Lincoln Electric INVERTEC STT Series Service Manual page 48

F-7
TROUBLESHOOTING GUIDE
PROBLEMS
(SYMPTOMS)
No output. Main fuses are open,
indicating excessive current draw.
Machine loses output when gun
trigger is pulled or arc is struck.
Machine output returns after a few
seconds and trigger is pulled again.
The thermal indicator light is lit.
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)
OUTPUT PROBLEMS
1. With the input power removed,
inspect input leads for possible
shorts or grounds or miscon-
nections.
2. Install new fuses and reapply
power. If fuses open again,
contact your
Authorized
Facility.
1. The overcurrent sensor is acti-
vated, indicating that too much
output current is being drawn
from the machine.
welding current demands or
remove the "fault" in welding
cables.
2. Make sure that the gun tip is not
"shorted" to the work surface
and that the proper welding pro-
cedures are being used.
CAUTION
INVERTEC STT
detailed in the beginning of this manual.
RECOMMENDED
COURSE OF ACTION
1. Check the input power switch
(S1) and the reconnect switch
for "shorted" or "grounded"
wires or connections.
2. Perform the Input Rectifier
Test.
local Lincoln
3. Perform the Switch Board
Field Service
Test.
1. The current sensor may be
faulty.
2. The control PC board may be
Reduce
faulty.
F-7
Observe Safety Guidelines