Bad Ceramic in a Dell 390SFF PSU

[cruzinforit]

This thread is also over at JG, I just posted it and don't feel like reposting it over here. We have a lot of these SFF PSUs fail the same way, this little Ceramic blows with a snap crackle and pop. Wonder what's causing them to blow.

http://www.jonnyguru.com/forums/showthread.php?t=12806

[linuxguru]

Re: Bad Ceramic in a Dell 390SFF PSU

That's the capacitor in the primary-side RC snubber for the main MOSFET switch. It has to be low-ESR as well as have a good surge voltage spec. If not, it will likely overheat and eventually fail. If possible, it should be replaced by an X7R or X8R ceramic with decent voltage specs (at least 1 KV or higher).

[stj]

Re: Bad Ceramic in a Dell 390SFF PSU

i have talked extensivly about these shit psu's a long time ago here.

the cap is 1kv and needs to be 2 or 3kv to survive.

if it fails your in for a world of pain, the cap, the fet, the fuse, the fuseable resistor, the controller i.c. on the sub-board and a shitload of smd resistors are gonna smoke.

[cruzinforit]

Re: Bad Ceramic in a Dell 390SFF PSU

i have talked extensivly about these shit psu's a long time ago here.

the cap is 1kv and needs to be 2 or 3kv to survive.

if it fails your in for a world of pain, the cap, the fet, the fuse, the fuseable resistor, the controller i.c. on the sub-board and a shitload of smd resistors are gonna smoke.

Do we happen to know if the 80plus gold variant (H240ES) of these has the same problem?

[stj]

Re: Bad Ceramic in a Dell 390SFF PSU

no idea,
all the ones i'v seen are H240AS

[cruzinforit]

Re: Bad Ceramic in a Dell 390SFF PSU

Hmmm. I took one of the units to be trashed because of a bad motherboard, and replaced the motherboard. I had ordered a new capacitor for it. But then I realized this is an 80plus gold unit, the H240ES. I want to make sure to fix it pre-emptively if it's still a problem, since I'm using it now as my HTPC.