Ok, received the board and confirmed there's nothing wrong with the multi board at all. There was some corrosion on the b-board by the LS245 IC at 10D, which I repaired and now the B-board + multi works fine.
There's a separate issue with the a-board which leaves horizontal stripes missing from sprites in the middle field of the screen only. I can't see any obvious damage, so suspect a custom chip or something (could just be an LS chip somewhere though). If anyone has any pointers on that one, here's an image which helps show the problem.
There's a separate issue with the a-board which leaves horizontal stripes missing from sprites in the middle field of the screen only. I can't see any obvious damage, so suspect a custom chip or something (could just be an LS chip somewhere though). If anyone has any pointers on that one, here's an image which helps show the problem.
