Asteroids Deluxe High Score Repair

Altan

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My Asteroids Deluxe wasn't storing high scores very well. When I brought it back to life, it occationally seemed to store a high score but then it also seemed to wipe them out. Even when it appeared to work, it never stored more than 1 high score.

I looked at the schematic and saw that C49 and C50, which are 1uf 50V radial caps, plays an important part in the high score process. I ordered 2 of these from Bob. They arrived yesterday...

I just replaced these two caps, played a few games, got a high score, powered off the game.... powered it back on and the score was saved!

I'm hopeful the problem is fixed. I'll need to give it a little more time to ensure the scores don't go away.

Hope this is helpful to someone...

... Altan
 
Turns out it's not as good as I wanted.

After playing some more and a few power cycles, the game would display strange high scores, immediately remove them, and then just show one "real" high score.

I verified the voltage at the 7055, which read -28.5V. That's fine.

I then pulled the 7055 to check if the connectors looked good. They did...

After putting the chip back in, it's behaving worse. All the scores show as "F1F1F1F1" then disappear. Each power cycle this changes a little, perhaps "FAFAFAFA" or "FBFBFBFB".

I'm thinking I need a new 7055. Just wish I had ordered it with the caps I got...

... Altan
 
Hopefully this is the final update...

I replaced the 2055/7055 but that didn't help.

I then replaced the 74175 chip and that fixed my problem. It also showed me the problem was reading back from the EAROM, not writing. I believe this because after I replaced the 74175, at first boot the high scores from the previous night appeared.

It's kind of interesting, so I'll share a little more...

1) Last night I turned on Asteroids Deluxe, it showed the bogus high scores briefly and then discarded them. High scores like 50505050 or FFFFFFF.
2) The game was played last night and several high scores were entered.
3) Game was turned off overnight. This morning I went out to Fry's and found a 74175 chip.
4) I turned on the game and it showed bogus high scores.
5) I turned off the game, pulled the main PCB and swapped the 74175
6) I booted the "repaired" board, and it showed the top 3 high scores from #2 above

So what's interesting is the power cycle I did this morning (#4) didn't write anything to the EAROM to clear the high scores from the night before. I speculate this is because the game knows what it read from EAROM was bogus (why it displays them and then seems to forget about them). Since I didn't play a game this morning, meaning I didn't create a new high score, it didn't write anything back to EAROM. So when the board was repaired, the "good" data was there. Just a theory.
 
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