First it works, then I put the PSU in the PC, also works. I go the BIOS, then I try to reboot and the room was dark. At the moment I'm not in the mood to disassembly it once again and take a look if the fet is shorted again.
Anyway thanks for your help stj, I think I give up now.
@stj: The fet is shorted again. I don't think the CM6800 is bad (the new one shows nearly the same values at meassuring without fet, as the old one). I have another fet in reserve, but as long as I don't know the real guilty part, it doesn't make sense to give it another try. I meassured and compared (diode mode) every part of the primary side with a good PSU and didn't find any differences. OK, there where some differences at the voltages of CM6800 but why isn't clear to me (as I mentioned, I'm not a electronic technician). Where do I find the VDR? Should look similar like the caps which I changed.
@Agent24: It seems the fizzing sound was from the fan. I did some greasing and it looks like it was gone (maybe also because of switching on without lamp), but the PSU was running maybe about 1-2 minutes, after that the fet was shorted again.
Were those blown capacitors, C6 and C10, part of the snubber network for the FET? Did you get correct values for replacement? Are there any other components in the snubber network? If any parts are open circuit in that area you would get problems.
"Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
-David VanHorn
I'm sure stj gave me the right values for C6/C10, on one of these caps I saw 300 (or 333nF) at 1KV, stj recommended one 680nF at 2KV for these 2 caps, which I did on every PSU I have left. Hopefully the broken C6/C10 caps are the reason for the PSU failing (I saw also broken C6/C10 caps, but the PSU was still working!).
Sorry, I'm not sure how to isolate or find the "snubber network"? But I didn't find any great different values by measuring (via diode mode) and comparing the values of the components of the primary side with a good PSU.
Today got the same PSU with exploded M5 tny280pn which may be caused by broken C6 and C10.
On one the piece was marking 331K 1KV
Waiting for parts to replace
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