in the work area are also
wearing safety glasses. Safety glasses must conform to
American National Standards Institute (ANSI Z87.1)
requirements and must provide protection from flying
particles from the front and the sides.
Always wear ear protection to help prevent hearing damage.
Failure to comply may result in loss of hearing.
MC-OM-01
KEY PARTS DIAGRAM
10
MIG 140 INVERTER WELDER 058-9305-6
No. Description No. Description
1 Welding voltage control 9 2T/4T selector
2 Wire speed control 10 MIG/stick selector
3 Power indicator 11 MIG gun connection
4 Thermal overload indicator 12 Electrode cable connection
5 Output current indicator 13 MIG gun trigger connection
6 Spool gun/MIG Selector 14 MIG gun
7 Gas test switch 15 Ground cable with clamp
8 Power cord 16 Grounding cable connection
MC-589305-01
IGBT INVERTER WIRE FEED WELDER
SOUDEUSE DEVIDOIR INVERSEUR IGBT
4
56
7
8
9
10
V
V
POWER
ALIMENTATION
SPOOL GUN
PISTOLET À BOBINE
MIG/MIG
STICK/BAGUETTE 4-STEP
TEST GAS
058-9305
MX MIG 140 INVERTER
WIRE
V
WORK
MARCHE
ALARM
MD
4
56
7
8
9
10
MIG/MIG
2-STEP
1
2
3
4
567
8
9
11
12
13
14
15 16
10
KEY PARTS DIAGRAM
11
MIG 140 INVERTER WELDER 058-9305-6
Welder back panel
No. Description No. Description
1 Inert gas connection 2 Power switch
GAS INPUT
ENTRÊE DE GAZ
110V - 120V
1PH
OFF
ON
MARCHE
ARRÊT
POWER
PUISSANCE
2
MC-589306-03
1
IMPORTANT INFORMATION
12
MIG 140 INVERTER WELDER 058-9305-6
General use
The Mastercraft Maximum® portable MIG 140 Inverter Welder uses 120 V AC single phase,
60 Hz with a 16 A time delayed fuse or circuit breaker. This welder is ideal to weld carbon steel and
stainless steel used in hobby and light duty applications.
Guidelines for proper usage and description
Removing from carton
1. Unpack the carton, bags or Styrofoam containing the welder and accessories.
2. Check the contents with the packaging content list page 17-18.
After unpacking the welder unit, inspect for any damage that may have occurred during transit.
Check for loose, missing or damaged parts. A shipping damage claim must be filed with carrier.
Welder kit components
Electrode cable connection
This connection is located on the lower front panel and connects the cable of the electrode holder
with the welder during the stick welding mode.
Electrode holder
The holder is used for holding the electrode during stick welding.
Ground cable connection
This connection is located in the lower front panel and connects the ground cable and clamp to the
welder.
Gas hose
This hose connects the welder to the gas regulator.
Gas regulator
This regulator is installed on the shielding gas cylinder to regulate gas flow during MIG welding of
solid wires.
Gas test switch
This switch checks whether shielding gas flows through the gas shroud of the welding gun.
Ground cable with clamp
The ground cable with clamp provides grounding connection for the work piece.
IMPORTANT INFORMATION
13
MIG 140 INVERTER WELDER 058-9305-6
Inert gas connection
This connection is located in the back panel and connects the inert gas hose from the gas cylinder
to the welder providing the welder with shielding gas in the MIG welding mode.
MIG gun connection
This connection is located in the lower front panel and serves as a connection for both the wire feed
and shielding gas for the MIG gun or spool gun during the MIG welding mode.
MIG gun trigger connection
This MIG gun trigger connection (1) is located
in the lower front panel and connects the
4-pin quick connect plug of the MIG gun or the
spool gun (not included) with the welder.
Connections 1 and 2 are provided for the MIG
gun/spool gun and connections 3 and 4 are
provided for the wire feed motor.
MIG/stick selector
This selector is located on the upper front panel and used to select either MIG welding mode or stick
welding mode.
Power switch
This switch is located on the back panel to turn the welder ON or OFF. In the OFF position, there is
no power supply to the MIG gun or electrode holder circuit of the welder. In the ON position, power
is supplied to the main transformer and control circuit. Always turn the power switch OFF and unplug
the welder before performing any maintenance.
Power ON indicator
This indicator is located on the upper front panel and glows when the welder is turned ON.
Spool gun/MIG selector
This selector is located on the upper front panel. It is switched to spool gun mode when a spool gun
(not included) is being used, otherwise it should be in the MIG mode.
Thermal overload indicator
This indicator is located on the upper front panel. It glows when the welder is overloaded and the
internal temperature is too high. The welder will turn off automatically during overload condition. The
fan continues to work even if the welder shuts down. When the internal temperature is decreased,
this indicator stops glowing indicating that the welder is ready to use.
