Intermittent power supply (OT)

From: Charles E. Fox <>
Date: Sun Dec 29 06:38:01 2002

At 06:41 PM 28/12/2002 +0000, you wrote:
> >
> > Hi, has anyone experienced a condition in a pc power supply that would
> > intermittently put out a high enough voltage to zap the hard drive?
>Is it zapping anything else?
>If not, then I guess the +5V line is probably not the cause of the
>problem, which in turn, means the PSU regulation loop is basically OK
>(these supplies regulate the 5V line and hope all the others follow :-)).
>An open-circuit in the sense circuit can make the output go sky-high, but
>then all outputs tend to go high together.
>Defective output capacitors in SMPSUs can cause high-ish voltage spikes
>on the outputs -- and generally only on one output. Perhaps the
>capacitors for the +12V rail are failing. If you have an ESR meter you
>could check them. The +12V rail is generally used by the hard drive and
>RS232 drivers only in modern machines -- the floppy drive probably only
>needs +5V. And the RS232 drives (if 'traditional') will stand serious
>overvoltage on the supply lines.

Thanks Tony and Gary, I will check that.


                 Charlie Fox
                                 Charles E. Fox Video Production
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Received on Sun Dec 29 2002 - 06:38:01 GMT

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