PSU shuts down immediately upon power up

[badcapsal]

Hi there
Can't see this one but apologise if it's already there.
Had several PSUs now which just shut down upon switch on.
The fan does a little twitch and that's all, no output volts.
With previous PSUs I've tried replacing all caps but with no success.
Might I ask for some guidance please.
I presently have 2 OCZ StealthXstreams with this same issue.
Many thanks
Sal

[tom66]

Re: PSU shuts down immediately upon power up

Output diodes shorted -OR-

Too little/much load -OR-

Problem with startup cap

[badcapsal]

Re: PSU shuts down immediately upon power up

Hi there
Replaced the 2 caps labelled in the picture, not sure which one is the "start-up" A or B.
Removed both and checked with ESR meter.
Cap A was Teapo 10uf showing 8.6uf / 2.00 ohms.
Cap B was Teapo 100uf showing 98.2uf / 0.11 ohms.
I assume that Cap A was a problem but replaced both.
For Cap A I used a Chemi-Con KMY 22uf. I used 22uf as this is the usual value for that location on the OCZs I seen so far, will this likely be a problem with a higher value?
The PSU is up and running and powering a Pentium D840, 2GB, X1950 with no immediate problems.
Thanks for the help,
Sal

[selldoor]

Re: PSU shuts down immediately upon power up

The green cap in the black sleeve is probably a Teapo - what does that measure at.

[badcapsal]

Re: PSU shuts down immediately upon power up

Hi selldoor
PSU back in PC and working at moment, however all voltages do measure pretty good.