Wiring Harnesses (was: RL02 Question)

[Adrian Graham]

Years ago I was troubleshooting an old SuperMicro beast that was running a
newspaper printing press. It kept shutting down randomly but if I hit the
power button it would come up. Then randomly go down again minutes or an
hour later.

I spent many hours testing and swapping modules in and out of this thing
from a working machine and at one point it would only power up if the front
box that contained the power switch module and CDROM/floppy were out of the
enclosure and separate on the bench (but still connected to the motherboard
by an data/power cables). If I got a long screwdriver and earthed this
front box to the main enclosure the machine would go down immediately.

Power switch itself tested fine with a meter but I found there was a hidden
reset swtich that wasn't in use so I desoldered and swapped them over. All
problems went away and the customer practically carried me at shoulder
height around the press hall.

-- 
adrian/witchy
Owner of Binary Dinosaurs, the UK's biggest home computer collection?
t: @binarydinosaurs    f: facebook.com/binarydinosaurs
w: www.binarydinosaurs.co.uk

---------- Forwarded message ----------
From: allison via cctalk <cctalk at classiccmp.org>
Date: 27 March 2018 at 13:32
Subject: Re: RL02 Question
To: Aaron Jackson <aaron at aaronsplace.co.uk>, "General Discussion: On-Topic
and Off-Topic Posts" <cctalk at classiccmp.org>


> Long short story.  I got my RL02 directly through DEC while I was a
> engineer there.It was a pile of parts in the back lab.  The story was it
was pulled
> from a customersite as FS could not make it work at install.  Seems
despite being new
> just about everything that could be swapped apparently was and no one
could get it
> to spin up.   So I made a deal if I get it working its mine (ok, to be
part of
> the 11/23 in my office, which later would become mine).   After
assembling it and
> testing it sure enough it didn't spin and would turn slowly for a few
moments and quit.
> Drag out the meter and start testing voltages.  I found the motor starting
> cap (known new) had odd voltages.   A bit of ohming out later it was the
crimped
> faston connector at the end of the power line going to the capacitor.
What
> was wrong was crimped but the wire was never stripped so there was no
connection.
> The only thing never swapped was the power wiring harness.  The pile of
swapped
> boards and even heads was impressive.  I got the drive and word got around
> that it was me that solved the riddle.  I troubleshot the problem, and
> didn't swap it to death.