okunewck@gondor.UUCP (Philip E. OKunewick) (03/11/86)
THe first service call I ever made took me about 5 hours to pin down.
The customer had been having problems with intermittent lockups and
unplanned reboots.
Well, I got to the site, he started running, and sure enough we got
lockups. (If you've ever tried to pin down an intermittent problem,
this sort of thing is VERY welcome to see.) The lockups were
accompanied by a spark sound, which seemed to be coming from the
terminal...
...A few hours later...
The spark had been coming from the printer tray, which was sitting
right next to the terminal. As the paper fed up, it carried a static
charge which slowly built up on the tray. (Almost exactly the same
as a Van de Graf generator.) The charge eventually reached the
potential to arc across to a ground screw. Now, a spark will
generate all sorts of noise all the way across the rf spectrum. The
computer was picking up the rf noise, which caused it to reboot.
I grounded the paper tray and told the customer to start using static
spray. This also took care of his disk errors - when you touched a
disk and got a spark...
---Duck