CPS1 background graphics problem

[mikejmoffitt]

Have a friend's CPS1 board, has background problems. Both layers look like they have address truncation; within one 16x16 area the same four lines are repeated to make up the whole tile. Looks like the lowest of four lines, so it's stuck high.

Pushing around the board with my hand does nothing, I've re-seated the chips, both B and C boards, etc. The usual stuff isn't helping. Sprites are perfect.

Anyone have any clues or places to look? Is there some address latch that is known to frequently go bad?

 

[Westcb]

I had a world warriors with back ground images similar to your picture. It was a bad A board. Hope that's not the problem but these days it's about a 50%+ chance anytime someone posts cps1 problems.

 

[Pasky]

Best part about diagnosing CPS1 shit is making ribbon cables to connect the B board so you can scope and LA it while a game is on. Have fun.

 

[F4U57]

Like Westcb said, 50% chance it's the A board.

We're all going to be playing our collection, swapping out one loner A board. Until that board fucks out... Then what?

 

[aha2940]

Like Westcb said, 50% chance it's the A board.

We're all going to be playing our collection, swapping out one loner A board. Until that board fucks out... Then what?

MAME, I'm afraid. However I hope somebody comes with a proper solution before that, like a repro CPS1 A board or something, but I highly doubt it.

 

[mikejmoffitt]

MAME's emulation really isn't so accurate yet, there are still kludges to have it look correct in place. Maybe the solution is to have people work hard to port the CPS1 games to CPS2 :P

 

[Westcb]

MAME's emulation really isn't so accurate yet, there are still kludges to have it look correct in place. Maybe the solution is to have people work hard to port the CPS1 games to CPS2 :P

Yeah I remember drinking that koolaid when I got a cps2 multi, I was so hyped for the possibility that someone was going to do that. Too bad nothing materialized not even the cps1.5 games....