[sdiy] scsi shock

[Dave Krooshof]

Hi list,

I email the list as we had some nice discussions on grounding and shocks.
Here's another story to share, and questions to ask...

I'm typing with a sore hand, as I just got shocked by my
image scanner (apple color onescanner) while patching it.
The SCSI chain is: Mac G3 -> CD Toaster -> Scanner.
All worked fine this very evening. Nothing got moved a lot.

I just patched the cd toaster back into the chain,
with both the computer and the scanner switched on. (yes.)
I was holding the 'outgoing' SCSI cable from the toaster
and touched the connector on the scanner with that same hand.
	> Bzzzap! <
Took a voltmeter, found 126 volts AC.
The wall socket is 239 volts at the moment (good weather today).
It's a zero/phase/ground wall socket. All equipment shares 1 socket.
The scanner doesn't seem to have any short circuits, as far
as I can see now.

questions are:
- Why didn't my computer crash, or smoked the SCSI controller
or simply die?
- Why didn't the safety ground switch flip? (It does work normally)
- If a short circuit is there, why isn't it 5, 12 dc, or 230 volts AC?
(can't test the voltage on the lamp, as it can't be switched on while
not connected to the mac. No trace of 126 volts anywhere inside).

Any hints on finding the error are welcome.

I'll give my hand a rest, now.

Thanks,

Dave
-- 
____________________________________________________
And I will make thy windows of agates, and thy gates of carbuncles,
and all thy borders of pleasant stones. (Isaiah 54:12)

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http://www.xs4all.nl/~krooshof