Pacman graphics collision issue

Cmndr Brain

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You'd think if you fixed enough of these, it would get easier. Then something comes along and knocks you back to reality. This pacman is having an issue when there is a collision w/ pacman and either the red or the blue ghost only. Everything plays perfect. But, when the red or the blue ghost collide w/ pacman, the sprites seem to blend their colors. I have spare pac boards to check all the socketed chips. All the memory chips are socketed and are good (the only memory chips not socketed are 2L and 2K, but those are sound rams I believe). V-ram address card is good, z-80 sync bus is good. All eproms are good. All custom chips are good. Sorry about the poor picture quality. They were taken from my bench testing screen.
pic #1 - pacman approaching blue ghost.
pic #2 - pacman and blue ghost collide. (you can see on the left is pac yellow and on right is blue ghost. In middle is orange.)
pic #3 - full collision and now 2 orange ghosts.

"que riptor"
 

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Ok, my initial assessment of it only being a collision w/ pacman was wrong. After further checking, I didn't notice it before, it seems as though other collisions/overlaps have the same issue. Here are some better pics.
 

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Im with you Brian, no matter how many of these you repair you still come across stuff you have never seen before. I have seen two orange ghosts before but if I recall it was all the time and the problem was a bad 2125 ram. I doubt this is your problem.
Yes, 2L and 2K are sound ram. How about the 3F and 3H rams? I think your problem may be in this area of the board. Do a really good check for broke or shorted traces in the bottom right corner of the board from the character roms down. Someone like Mark Spaeth who knows what handles the collision detection could tell you exactly where to look.
Concentrate on rows 1-4 columns A-H. Im pretty confident this is the area of the board the problem will be found.
One question, does the pacman die or does it go right through the ghosts?
 
Game "plays" perfect. Pacman dies and everything. I have been checking the chips that are connected to the custom color prom on the schematic. I'll work my way to the character eproms. So far, nothing seems defective. So, the search continues.
 
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