[REPAIRED] Chelnov graphic repair help

[Tailsnic Retroworks]

Hi, I have just received a Chelnov jamma board, and after a few time powered on, I have this issue.

As you can see in the photos, I have a sync problem on a specific zone of the screen, and also graphic glitches in sprites. I don't know where to look, if anybody has a clue.

 

[Tailsnic Retroworks]

REPAIRED!!!!

A defective Fujitsu 74LS32 on lower board, near CC32 capacitor. Tracing lines I have seen very strange input signal to a 74LS157 near CC11 capacitor, in charge of the final sync signal.

Pin 4 of 74LS157 was the output, and pins 2-3 the inputs. Pin 2 was very very very strange, and this 74LS32 was the culprit.

Replaced.

And fully alive again!!!!