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[OM] Re: Nathan's PAD 26/10/2008: my kingdom

Subject: [OM] Re: Nathan's PAD 26/10/2008: my kingdom
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Wed, 05 Nov 2008 13:50:52 -0500
Reminds me of a baffling case I had about 1980.  Back then I was the 
software support manager for a large scale mainframe timesharing complex 
with three CPUs occupying a 12,000 square foot machine room chock full 
of disks, printers, tapes and other equipment.  One day one of the CPUs 
just froze up and required a reboot... something you just aren't 
supposed to do with main frames and especially a time sharing complex 
with many hundreds of terminals attached.  It tends to tick off the 
users.  But damned if it didn't happen again in a day or two.  And then, 
over the next couple of weeks, it happened several more times.  Not 
every day but enough to be very disconcerting.  But it finally happened 
enough that we were able to notice that it always happened between 5:30 
and 6:00.

To make a long story short we finally figured out that the failure was 
tied to the incremental backup cycle which normally began at about 6:00. 
  The tape operator would wheel a shopping basket sized cart of magnetic 
tapes past that CPU every night as he began to prepare for the 6:00 
backup.  If he happened to come close enough to the CPU a giant static 
spark would leap from the front of the cart (out of his view) to the 
cover and frame of the afflicted CPU.  Not a good thing but normally not 
harmful if the CPU was properly grounded.  But it wasn't grounded and 
the big static spark would kill it instantly.  As it turned out the CPU 
had been serviced recently and the servicing engineer had forgotten to 
reattach the frame ground strap after removing it during the servicing.

Sometimes it takes some good luck as well as good detective work to 
ferret out the source of a problem.

Chuck Norcutt



Ken Norton wrote:
>  >At least until the cat decides to go and sit on the
>> keyboard. The laptop gets very unstable by then ;-)
> 
> 
> 
> Years ago, I worked software technical support. These were the days before
> the x386 processor and most PCs were less than stable in a high RF or static
> environment.  We provided scheduling/billing software systems to radio
> stations.
> 
> One day, I got a phone call and was told that the computer just went nuts
> and there was gibberish typed on the screen.  Another day she called and the
> printer started printing reports all on its own.  Later on, she calls back
> and the computer has more gibberish typed on the screen.  On it goes for
> three weeks.
> 
> This was, of course, a classic example of RF Interference wrecking havoc
> with the computer.  I had seen this happen dozens of times and the symptoms
> were nearly identical.  Within the industry, we just call it "RF".
> 
> We tried everything to recreate the problem, to no avail.  I had the station
> engineer do various things, had him check grounding and shielding, etc.  We
> even took the station off the air!  (He insisted that they didn't actually
> broadcast from that location, but from five miles away--which was
> technically correct, but a TV station did broadcast from a tower not 600
> feet away).
> 
> I was absolutely insistant that it was RF Interference, and the chief
> Engineer was equally insistant that it wasn't.
> 
> This went every day, at various times of day, for almost three weeks.
> 
> Then one day I get the call.  "Ken, you are absolutely correct.  It was RF.
> RF the cat!"  The radio station had this stray cat that the DJs had fed and
> it never left.  It became the station cat.  They named it "RF".
> 
> Well, it was wintertime in Michigan and the cat sought out a warm spot to
> sleep.  The perfect location was on top of the computer monitor.  It was
> actually quite hilarious as the cat would get statically charged and the
> hair would poof out like a sea urchin.  (I saw this happen with a Himalayan
> one time and that cat became the size of a rather large dog!)
> 
> The lady running the computer had a horseshoe shaped desk where her computer
> was on one side, the typewriter and telephone were on the other.  The
> telephone would ring, she'd turn around and answer it.  It would be an
> agency phoning in an order, so she'd load up the order form in the
> typewriter and work away.  A minute later, the computer behind her started
> beeping, printing or doing something else.  RF the cat would wake up,
> stretch, jump down off the monitor ONTO THE KEYBOARD and then onto the
> floor, exiting the room before she was aware of what had happened.
> 
> It is amazing how you can be 100%, yet 100% wrong.
> 
> AG
> 
> 
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