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Re: Re: A Technology Trivia puzzler.

Subject: Re: Re: A Technology Trivia puzzler.
From: Walter Knapp <>
Date: Wed, 10 Jul 2002 10:27:25 -0400
Monty Brigham wrote:
> 
> I had s similar experience. Lightening passed through my area and fried
> my computer. I took my computer to my friendly service provider who
> quickly found one damaged resistor. He replaced the part and things
> worked fine thereafter. One piece of advise was turnoff your computer
> when a storm approaches. There is no protection from a direct hit.

That's exactly the approach I'll be using with the motherboards. I
already know where I'll be sending them. There's no component level
repairers around here. Last time this happened, it was one motherboard,
and it had scorch tracks and lots of fried components and was repaired
successfully. That was several years ago, and was the incident that
resulted in my current level of protection.

Note that two out of the three computers damaged were turned off. It
makes little difference unless you are always around and also disconnect
everything. At least in my experience.

And as my insurance agent says, you can only stop some of it. Around
here storms approach often enough that turning off for all is not really
a viable option. Though major things that are actually at the house I do.

> -----Original Message-----
> From: oryoki2000 
> Sent: Wednesday, July 10, 2002 2:52 AM
> To: 
> Subject: [Nature Recordists] Re: A Technology Trivia puzzler.
> 
> My guess:
> 
> Lightning strike to telephone pole
> sends voltage spike via phone lines,
> frying phone section of surge protectors
> with a snapping sound.  Surge protectors
> shunt high voltage to ground. Your Mac
> had a second path to ground via the
> external SCSI HD.  A ground loop is
> created, sending extra voltage along
> the SCSI bus and damaging the internal
> SCSI card.  Voltage differential in
> multiple paths to ground confirmed
> later with VOM.

The snapping sound was at the back of my G4, not the surge supressor.

And the lightning strike was more than a half mile away, nothing at all nearby.

The external HD is the key link, but it's ground and the surge
supressor's ground were the same. There is a well done common ground in
the entire house.

Walt



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