Changhsu P. Liu wrote:
>
> I was stupid that I had my computer on when I was connecting a SCSI CD-ROM
> to this PC. Nothing happened when I did it the first time. (I was changing
> jumper setup to see if it would work.) This time, when I was connecting the
> power and my connector barely touching the power connector in the back of
> the CD-ROM, I saw a flash and noise (like static in the night) from the
> power connector. My computer was shut down right away. I couldn't boot it
> anymore.
<snip>
> Thanks for any tips,
>
> Changhsu Liu

One thing many people do not realize is that an arc of electricity (that
bright flash you saw) represents an abnormally high amount of current
flow for the circuit involved. Electricity comprises of two functions -
voltage - a sort of pressure differential between two points and current
- the flow of electrons (or holes for those of the solid state
mentality) between those pressure points.  Resistance is a function of a
conductor that opposes the flow of current through a conductor.
Therefore, when a circuit is operational, the resistance of the circuit
keeps the current flow to a normal level.  However, when you tried to
make the connection, you started a current path that 'broke' and when
the arc occurred, the current had to come from someplace and travel
through something.  The current probably came from the power supply and
traveled through the power leads to the circuit card and through the
printed foil conductors on the card to that connector.  The wires from
the power supple to the mother board probably could handle the excessive
current.  But what becomes questionable is the printed circuit traces
that conducted that current.  Were they damaged?  Possible.  How much?
Good guess!  They are working now, so are they ok?  Not really.  The
circuits have been stressed; therefore, their life expectancy has been
shortened.  What can you do?  Not much, except to remember that if you
start to experience problems with this computer, don't be surprised if
you may have to replace the motherboard or SCSI card or both.

Just some additional info as to why one should never _HOT SWAP_ anything
on a computer.

--
Jean Bourvic :>))

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