[Ham-Computers] Question about power supply in computer

[WA5CAB at cs.com]

Brian,

I haven't any idea where the smoke smell may have come from, although I'll 
add to Duane's pet hair comment that at least in most parts of the country, even 
air conditioned houses exude dust.  And consumer and light industrial grade 
computers do not have air filters.  About once a year, I shut all of our 
machines down, drag the dust collector vacuum from my shop into the house and give 
them all a thorough cleaning.  Amazing how much I dump out after I'm finished.

However, relative to your problem, it is normal with the last several 
generations of computer power supplies for the fan to start momentarily when power is 
first externally applied.  If the fan turns momentarily and doesn't stop 
abruptly, it isn't likely to be the source of the smoky smell.  And if it turns, 
then at least the 12 volt part of the PS is working at least initially.  Sniff 
around, just as you would in a hollow state set.  If something burned, you 
should be able to smell it.

This is unrelated to your problem, but I thought I'd insert a warning about 
something not to do related to power supplies.  Most of them have a rocker 
switch on the supply itself.  Normally it is left on and the supply remotely 
controlled either from the computer front panel or by the system (board).  If your 
computer is connected to a medium power APC UPS, be sure that rocker switch is 
ON before turning on the UPS.  With everything (all AC cords and for that 
matter other signal level cords) connected and the UPS on,  turning that rocker 
switch ON wiped out two brand new 1.5 KVA APC UPS's in a row.  With two 
different power supplies, different wattages and different manufacturers.  This was 
late last year when I was fighting my unilateral re-boot problem and changing 
sytem boards and everything else in sight.  Fortunately, APC and Office Depot 
have a good (no questions asked) warranty policy.  But APC hasn't responded to 
my report of the vulnerability either.  I haven't tried it on anything other 
than the 1.5 KVA units (now I'm gun shy).  The third unit has survived 6 months 
of 24/7 operation, but the rocker switch hasn't been touched.

The predecessor to the 1.5 KVA APC's was a commercial 1.25 KVA unit that 
weighed about four times as much.  It went into service around 1992 and ran almost 
24/7/365 until late 2004.  Rocker switches didn't faze it.  Wish it were 
still available.

In a message dated 5/15/2005 10:22:02 PM Central Daylight Time, 
ka5bkg at sbcglobal.net writes: 
> >>From: Brian K. Gaskamp <ka5bkg at sbcglobal.net>
> >>To: ham-computers at mailman.qth.net
> >>Subject: [Ham-Computers] Question about power supply in computer
> >>Date: Sunday, May 15, 2005 7:22 PM
> >>
> >>I have a computer over here that wont turn on, and when I plug it in the
> >fan
> >>turns briefly and then quits.
> >>I'm guessing the power supply went out in it, but wanted some opinions.
> >>
> >>Or maybe what to look for.
> 

Robert Downs - Houston
<http://www.wa5cab.com> (Web Store)
MVPA 9480
<wa5cab at cs.com> (Primary email)
<wa5cab at houston.rr.com> (Backup email)