Lincoln Electric POWER WAVE STT Operator's Manual page 25

POWER WAVE ® STT ® MODULE
PROBLEMS
(SYMPTOMS)
Thermal error indication on STT
(error 36).
General degradation of weld performance.
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your Local Lincoln Authorized
Field Service Facility for technical troubleshooting assistance before you proceed.
Observe all Safety Guidelines detailed throughout this manual
POSSIBLE CAUSE
BASIC MACHINE PROBLEMS
1. Improper fan operation.
® Module
2. STT ® Switch PC board thermostat.
3. Open thermostat circuit.
WELD AND ARC QUALITY PROBLEMS
1. Wire feed problem.
2. Cabling problems.
3. Loss of, or improper Shielding Gas.
4. Verify weld mode is correct for process.
5. Machine calibration.
6. STT ® Process ONLY: Excessive cable
inductance or STT
CAUTION
1. Check for proper fan operation. (Fans
typically run whenever output power is
on.) Check for material blocking intake or
exhaust louvers, or for excessive dirt
clogging cooling channels in machine.
2. After machine has cooled, reduce load,
duty cycle, or both. Check for material
blocking intake or exhaust louvers and
heat sink fins.
3. Check for broken wires, open connec-
tions or faulty thermostat in the STT
Module.
1. Check for feeding problems. Check actu-
al WFS vs. preset. Verify proper wire
drive and gear ratio has been selected.
2. Check for bad connections, excessive
loops in cable, etc.
NOTE: The presence of heat in the exter-
nal welding circuit indicates poor con-
nections or undersized cables.
3. Verify gas flow and type are correct.
4. Select the correct weld mode for the
application.
5. Verify the calibration of the power source
output current and voltage.
6. Excessive cable inductance or STT
® snubber malfunction. snubber malfunction can cause the tran-
sient voltage to exceed the safe operating
threshold on the STT
Under these conditions the STT
turns ON to protect itself.
Follow recommended cable guidelines to
minimize the inductance, and inspect the
snubber resistor circuit for damage.
E-7
TROUBLESHOOTING
RECOMMENDED
COURSE OF ACTION
® Switch PC board.
® switch
®
®