psu ac240as-01 dell Optiplex 7010 pc tower

[matser]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

OK, then I will give it a try without lamp.

[matser]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

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]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

worth atleast checking if it was the fet or the vdr failed.

[Agent24]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

Fizzing sound may have been tracking/arcing somewhere in the primary section.
Did you clean the flux off well after you did the work?

[matser]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

@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.

[Agent24]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

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.

[matser]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

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.

[kaldeis]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

Hi guys. Can u tell me what value is in R107 and R26 ?

[kaldeis]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

Hi guys. Can u tell me what value is in R107 and R26 ?

in attachment

[Air-Sidney]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

Hi guys. Can u tell me what value is in R107 and R26 ?

R26 - 39 Ohm
R107 470 Ohm
R105 or w14... - 0 Ohm

[metsys]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

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


seems like this caps is crap in this PSU

[Ndabu]

Re: psu ac240as-01 dell Optiplex 7010 pc tower

5 Band resistor
BLUE RED WHITE GOLD GREEN
63 Ω ?! If my eyes got the right colors

Thank you very much , God bless!