Lincoln Electric 11519 Service Manual page 52

F-6
Observe Safety Guidelines detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
The output voltage and wire feed is
present continuously or pulsing
when gun trigger is NOT activated.
The output voltage is present con-
tinuously when gun trigger is NOT
activated.
"TOO HOT" on the display.
Machine is dead - no open circuit
voltage output and no wire weed
when gun trigger is pulled.
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely,
contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed.
Call 1-888-935-3877.
TROUBLESHOOTING AND REPAIR
POSSIBLE AREAS OF
MISADJUSTMENT(S)
OUTPUT PROBLEMS
1. Remove the gun. If the problem
is resolved the gun trigger circuit
is faulty. Repair or replace.
2. If problem persists when gun
assembly is removed from
machine, then the problem is
within the POWER MIG 255XT.
Contact your local Lincoln Electric
Authorized Field Service Facility.
1. The thermostats may be open
due to machine overheating. If
machine operates normally
after a cooling off period then
check for proper fan operation
and ventilation. Make certain
that the machine's duty cycle
is not being exceeded.
2. Check the trigger circuit.
Leads #324 to #325 should
have continuity (zero ohms)
when the gun trigger is pulled.
If not then the gun may be
faulty - replace.
CAUTION
Power MIG® 255XT
RECOMMENDED
COURSE OF ACTION
1. Check the machine's internal
trigger leads for grounds or
shorts. See Wiring Diagram.
2. The control board may be
faulty. Replace.
1. Perform the SCR Rectifier
Assembly Tests.
2. The control board may be
faulty. Replace.
1. Check the thermostats and
associated leads for loose or
broken connections.
Wiring Diagram.
2. Unplug trigger leads and
remove gun from
machine. If problem goes
away, possible bad gun
(trigger leads shorted to
electrode)
F-6
See
the