weirds ms pacman pcb problem..

mrbill2084

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game plays fine.

here is the problem. :
on the 1st level,the dots are red. The maze looks different than normal 1st maze. Problem is the fruit acts like its traveling on a different maze. It goes though walls. you can eat it and registers it.

2nd level the dots are back to white.

its a real ms pac board with a 2bit speed up chip. I am thinking it has to be a bad eprom. Any ideas?
 
Not sure on the dot colors.
The speedup chip will occasionally cause the first game, first maze to be a different color. Its only the first game after its turned on.
Does this have an alternate maze chip on the mspac aux board? I think its U6. If so, thats why the fruit is acting weird.
If no to the above questions you have a board problem. I doubt its a bad eprom.
 
Not sure on the dot colors.
The speedup chip will occasionally cause the first game, first maze to be a different color. Its only the first game after its turned on.
Does this have an alternate maze chip on the mspac aux board? I think its U6. If so, thats why the fruit is acting weird.
If no to the above questions you have a board problem. I doubt its a bad eprom.

I did not look that close, but it looked like orignal eproms except for the 2 bit speed up.. I was going there to replace the monitor, but it had a blown fuse and bad edge connector. the monitor was not great, but it was not bad enought to need replacing.

I have to go back as the original joystick looks like its worn out the centering rubber grommet. It drops about 1/2", but still works. I need to get a replacement.
 
I know if you coin up a Ms Pac before the ghosts come out on the attract screen the first maze will be blue and red (Not sure about the dot colors off the top of my head).

- Mike
 
I know if you coin up a Ms Pac before the ghosts come out on the attract screen the first maze will be blue and red (Not sure about the dot colors off the top of my head).

- Mike


It does it randomly whether you coin up or not. Coining up may force it to happen(not sure) but it does happen without coining up too.
It has something to do with the code in the speedup chip. I believe this problem was fixed in marks 6pac kit and maybe some other multi's. I actually think the blue screen looks cool.
 
It does it randomly whether you coin up or not. Coining up may force it to happen(not sure) but it does happen without coining up too.
It has something to do with the code in the speedup chip. I believe this problem was fixed in marks 6pac kit and maybe some other multi's. I actually think the blue screen looks cool.

Not so much randomly... it's explained here. http://donhodges.com/ms_pacman_bugs.htm

When I did my freeplay chips, the original code would cause the blue maze to ALWAYS appear on the first level, I had to edit the code something like that to make it not bug out, ever.
 
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Yes but it does vary. I have seen several boards that dont do it every time. I have no explanation for it, just my observation.
 
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