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Date: Fri, 12 Sep 1997 01:12:31 -0600 (MDT)
From: Doug Russell <drussell@saturn-tech.com>
To: Pius Fischer <pius@ienet.com>
cc: freebsd-hardware@FreeBSD.ORG, terryl@ienet.com, robert@ienet.com
Subject: Re: wdunwedge failed
In-Reply-To: <199709120321.UAA25833@iago.ienet.com>
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On Thu, 11 Sep 1997, Pius Fischer wrote:

> Sorry, for the very late reply ...

Hehe.... Happens to the best of us.  :)

> On Thu, 21 Aug 1997, drussell@saturn-tech.com wrote:
> >On Thu, 21 Aug 1997, Mike Smith wrote:

> > It may not be the problem, but I would take a multimeter and check out the
> > +12 volt supply while the machine is in this failed state.  The hard drive
> > most likely uses the 12 volt for spindle motor, etc., and most VGA cards
> > use the +12 and -12 supplies for the RAMDAC.  If the 12 volt line is
> > really funky (might need a scope to see if it is fluctuating, poorly
> > filtered due to a dead filter capacitor or something, etc.), the power
> > supply is the suspect.
> >
> > Method B, of course, is to swap in a known good supply, and see if the
> > problem happens again.  :)
> >
> > You'd be surprised how many strange problems are caused by a flakey power
> > supply.  Don't ever buy one of those cheapo $30 mini-tower (or whatever)
> > case deals.  The power supply in a $30 case probably isn't too wonderful.
> > Getting better built cases is an added bonus, too.  :)
> 
> Yes, the power supply was indeed the problem! The voltmeter reading
> across the bad machine's power supply was a very unsteady 13 - 13.5
> volts (if I remember correctly). On a good machine standing next to
> it, the voltmeter gave a rock solid 12.3 volt reading. We then got a
> slightly fancier chassis with a new power supply and we haven't seen
> this wdunwedge/flickering monitor problem again.

People probably don't suspect the P/S as often as they should.  Testing it
out or swapping in another one for strange crashing problems, etc. is
often a good idea.

There is no substitute for good hardware, folks, and that includes
things like like the power supply.

Later......						<Doug>