Food Fight, Defender, Q*bert problems

Today during my first game party in a while, three games really acted
up.

#1) Food Fight
Symptoms: For several months the video has been jittery. Sometimes it
would work fine, and sometimes after it heated up a bit it would get
jittery. Sometimes it didn't need to heat up and would be jittery while
cold. Today, just as I was powering up for a game party, it's jittery
right off the bat.

Things tried so far:
-Switched monitors (to a known good monitor). Same problem.
-Resocketed all socketed chips on board. Same problem.
-Tried another known good board. Same problem.
-Tried both boards with both monitors. Same problem.
-Checked voltages out of audio/reg board. All right on.
-Tired jiggling connectors by hand with someone watching video. No
changes noted.

#2) Defender
First time displaying this problem. This did not happen when I left all
the games on at the same time for 8 hours for a smoke test.
After just about a half hour, game intermittenly reset going through the
rug pattern. Easy to blame on heat, but the smoke test I actually had
two more games on than today, and it was warmer then too. Today was a
cooler day (without heat on in the house besides). When it rebooted, it
didn't display any errors, and did recognize the CMOS. I have not
upgraded the RAM on the CPU. No trouble shooting attempted so far.

#3) Q*bert
Again, first time displaying this problem and did not happen during the
smoke test. A little tricky to explain. Started to happen after a
couple of hours. It didn't reset, but just intermittenly went to game
over mode. You could hit the start button and play again, but this
probably happened every third game or so. Also, as I was playing, I
could see Q*bert kind of flickering changing to other shapes/colors
(like the snake). Didn't happen all the time, but if I recall it seemed
to be a prelude to a jump to game over problem. No trouble shooting
attempted so far. The Zener diode controlling the sound board has been
upgraded (or is it downgraded) to a 24v as recommended by Roy
Chumblespuzz. The power supply is an MA303 (GV103). The main and sound
boards are GV103A.

Any ideas anyone? Any help much appreciated as I'm got another even
bigger party coming this Wednesday. Thanks,

Joe
joemagiera@ameritech.net
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Received on Sun Mar 10 14:11:25 2002