Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 62

F-10
Observe Safety Guidelines detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
The machine welds at very high
outputs, regardless of the Peak
Current control setting.
The Arc Force control has no effect
on the arc.
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. Make sure the start controls are
set correctly for the process
being used.
2. If the machine is in Remote con-
trol mode, change modes to
Local control. If the problem is
resolved, the remote control unit
may be defective.
1. The Arc Force control is active
only in the Stick mode.
2. The effect of the Arc Force con-
trol will be less noticeable at high
welding currents.
currents (less than 150 amps)
and check the Arc Force control
function.
CAUTION
SQUARE WAVE TIG 355
RECOMMENDED
COURSE OF ACTION
1. Perform the Static & Active
SCR Bridge Tests.
2. The power board may be faulty.
Replace.
3. The control board may be faulty.
Replace.
1. Check the Arc Force control
potentiometer for correct resis-
tance and proper operation.
2. Check the continuity of leads
Weld at low #441 and #445.
Diagram.
3. The control board may be faulty.
Replace.
F-10
See Wiring