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B-1
OPERATION
LN-742 & LN-742H
B-1
OPERATING INSTRUCTIONS
Read and understand the entire Operation Section
prior to operating the machine.
SAFETY PRECAUTIONS
ELECTRIC SHOCK
can kill.
• Do not touch electrically live parts
or electrode with skin or wet
clothing.
• Insulate yourself from work or
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 containers that
have held combustibles.
ARC RAYS
can burn.
• Wear eye, ear, and body
protection.
Observe additional Safety Guidelines detailed in
the beginning of this manual.
GENERAL DESCRIPTION
The K617 LN-742 semiautomatic constant speed wire
feeder is specifically equipped for gas metal arc
welding using flux-cored Outershield electrodes and
solid wire. The LN-742 is also suitable for self-shielded
flux-cored Innershield electrodes, submerged arc
welding (if constant voltage is satisfactory), and other
open arc welding. It has been factory assembled with
the following features:
• Wire feed control [50 to 770 in./min (1.25 to 19.5
m/min) for the LN-742; 80 to 1200 in./min (2.00 to
30.5 m/min) for the LN-742H].
• Factory installed gas solenoid valve and gas
fittings.
• Wire drive uses a permanent magnet motor and
includes tool-less “quick-release” idle roll pressure
arm, outgoing guide tube and gun cable fastening.
• Optional factory installed water solenoid and fittings
for use with water cooled welding guns.
The LN-742 4-Roll is designed to provide the additional
feeding force required when using gun cables over 15
ft (4.6 m) long or when the wire is pulled long distances
(such as when bulk packages are used). Because the
four-roll feeder has twice the contact surface, it can
also help when feeding softer wires by delivering the
same or more feeding force as the two-roll with less
overall wire deformation.
RECOMMENDED PROCESSES AND
EQUIPMENT
The LN-742 is recommended for use in MIG and
Innershield welding applications with constant voltage
power sources with 42 VAC auxiliary power and a 14-
pin connector receptacle, such as the Invertec V300-
PRO, V350-PRO, DC-400, DC-600, DC-655 DC-650-
PRO, or Lincoln CV type power sources.
The LN-742 is capable of the following wire feed
ranges:
• 0.025 to 1/16 in. (0.6 to 1.6 mm) solid wire for gas-
metal-arc or CV submerged arc processes.
• 0.045 to 3/32 in. (1.2 to 2.4 mm) cored wire for
Outershield gas-metal-arc processes.
WARNING