ESAB EPP-400 Manuel D'instructions page 301

section 6
6.4.2 troubleshooting freewheeling diode and iGbts
Freewheeling Diodes and IGBTs
1. Remove top cover.
2. Remove "incoming" bus bars.
3. Remove PCB2 and PCB3 from IGBTs. (PC boards are held in place by four screws each.)
caution
Emitter
caution
after pcb2 and/or pcb3 have been removed, protect
against electrostatic damage. the emitter and the
gate of each affected iGbt must be jumpered togeth-
er to prevent electrostatic damage.
Gate
electrostatic discharge hazard
electrostatic discharge may damage these components.
• Damage is accumulative and may only appear as shortened compo-
nent life and not as a catastrophic failure.
• Wear a protective ground strap when handling to prevent damage
to PCB components.
• Always place a pc board in a static-free bag when not installed.
4. Remove bus bars between capacitor banks, IGBTs and freewheeling
diodes.
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troubleshootinG