Space invaders 3 board stack, sprites are partially gone

ian1970sfan

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On my Taito 3 board stack space invaders, when playing the game itself plays fine and the invaders move and disappear when you hit them but the sprites/missiles and text are partially missing or corrupt, I've replaced the 4 SN74LS153N chips on the top board and the MB1424 custom chip as well, but there was no change.

What chips should I focus on?

Pics of the issue are below
IMG_0249.png
 
test your ram. Just to be sure this is happening on static images too right. I f it is then check your ram. I it passes check muxs 4 5 9 10 on board pvr 00001. finally chip 13 the 7442 controls the shifter and mux chips
 
it might not be the ram chip itself but the decoding for the ram is what I was saying which is screwing up what is in the ram. I said to test the ram because if it was coming up wrong then it means anything from ram decodeing through return by way of bi directional data buffers back to cpu was in play but limits the places where too look. everything else I said in my previous message was in case the ram did not check out during a ram test with a ram test rom inserted into a properly strapped board for it to work or a braze unit which bypasses the need for restrapping the board.
 
you are getting information into the rams at the wrong locations. running a ram test will say you have bad rams. the problem is probably in the ram chip addressing decoding. might have stuck address lines feeding the rams.
 
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