Centipede RAM errors

Level42

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Got a Centipede board that gives 3 beeps in test-mode. The lower half of the screen gives a lot of H-es, fire bullets are wrong but I can start a game and play. Sound is fine.

3 beeps indicates bad RAM 2101 at K7. Socketed and replaced it, still same problem.
Tried a 2nd 2101 still same problem.
Tried swapping the Pokey with my known good one, still same problem.

Any ideas ? Mux ?

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Last edited:
Recheck your work. You probably broke a trace while swapping RAMs. 3/4 beeps is the correct number of beeps, given that display.

Probably not a bad write signal, since that would effect 2 RAMs, and the garbage would be more random.
 
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