SECTION 5
TROUBLESHOOTING
17
PROBLEM
POSSIBLE CAUSE
CIRCUIT CHECKS
Unit inoperative - fan
does not run
Incorrect primary condition or blown line
fuse
Incorrect linkages on voltage changeover
board
Defective Line Switch (LS)
Check incoming power to unit
Check links on voltage changeover
terminal board
Perform continuity check on Line Switch
Blows input line fuses
Defective Input Bridge (IBR)
Incorrect linkages on voltage changeover
board
Defective PB1/PB2
See IBR Troubleshooting
Check links on voltage changeover
terminal board
See PB1/PB2 Troubleshooting
No open circuit voltage 115 V ac circuit breaker tripped
MIG mode operation
1. Stick pendant/control plugged into J2
2. No contactor signal from wire
feeder/control
STICK mode operation
1. No contactor signal from
pendant/control
Check circuit breaker and reset if tripped
Check J2 and disconnect pendant/foot
control
Check MIG contactor signal - see ICB
troubleshooting
Check STICK contactor signal - see ICB
troubleshooting
No open circuit voltage Defective SCR1/R1
Missing bias voltage to Inverter Control
Board (ICB)
False thermal indication to ICB
Defective ICB
See SCR1 troubleshooting
See ICB troubleshooting
See ICB troubleshooting
Replace ICB
Excessive open circuit
voltage
Defective resistor/capacitor across Output
Bridge (OBR)
Check components R4, C7, R5, C8
Thermal overload
Exceeding duty cycle rating
Exceeding max. rated ambient temperature
See duty cycle rating chart
40 °C (104 °F)
Flashing fault indicator Input voltage not 15% and -10% of
rated requirements
Excessive line impedance
Defective Inverter Control Board (ICB)
Check incoming voltage to unit - all three
phases
Check voltage TB-1 (+) to TB-4(-). See
IBR troubleshooting
Replace ICB
Table 5-1. Troubleshooting Guide (Sheet 1 of 2)