Ms pacman pcb freezing after 4-5 minutes

kjoel

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Hey guys,

I have a ms pacman cab that is freezing up about every 3-7 minutes always during game play. What i see that needs fixing immediately. Fuse holders that holds the 4 fuses is rusty and power cord was cut at one time and was spliced and put back with electrical tape. Also test wires are not wired so i did not get it to test the pcb. Wiring is hacked by the main pcb edge connector.

What i will do next is replace the fuse holder and fuses, recrimp the bad connectors and replace the power cord. Also i will rewire the test button and try and test the pcb. If all fails i will rip out all the damn wiring and wire it up jamma with an adapter.

I did not have my meter or tools with me onsite at the time as i was unaware the game was down.

Has anyone seen this issue of the pcb freezing gameplay ever 5 or so minutes?
 
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Yes. Could be the fuse holders, edge connectors, or simply a bad IC chip - most likely the Z80.

Being a Ms Pac it could be a ribbon cable issue... Pull the daughter board, plug the Z80 into the CPU socket on the main board and see how it runs.

It'll look like a regular Pac Man but with the Pac character running on his lips because of the Ms Pac character ROMs, but you can at least run it.

RJ
 
I do have 3+ ms pac pcb's on hand. I will replace the fuse holders and connectors first then swap out the daughter board. Thanks for the great tips, forgot about the daughter board entirely and learned about the z80 trick.

Thanks again
 
I replaced the power cord, fuse holders and brought 3 boards sets with me for parts. I finally isolated and seemed to resolve the issue to bad ram chips right under the small vram board. Had my buddy test play the game and it went through about 7-8 boards with no freezing issues. It always seemed to freeze when ms pac was caught by the ghost. Took a few hours to get this resolved. Hopefully it does not re-occur.
 
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