Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 60

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Observe Safety Guidelines detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
Digital display does not light.
Machine turns on and operates nor-
mally.
The display lights but a current can-
not be preset.
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)
FUNCTION PROBLEMS
1. Contact your local authorized
Lincoln Electric Field Service
Facility.
1. Contact your local authorized
Lincoln Electric Field Service
Facility.
CAUTION
SQUARE WAVE TIG 355
RECOMMENDED
COURSE OF ACTION
1. Check for 5VDC from 2J7+ to
4J7- on the display board. If the
voltage is present and the dis-
play does NOT light, the display
board may be faulty. Replace.
2. The control board may be faulty.
Replace.
1. Set the Peak Current control
(R10) to the 12 o'clock position.
Position the Start Current switch
(S13) to the off position. The
machine should weld at approx-
imately 80 amps. If the machine
welds properly but does NOT
display the actual welding cur-
rent, the meter board may be
defective. Replace.
1a. The control board may be
defective. Replace.
2. If the machine does NOT weld
properly, check or replace the
Peak Current control poten-
tiometer (R10).
2a. The control board may be
faulty. Replace.
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