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TROUBLESHOOTING & REPAIR
F-4 F-4
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
FUNCTION PROBLEMS
The wire drive does not feed wire
and the drive rolls do not spin
1. Power source not on
2. Possible tripped breaker
3. Faulty gun trigger
4. Possible faulty control cable
1. Verify the power source is on
Verify power is being applied to
the wire feeder
2. Verify the circuit breaker of the
wire feeder or the power source
has not tripped
3. Check to see if the gun trigger is
working properly
4. Check for cable continuity, and
for broken or bent pins.
The wire feeds erratically, or the
motor LED lights.
1. Wrong drive rolls installed.
2. Possible problem with gun
3. Pressure arm or brake tension to
tight.
4. Examine the contact tip for wear
or proper size
1. Verify the correct drive rolls and
inner wire guides are installed in
the wire drive
2. Check for sharp bends in gun
liner
Check gun liner. The welding elec-
trode should slide easily through
the gun. Verify proper gun liner is
installed
3. Adjust brake tension. Adjust
pressure arm see
FIGURE A.6
4. Replace if necessary
5. If using wire conduit, verify that
the wire slides easily through the
conduit.
6. Perform the
WIRE DRIVE
MOTOR TEST
. Perform TACH
FEEDBACK TEST
.
The wire continues to feed when
the gun trigger is released.
1. Trigger interlock switch in wrong
position.
2. Gun trigger shorted or stuck
1. Check if the 2 step/ trigger inter-
lock switch is in the TRIGGER
INTERLOCK position.
2. Verify operation of the gun trig-
ger. Check for shorted trigger
leads.
LF-72/74 SINGLE/DUAL
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department at 1-888-935-3877 for electrical troubleshooting assistance before
you proceed.
LF-72/74
Observe Safety Guidelines detailed in the beginning of this manual.