Saturday, January 02, 2016

Konami Teenage Mutant Ninja Turtles PCB Fix

I recently extracted all my PCBs from my parent's garage. These had been sat in cold conditions since the 1990s and not used in years.

Surprisingly, everything I tested worked. Apart from my Konami TMNT which had corruption to the graphics. The sprites rendered fine in isolation, but the tiled graphics clearly had major problems.

The game ran fine.
The sound plays.
The RAM/ROM check passed.
The Mask ROM check failed. This required setting a DIP switch to test.

Unfortunately, the Mask ROM test screen was so garbled it was unreadable and I inferred the wrong Mask ROM was bad! In the end, I swapped out two ROMs rather than one. For reference the screen looks like this (not my picture!)

After desoldering the Mask ROMs, I used 27c400 EPROMs as replacements.

And everything now works. Turtle Power!

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