Heisenbugs In My Tempest

Programmer buddy of mine coined the term Heisnbug for programs that bomb
normally, but work fine in debug. I think my Tempest monitor has one,
because it doesn't work, except when I try to fix it, when it works fine.

(I'm mostly blowing off steam here, though if someone sees a solution in
this rant I'm happy to hear it).

Right after I first installed my Tempest MG, board came up but the
spotkiller was on the montior. Wasted some time thinging it was the MG.
Finally hooked the scope to the X/Y out test points, picutre looked perfect.
Figured it had to be the harness, when all of s sudden it started working.
Closed it up and played Tempest.

A few days ago it happens again. Monitor goes dead but it plays blind. Start
testing: Perfect picture at the test points. Perfect picture at the plug
into the monitor. Spot killer on.

OK, Greg Woodcock's FAQ at this point says turn the brightness up and check
to see if a qudrant is missing, indicating bad transistors. Turn up the
brightness, and I can sort-of see dots around the center of the scrren. I
figure I'll take the smoked glass off to see things better.

I take the glass off, power it up -- and the *!@!&^~#$!!!! picture comes up
perfect. Take a deep breath. Might as well give it a good cleaning while
it's open, put everything back together, and play a few games.

I turn the machine on tonight for a quick game before hitting the hay, and
now there's no picture again.

I suppose I'l open her up again tomorrow. Hopefully I'll have a better
direction to start in, before she just starts working on her own again --
until I close her up.

Last week it was a bootleg Rally-X boardset that couldn't make up it's mind
if it wanted to work or not. It's working now and I don't know for the life
of me what I did to make it work.

I'm going to have to go back and re-read the answer to why we do this again.
:-)

-Chris

==========================================================
Chris Candreva -- chris@westnet.com -- (914) 967-7816
WestNet Internet Services of Westchester
http://www.westnet.com/
Received on Wed Sep 29 23:23:58 1999