Lincoln Electric LN-9 SVM127-A Service Manual page 69

F-11
TROUBLESHOOTING GUIDE
PROBLEMS
(SYMPTOMS)
The SET voltage is erratic or not
adjustable over the entire range of
control. The actual voltage is also
erratic like the SET voltage.
The field fuse (F101), located on
the power PC board, repeatedly
fails.
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 for electrical troubleshooting assistance before you proceed. Call
216-383-2531 or 1-800-833-9353.
TROUBLESHOOTING & REPAIR
POSSIBLE AREAS OF
MISADJUSTMENT(S)
FUNCTION PROBLEMS
1. Check for loose or faulty con-
nections on leads #634, #635
and #636 between the voltage
control potentiometer (R3) and
the voltage PC board.
1. Very rapid and repetitive gun
triggering can possibly cause
the field fuse to fail.
CAUTION
LN-9 Wire Feeder
Observe Safety Guidelines
detailed in the beginning of this manual.
RECOMMENDED
COURSE OF ACTION
1. Remove power to the LN-9 and
disconnect Plug J1 from the
voltage PC board. Check the
resistance of the voltage control
potentiometer (R3).
measured from the wiper (lead
#635) to lead #634, the resis-
tance should vary smoothly
from 0 to 10,000 ohms when the
shaft is rotated.
2. The voltage PC board may be
faulty. Replace.
1. Perform the T1 Transformer
Test.
2. Perform the Wire Drive Motor
Test.
3. Disconnect the meter board. If
the problem is resolved, the
meter board may be faulty.
4. The power PC board may be
faulty. Replace.
F-11
When