On  9 Dec 98 at 21:28, Kenneth J. Kovler wrote:

> On Wed, 9 Dec 1998, David Gillett wrote:
> >
> >   PC power supplies are supposed to shut down if there is a high
> > impedance across the 5v supply.  This could indicate an electrical
> > fault within this drive.  I can't imagine any other way it could
> > affect the system without the ribbon cable attached.
>
>  I think you mean "low impedance" here. this implies if a short were to be
> placed across the power supply +5v the supply would shut down, thus
> protecting from burning up tracks on the pc card and internals to the
> supply.

  Well, the temperature alarms that we installed last year *claim*
that they throw a high impedance across the 5v supply to shut down
the power supply.  In order to do this reliably, they insist on being
on a separate power lead -- if they used a short, the presence of
other devices on the lead wouldn't impair their effectiveness, so I
don't think it's a documentation error.

  Certainly a short *should* cause the power supply to shut down, and
that may be what's happening in his drive....

David G

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