Professional software development, amateur BMW tinkering, old arcade game stuff


Konami TMNT arcade pcb repair #2

When I saw the check screen was literally cut down the middle with garbage, I suspected an addressing problem.





First up I checked the connections between the 052109 tilemap custom and the 2 6264 RAM chips.  Everything was good there.  Next up I checked the addressing from the CPU to the custom – this goes through 2 LS245 latches @ E24 and F24.  A logic probe showed A6 was totally dead – it had no continuity back to the CPU.  A kynar wire patch was added under the board and everything was perfect again.  I couldn’t actually find any scratched traces, so may have been a corroded thru-hole underneath a chip.




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