"Dave (from the UK)"
wrote in message ...
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.


Electrolytic capacitors are pennies to a couple of quid or so. That PSU must
have hundreds of them to make buying a new computer more economical!

Seriously, it'd be a real shame to junk that machine for a few bad caps. Try
heating each cap (on the metallic top bit) with the tip of a soldering iron,
taking safety precautions of course, like disconnecting from the mains
during the heating process. Get the caps hot to the touch but not so hot
they explode. After heating each cap try powering on until you get a result.
It's usually the little 'uns which cause power-up problems, like 10uF or
thereabouts.

You can use a heat gun or hairdryer to heat the caps, but the snag is that
will only tell you there are bad caps, not which ones as it heats everything
in sight!

If that doesn't work then it gets more complicated. An ESR meter would help-
that's assuming it is indeed a cap problem.

Incidentally- it could be a dead motherboard, which would be a real shame.

Dave