Lincoln Electric NA-3 Service Manual page 75

F-10
Troubleshooting Guide –
of specified components and when troubleshooting specific circuits.
PROBLEMS
(SYMPTOMS)
The wire feeds at full speed during
the inch mode (only).
The wire feeds at full speed in both
inch and weld modes.
The wire has limited or erratic
speed control in one or more
modes.
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. With the unit at idle, check light
2D on the logic board. If the
light is NOT lit, the logic board
may be faulty.
2. If light 2D is lit, the current
sensing reed switch (4CR) on
the NA-3 may be faulty or stuck
closed. In the NA-4, the current
sensing PC board may be
faulty.
1. If the optional start and crater
boards are NOT installed,
check the NA-3/NA-4 at idle
(not feeding wire). Observe
light 2A on the logic board. If
light 2A is lit, the control board
may be faulty.
If light 2A is not lit, the logic
board may be faulty.
2. If the optional start and crater
boards ARE installed, set the
current controls to minimum.
Check the wire feed speed in
the start and/or crater modes.
If the wire feeds at minimum,
replace the logic board. If not,
replace the control board.
1. Make sure the "CV-VV" switch
is in the "CV" mode. If the
problem is solved, the variable
voltage board may be faulty.
2. If the problem is in the start
mode only, replace the start
board (if used).
3. If the problem is in the crater
mode only, replace the crater
board (if used).
CAUTION
NA-3 AND NA-4
Observe Safety Guidelines
detailed at the beginning of this manual.
RECOMMENDED
COURSE OF ACTION
1. Check the wiring between the
logic board and the control
board. See wiring diagram.
2. Perform the Wire Feed Drive
Motor Test.
1. Perform the Wire Feed Drive
Motor Test.
1. Perform the Wire Feed Drive
Motor Test.
2. Check the wire feed speed
control (R3) for resistance and
smooth operation. Normal
resistance is 5000 ohms.
3. The logic board may be faulty.
4. The control board may be
faulty.
F-10