Ms. Pac help

GoneMad

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My friend has a MP pcb he wants me to look at. The ghosts have some color issues. The issue is exactly as described in the 13th photo from the bottom on the left here,
http://www.arcadegameover.com/pactrouble.html
What is confusing to me here is the way this is worded, or what to try to fix it.
M(red, red, cyan, cyan)

Ms Pacman's blue center in ribbon is gone.
Monsters have cyan eyes with yellow pupils.

2C bad, removed, shorted p15 to p16, or p7 is high.

Signal from 3A p9 to 2C p15 high.

Signal from 2C p7 to 3D p6 high.

3A p9 short to p16.

If the signal from 2C P7 is high, do you short p15 to p16? or
If the signal from 3A p9 is high, do you short p9 to p16?

I find the way this is worded quite confusing. Can someone help me out here? Thanks

Doug
 
2C is a 2125 ram. If the troubleshooting page is referencing that ram, then your first step is to replace it.

These are almost always soldered in, so you'll need to order a replacement chip from someone like Riptor. Might as well get a socket for it while your'e at it and socket the thing.

Before you start the work you can try piggybacking the chip on top of the suspect one to see if the issue clears up first. If it fixes your problem, then go ahead and replace the chip.
 
2C is a 2125 ram. If the troubleshooting page is referencing that ram, then your first step is to replace it.

These are almost always soldered in, so you'll need to order a replacement chip from someone like Riptor. Might as well get a socket for it while your'e at it and socket the thing.

Before you start the work you can try piggybacking the chip on top of the suspect one to see if the issue clears up first. If it fixes your problem, then go ahead and replace the chip.

OK, thanks. i don't have any of that particular ram on hand. Would it cross ref to a replacement?
 
93415, 93425. 2125 are very common. If you have some old boards laying around you might be able to find some that are socketed. It is very rare to see them socketed on a pac board unless someone has installed them. You may want to check the color proms while your at it. They are located at 4A and 7F.
If you change out the 2125 dont worry yourself about the heatsinks. They really are not absolutely needed on these.
I have a good deal on 2125 pulls. https://www.twistywristarcade.com/search?orderby=position&orderway=desc&search_query=2125
These 93425 will also work. http://www.twistywristarcade.com/ram/497-93425-ram.html
 
93415, 93425. 2125 are very common. If you have some old boards laying around you might be able to find some that are socketed. It is very rare to see them socketed on a pac board unless someone has installed them. You may want to check the color proms while your at it. They are located at 4A and 7F.
If you change out the 2125 dont worry yourself about the heatsinks. They really are not absolutely needed on these.
I have a good deal on 2125 pulls. https://www.twistywristarcade.com/search?orderby=position&orderway=desc&search_query=2125
These 93425 will also work. http://www.twistywristarcade.com/ram/497-93425-ram.html
Thanks for that info. I have old T&F, DD, and Commando pcb's here. Scoured them but did not find anything useful. I will burn new 4A and 7F first and see if that does the trick. If not, I guess I will head to your site a get a few parts.
 
Thanks for that info. I have old T&F, DD, and Commando pcb's here. Scoured them but did not find anything useful. I will burn new 4A and 7F first and see if that does the trick. If not, I guess I will head to your site a get a few parts.

Just looked at my pcb, guess I won't be burning new 4A and 7F. Was thinking they were eproms for some reason. I'm heading over to his place today, taking my spare pac pcb with me. I will pop them out of my working and try them on his, see how that goes.
 
OK. We swapped out the color proms at 4A and 7F with working ones with no effect. The 2C ram is MCM2115- that's what it is on my working pcb. Here is a vid of the game play. Two red ghosts and two blue ghosts and they turn yellow when you eat a pellet. Also the cherry can't be fully seen.

93415, 93425. 2125 are very common. If you have some old boards laying around you might be able to find some that are socketed. It is very rare to see them socketed on a pac board unless someone has installed them. You may want to check the color proms while your at it. They are located at 4A and 7F.
If you change out the 2125 dont worry yourself about the heatsinks. They really are not absolutely needed on these.
I have a good deal on 2125 pulls. https://www.twistywristarcade.com/search?orderby=position&orderway=desc&search_query=2125
These 93425 will also work. http://www.twistywristarcade.com/ram/497-93425-ram.html
 
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Ok. I have eliminated the color proms @ 4A and 7F. No change. Also swapped out 2C and still no change.
Just swapped out and socketed 2A & B as well. Nothing. I porobed the 2 LS194 next to 4A as suggested by Riptor and they probe good according to my good spare pcb. I also checked the small row of resistors next to 7F and they are all good. I must note that this is a modded board with the extra roms at 6P & N. Not sure if that makes a difference as the game works fine except for this color issue with the ghosts.
93415, 93425. 2125 are very common. If you have some old boards laying around you might be able to find some that are socketed. It is very rare to see them socketed on a pac board unless someone has installed them. You may want to check the color proms while your at it. They are located at 4A and 7F.
If you change out the 2125 dont worry yourself about the heatsinks. They really are not absolutely needed on these.
I have a good deal on 2125 pulls. https://www.twistywristarcade.com/search?orderby=position&orderway=desc&search_query=2125
These 93425 will also work. http://www.twistywristarcade.com/ram/497-93425-ram.html
 
Last edited:
Just checked all the traces around these chips and can't find anything wrong. Changed the sockets on 5E and 5F and still nothing. Is there something else that can control the color of these ghosts?
 
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