Somewhere on the interweb "kony" typed:
> On Sat, 6 Oct 2007 22:07:11 +1300, "~misfit~"
> <misfit61nz@yahooligans.co.nz> wrote:
>
> > Somewhere on the interweb "kony" typed:
> > <snip>
> > > I suspect you have failed capacitor(s) in your power supply.
> >
> > I had that last week on one of my older machines. Scared the
> > bejesus out of me:
> >
> > http://test.internet-webmaster.de/upload/1191392010.jpg
>
> Unless the fan fails, I seldom see those high-side caps
> fail, it's almost always the ones after the transformer
> output is rectified in the LC circuits, either the 3.3/5/12V
> rails or the 5VSB.

I knew those were the caps you were talking about, just wanted to share my
explosive experience. So you've never seen those big ones fail? Maybe it's
something to do with the fact that we have 220V mains in NZ? You're in the
US are you not? 110V mains. /Most/ supplies I've seen are switchable so,
when used with half the cap's rated voltage are probably less likely to
fail. The fan was/is working fine.

> > That's what it looked like after I plugged the PC in (with the side
> > off and my ear right next to the PSU). Went off like a shotgun.
> > Luckilly I still had my hand on the power cord, I unplugged it in
> > about 0.002 sec. I found an Enermax supply that had died a quieter
> > death a while back that had a pair of Rubycon caps in it the same
> > size and specs as this and the one next to it. I replaced them both
> > and the PSU is running fine again.
> >
> > [Warning: There can be dangerous voltages present acroos the bigger
> > caps like these even if your PSU has been turned off for a while.
> > (mine sparked against the soldering iron) I don't recommend that
> > you open PSUs yourself unless you know what you're doing]
> >
> > I know that's not exactly what you mean by failed capacitors Kony
> > but I had to share. :-)
>
> Normally the PSU 5VSB and some parallel resistors drain
> those caps down to a negligable level. I'm wondering if you
> either had (have) another fault still, or if the remaining
> voltage on the caps was low enough to be safe, even if a bit
> startling.

I hope the latter. It was only a small spark. However, I've heard others
issue warnings about dangerous voltages being retained in PSU caps so
thought I'd mention it.

> Certainly if a high voltage cap fails it has to be replaced,
> but the more common failures are the caps around the
> existing wiring harness connection to the PCB, or (still in
> the same general vicinity on the PCB) one set of inductors
> before that point.

Yeah, I've heard that. Strangely, I've never had it happen myself. <touches
wood>

Cheers,
--
Shaun.