ESAB ESP-400C Installation, Operation And Maintenance Manual page 45

SECTION 6
Problem
Very high Output current
accompanied by either a left or
right over current (LED 6)
LED 10 - (red) Left IGBT
Unsaturated
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 (Q4)
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 (Q4)
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
ESP 400C and 600C Plasma Power Sources
Troubleshooting
Action
Replace the pair of IGBTs containing
the shorted IGBT
Lower the current setting
Replace left PWM/Drive PCB
Decrease remote current signal
Replace PCB1 P/N 38032
Secure connector
Replace freewheeling diode(s)
Secure P1
Secure P10
Replace PCB1 P/N 38032
Replace PCB2 P/N 38030
Secure connector
Replace freewheeling diode(s)
Secure P1
Secure P11
Replace PCB1 P/N 38032
Replace PCB3 P/N 38030
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