Lincoln Electric NA-3 Service Manual page 77

F-12
Troubleshooting Guide –
of specified components and when troubleshooting specific circuits.
PROBLEMS
(SYMPTOMS)
No control of power source output
from NA-3/NA-4. Power source
does have output.
The circuit breaker trips while the
NA-3/NA-4 is at idle (not feeding
wire).
The circuit breaker trips while
feeding wire.
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 216-383-2531 or 1-800-833-9353.
TROUBLESHOOTING AND REPAIR
See the Wiring Diagrams Section for location
POSSIBLE AREAS OF
MISADJUSTMENT(S)
FUNCTION PROBLEMS (Continued)
1. Check control cable leads for
proper connection to power
source.
2. Make sure the Lincoln Electric
power source is in the remote
control mode.
1. Remove the input power and
isolate the problem by unplug-
ging the printed circuit boards
one at a time (control, logic,
and variable voltage boards)
checking to see if the circuit
breaker trips when power is
reapplied. Replace the board
that causes the breaker to trip.
1. Check for possible excessive
loading on the drive motor.
Check for bent or dirty elec-
trode, milling guide tubes, or a
clogged nozzle.
CAUTION
NA-3 AND NA-4
Observe Safety Guidelines
detailed at the beginning of this manual.
RECOMMENDED
COURSE OF ACTION
1. Check the continuity of leads
#75, #76, and #77 in the
control cable.
2. Check the resistance and
operation of the open circuit
voltage control rheostat
(R223). See operating
schematic. Normal resistance
is 10,000 ohms.
3. Check the resistance and
operation of the control
rheostat (R2).
4. The optional start board may
be faulty (if used).
1. If the circuit breaker continues
to trip with all of the circuit
boards unplugged, the problem
is not in a printed circuit board.
Check the wiring harness for
"shorted" or grounded leads.
2. The circuit breaker may be
faulty. Check or replace.
1. Set the "Inch Speed" approxi-
mately the same as the weld
speed. While inching down,
check the motor armature cur-
rent in lead #539. This current
should not exceed 2 Amps DC.
If the armature current is high
and there is no evidence of
excessive loading on the wire
feed motor, perform the Wire
Feed Drive Motor Test.
2. The circuit breaker may be
faulty. Check or replace.
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