ESAB Precision Plasmarc EPP-450 Manuel D'instructions page 43

section 6
problem
Very high Output current ac-
companied by either a left or
right over current (LED 6)
LED 10 - (red) Left IGBT Un-
saturated
LED 11 - (red) Right IGBT
Unsaturated
possible cause
Shorted IGBT
Current pot set too high
Faulty left PWM / Drive PCB
High remote current signal
Faulty PCB1
Black wire connecting IGBT (Q2) collector to P3 of the
left PWM / Drive PCB (PCB2) is disconnected.
Shorted Freewheeling Diode(s)
Loose or unplugged P1 connector at the left PWM /
Drive PCB
Loose or unplugged P10 connector at PCB1
Faulty PCB1
Faulty left PWM / Drive PCB
Black wire connecting IGBT (Q5) collector to P3 of the
right PWM / Drive PCB (PCB3) is disconnected.
Shorted Freewheeling Diode(s)
Loose or unplugged P1 connector at the left PWM /
Drive PCB
Loose or unplugged P10 connector at PCB1
Faulty PCB1
Faulty right PWM / Drive PCB
43
troubleshootinG
action
Replace the IGBTs
Lower the current setting
Replace left PWM / Drive PCB
Decrease remote current signal
Replace PCB1 P/N 0558038312
Secure connector
Replace freewheeling diode(s)
Secure P1
Secure P10
Replace PCB1 P/N 0558038312
Replace PCB2 P/N 0558038324
Secure connector
Replace freewheeling diode(s)
Secure P1
Secure P11
Replace PCB1 P/N 0558038312
Replace PCB3 P/N 0558038324