Temple of Doom: No Motion Objects (Sprites)

FlashShift

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Have been debugging this issue for a few days, and ruled out a lot of things but haven't been able to find the source.

Symptoms:

Motion Objects test is completely blank.
Parameter Buffer test is completely blank.
Motion Object Size test is completely blank.
No motion objects / characters in game or title sequence at all.

Things I know:
1. The tiles are getting loaded into RAM and apparently moving in some buffer somewhere. If I rake certain pins on 3K or 2K, I see ghosts of the sprites moving, but not enough to root cause it.
2. I am getting strong signals from 5-8L LS283s.
3. The chip select and outputs on all EPROMs are hot. I think 233 and 234 are responsible for the sprites, not sure... but everything is signaling the way it should.
4. I have one bad SLAG (new one ordered), but moving the other three around doesn't restore MOBs.
5. All ROMs are good, dumped and compared / tested in MAME. My program ROMs (right stack) do not match anything MAME has but if I copy the rom images in, they work in MAME. Guessing a different variant of the game. All graphics and sound EPROMs match.

Things I tried:
Piggybacking 74LS74s, 74LS153s, 74LS00, 74LS86 @ 1A and a couple others.
Piggybacking 74LS245 SRAM chips (244's on order).
2K and 3K share 3J in common; I scoped it and all the inputs/outputs look like they're moving data.

Any help appreciated.
 
Last edited:
followup, 2K and 3K both buffer these sprites (every other line); replaced both and sprites showed up disjoint on screen. Final fix was to replace two bad LS163's near them at 2J,2H. After replacing all four ICs, graphics are perfect.
 
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