BryanMcPhail.com

Professional software development, amateur BMW tinkering, old arcade stuff

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Konami Rush’N Attack arcade pcb repair

This pcb was in clean shape but sprites were corrupt.  It’s not very clear on the picture but it seemed every second column on the screen was missing, so was more likely to be in the sprite processing area than the ROMs (if it were the ROMs the missing lines would move around).

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I confirmed the 4 RAM chips on the top right of the board near the graphics chip involved sprites by temporarily shorting some data lines together and watching the corruption change.  I was reasonably sure one of these chips was the problem, but a logic probe showed no obvious errors, so I removed them one by one and replaced with RAM from a parts boards.

The second chip from the top was the problem – replacing fixed the error!

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