Dave (from the UK) wrote:
I have a HP UNIX workstation which has sat in a garage for a couple of
years. I've bought it out of storage, powered it up and it worked for
about 30 hours or so. Now it has died. I have reason to believe the
switch-mode power supply might not be fully functional, although it is
hard to tell, as it requires a signal from the motherboard to power it
up. (The PSU is not completely dead and is providing power to the
motherboard. But it is not energizing the high current lines).



One possibility is a dud cap that has dried out. Replacing all the
electrolytic in the power supply will be a bit expensive, on the
off-chance it is one of them. I might as well spend a bit more and buy a
new computer.

Has anyone got any tips on how one might find a doggy cap? Freezer
spray? Heat? Tapping them?

Debugging SMPSs is hard enough with a circuit, but I have no circuit and
no idea what lead is supposed to bring this thing into action.


Short of having a cap checking ESR meter, there is a little you can do.
YOu can take the PS apart and check all the solder joints. A bad solder
joint on the PC board can cause a problem. Look at the top of the caps.
If any are "domed" looking or look split open at a seam, they could be
leaking and bad. Also look at the caps bases for any white leakage gunk.
Any suspicious cap should be replaced.

Check the mother board caps the same way. Re seat the cpu and ram in
there sockets. Make sure the fans are not seized.

Bob


----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----