12
34
MC-589305-02
1
IGBT INVERTER WIRE FEED WELDER
SOUDEUSE DEVIDOIR INVERSEUR IGBT
IMPORTANT INFORMATION
14
MIG 140 INVERTER WELDER 058-9305-6
Welding voltage control
This setting is located on the upper front panel. It is used to adjust the welding voltage when MIG
mode is engaged.
Output current indicator
The indicator is located on the upper front panel and glows when the welder is providing sufficient
weld power.
Wire speed control
This control is located on the upper front panel and controls the speed at which the wire is fed out
of the welding torch. This control adjusts the welding amperage when the stick mode is engaged.
The wire speed needs to be closely matched to the rate at which the wire melts. The wire speed
must be selected based on the type and diameter of the wire being used, the heat setting selected
and the welding position to be used.
Note: The wire fed will be faster without an arc and slower when an arc is being drawn.
2T/4T selector
This selector is located on the upper front panel and used to select either 2T mode or 4T mode.
2T mode: This is called two-tact mode, in which the welding current flows only when the welding
torch is kept on the work piece. In this mode, simply touch the work piece with the torch and hold
the trigger to start the arc. Continue holding the trigger while welding. Release the trigger to finish
the process.
4T mode: This is called four-tact mode, which requires a sequence of operation with the welding
torch. In this mode, push and release the trigger once to start welding, and push and release once to
stop the welding.
Polarity changing
For flux core welding (no shielding gas is
required), the red MIG gun lead is connected to
negative (“-”) polarity terminal and the ground
cable is connected to the positive (“+”)
terminal.
For MIG welding (solid wire) using shielding
gas, the red MIG gun lead is connected to
positive (“+”) and the ground cable is
connected to negative (“-”). Tighten the leads
using the fasteners.
NO
GAS GAS
MC-589305-03
IMPORTANT INFORMATION
15
MIG 140 INVERTER WELDER 058-9305-6
Gas selection
Different materials require different shielding gas when MIG welding. Refer to the set up chart inside
the wire drive compartment.
Mild steel: Use 75% Argon and 25% for reduced spatter and reduced penetration for thinner
materials. Use CO2 for deeper penetration and increased spatter.
Note: Do not use argon gas concentrations higher than 75% on steel. The result will be extremely
poor penetration, porosity, and brittleness of weld.
Stainless steel: Use a mixed gas consisting of Helium, Argon, and CO2.
Aluminum or bronze: Use 100% Argon.
Electrode
The welding electrode is a rod coated with a layer of flux. During the process of welding, electrical
current flows between the electrode (rod) and the grounded metal work piece. The intense heat of
the arc between the rod and the grounded metal melts the electrode and the flux. The most popular
electrodes are mentioned below:
Torch travel
Refers to the movement of the welding torch along the weld joint.
Travel direction
Refers to the direction of the torch moving along the weld joint in relation to the weld puddle.
Travel speed
The rate at which the torch is being moved along the weld joint.
Type of
electrode Tensile strength Application
E6011 60,000 PSI Deep penetration process
E6013 60,000 PSI Poor fitup application
E7014 70,000 PSI High deposition and fast travel speed with light
penetration process
E7018 70,000 PSI Tack welding and out of position application
IMPORTANT INFORMATION
16
MIG 140 INVERTER WELDER 058-9305-6
Wire drive compartment
The wire drive compartment has wire feed components such as wire spool (1), polarity terminals (2),
drive tension adjusting knob (3), drive tension arm (4), drive roll (5), and a set up chart (6).
WARNING / AVERTISSEMENT
ELECTRIC SHOCK can kill
UN CHOC ÉLECTRIQUE peut tuer.
MOUING PARTS can cause injury.
LES PIÉCES MOBILES peuvent causer des blessures.
• Welding wire and drive parts may be at welding voltage.
• Keep away from moving parts.
• Ne vous approchez pas des pièces mobiles.
• Maintenez tous les couvercles, panneaus et portes fermés et
solidement en place.
• Keep all doors, covers and panels closed and securely in place.
• Le fil de soudure et les pièces motrices sont peut-être a la
tension de soudage.
• Ne touchez pas le fil oules parties motrices à mains nues ou
avec des outils lorsque la detente est sous, pression.
• Do not touch wire or drive parts with bare hands or tools when
trigger is depressed.
2
4
5
1
DCEN
DCEN
FLUX CORE WIRE
FIL AVEC ÂME EN FLUX
Courant continu polarité normale
Polarity switch setting:
Réglage du commutateur de polarité:
Direct current, electrode nagative
DCEP
DCEP
MIG
MIG
Direct current, electrode positive
Courant continu, electrode positive
Polarity switch setting:
Réglage du commutateur de polarité:
STICK
BAGUETTE
Polarity switch setting:
Réglage du commutateur de polarité:
+
++
-
-
-
NO GAS/PAS DE GAZ
GAS/GAZ
3
6
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