(this is partly to ask some questions, and partly to help others with a similar issue)
Hey folks,
I have a Ms. Pac-Man PCB that was working fine a few months ago, and I put it in storage (cardboard box with anti-static bubble wrap). I pulled it out over the weekend and it did not have sound. I have it connected to a Retroelectronik JAMMA supergun, not a cabinet. I tried some basic troubleshooting from a forum / web search (e.g. getting static when touching the amplifier solder points means that part is working), but that did not find the problem. All I have is a multimeter, so I couldn't get too much information from the board.
Looking through the Midway troubleshooting guide*, I found all the parts that could result in no sound (and no other issues), and there are quite a few: 1K, 1L, 1M, 1N, 2K, 2L, 2M, 3K, 3L, 3M, 10A (the amp). I do have another Ms. Pac-Man with working sound, so I could start replacing parts to find a failed one. Having never had to desolder before, I just tried swapping the two socketed ICs: the sound PROMs at 1M and 3M. Fortunately that did the trick: I put the 3M from the working board to the non-working one and the sound came back.
Hopefully that will help someone with a similar issue, but now the questions: Is it common for PROMs (and especially these PROMs) to fail? Is there any physical treatment of the board that would make such a failure more likely to occur, or just bad luck?
Last but not least, I would like to get that 3M PROM replaced. Is there someone here on KLOV who sells such PROMs? I tried searching, but didn't find anything relevant. If not, I can go with an eBay seller (looks like $10 + shipping).
Thanks!
- Mauricio
* Link: https://www.arcade-museum.com/manuals-videogames/P/Pacman-Troubleshooting-Guide-Part1.pdf
Hey folks,
I have a Ms. Pac-Man PCB that was working fine a few months ago, and I put it in storage (cardboard box with anti-static bubble wrap). I pulled it out over the weekend and it did not have sound. I have it connected to a Retroelectronik JAMMA supergun, not a cabinet. I tried some basic troubleshooting from a forum / web search (e.g. getting static when touching the amplifier solder points means that part is working), but that did not find the problem. All I have is a multimeter, so I couldn't get too much information from the board.
Looking through the Midway troubleshooting guide*, I found all the parts that could result in no sound (and no other issues), and there are quite a few: 1K, 1L, 1M, 1N, 2K, 2L, 2M, 3K, 3L, 3M, 10A (the amp). I do have another Ms. Pac-Man with working sound, so I could start replacing parts to find a failed one. Having never had to desolder before, I just tried swapping the two socketed ICs: the sound PROMs at 1M and 3M. Fortunately that did the trick: I put the 3M from the working board to the non-working one and the sound came back.
Hopefully that will help someone with a similar issue, but now the questions: Is it common for PROMs (and especially these PROMs) to fail? Is there any physical treatment of the board that would make such a failure more likely to occur, or just bad luck?
Last but not least, I would like to get that 3M PROM replaced. Is there someone here on KLOV who sells such PROMs? I tried searching, but didn't find anything relevant. If not, I can go with an eBay seller (looks like $10 + shipping).
Thanks!
- Mauricio
* Link: https://www.arcade-museum.com/manuals-videogames/P/Pacman-Troubleshooting-Guide-Part1.pdf

