I have a liebert GXT1500RT-230 UPS WITH PCB PSDR 1063-01460-02-942.
I changed a blown igbt G30N60A4 one month ago and the ups worked.Now the igbt is again short circuited.Same problem as before.I can't see any other problem.Can you help me?
I don't think this is the problem.I will change the photocoupler that drives the gate of igbt.It doesn't seem burnt but I can't think of something else.Any service manual of on-line ups with schematic diagram and test points would be appreciated..