SuperGrafx corrupted video - PCE works fine

[vougbour]

Hello all,

A friend sent me a supergrafx to take a look at.  Console play PCE games fine, however SuperGrafx games play ok but have corrupted graphics.

My understanding is that the supergrafx has two sets of PCE engine chips, and a custom chip that combines them for supergrafx games.

I would like to tackle this problem logically, by creating a list of troubleshooting tasks to do.  If anyone can help out with identifying what i should do that would be greatly appreciated.

1. First id like to inspect the motherboard, and ensure there are no broken traces.
2. maybe replace all electro capacitors, believe there are around 20.
3. identify what PCE chips are exclusive for the supergrafx?  perhaps someone can help me with this?  as im not sure.
4. maybe look at the vram as being the issue?
5. anything else anyone can recommend?

Thanks,

Mal

[dshadoff]

For one thing, the SuperGrafx has an extra video processor and memory.

If the SuperGrafx games play OK but with corrupted graphics, I would suspect that the video chip itself is working, but somehow the memory is the problem (second choice is the video processor).  Maybe check the traces to and from the video memory chips...