Microwave Inverter PCB (F6645BA01GP) - Shorted Bridge Rectifier

[Cirkit]

Hello all,

I am attempting to repair a F6645BA01GP microwave inverter PCB (photos attached). The shorted bridge rectifier tripped the circuit breaker.

Before anyone mentions it, I did check that all the high voltage capacitors were discharged before testing the components on the PCB.

The IGBT doesn't seem to be shorted.

What is likely to have caused the bridge rectifier to short out?

 

[kellys_eye]

What is likely to have caused the bridge rectifier to short out?

Discounting a random failure (always possible though) then failure of the switching controller may have caused a short long enough to destroy the bridge yet see the IGBT survive. This is based on your test stating that the IGBT is ok.....

 

[Cirkit]

This is based on your test stating that the IGBT is ok.....

I removed the bridge rectifier and IGBT from the PCB and tested again. The IGBT is also shorted out!

What is likely to have caused this?

 

[kellys_eye]

Apart from potential self-failure the usual cause is the driver IC going dud which sometimes drives the device into permanent conduction and then failure. As I stated previously.....