Pac-Man 6pac issues

Jr. Pac

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Donor 2012, 2015
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I was playing Pac-Man Plus on the 6Pac last night and I started noticing some random static that gradually got worse. The videos tell all. Anyone have a clue?

3 videos:

 
Reseat the Six Pac daughter boards. They eventually work their way loose due to a combination of heat cycles and vibration and need to be reseated. I have the same issues with my Six Pac.
 
Will try. The character ROM has some repairs on the legs so that might be it. It's odd how it's happened so suddenly.
 
Either a problem with the character roms or possibly a connection issue with the vram card. Since you seem to have issues with the character rom I would start there.
 

New video.. the correct graphics cut in and out. It's not a 6pac issue as I've tried it stock with the exact same problem. Everything socketed has been reseated, the vram addresser and Sync Buss controller have been reseated, board cleaned, even the edge connector cleaned and reseated. Anyone have a clue? I'm thinking about getting the Twobits ABC diagnostic kit?
 
I had bought a pac harness off fleabay once, and they hard the parts side marked on the wrong side of the edge connector. Took me a couple minutes to figure it out after I plugged it in, but after putting it the right way, it would act the exact same way. Work for about 5 minutes and then start cutting in and out with static and/or an image of gibberish that looks like it's booting. I don't know which it was, but I swapped out the small board above the cpu and also the cpu and it works great. This doesn't necessarily mean the same problem, but the same symptoms.
 
Alright, I've found something. When it's cold (~50 degrees) and I haven't had the machine on for many hours, it works for about 10 seconds, then gets some garbage near the ghost house (still playable) then everything glitches (still playable) until everything looks like the videos above.

I've ordered the Z80 Sync Buss and a new socket (haven't got it yet). Anyone have any other feedback?
 
I've seen working Pac boards go for $75 shipped pretty often.

You might be able to sell your busted one for $30.

Not bad math if you ask me..
 
I could do that, however I prefer to keep the PCB original if it's nice. It'd be likely cheaper to just repair it.
 
I have a pac-man PCB that will seemingly randomly render all sprites as garbage. They are slivers of proper sprites, but their positions are completely screwed up and the slivers are spread out everywhere. Maybe this is also a sync bus problem?
 
I could do that, however I prefer to keep the PCB original if it's nice. It'd be likely cheaper to just repair it.


ah- I was talking about getting an ORIGINAL replacement for $75.

Or you could just monkey with yours and you may stumble across the problem.
Those little cards that fit into sockets on the PCB - one is the VRAM addresser and one is the sync bus controller. You could try wiggling them or reseating them in the sockets, but they have very flimsy pins on them.

Can break easily and the replacements are $20 or so.

The game does the same thing whether the 6pac kit is plugged in or not, right?
 
I know. I meant the technically original PCB that likely came with the game, not worth it to get a new PCB (I'm already technically broke anyways).

I have done everything from cleaning the board, reseating socketed chips, etc. It does it with and without the kit so the 6Pac is not the issue. I've already ordered a new Sync Buss. Vram addressers are $40 IIRC.

FYI the Sync Buss and Vram addresser have sockets between them and the sockets on the motherboard so flimsy pins on them shouldn't matter.
 
Here is what I've done to help fix static and boot issues on my mrs pacman and pacs in the past:

Removed the pcb that connects to the harness and PAC pcb.. It's pretty useless and causes more problems than its worth.

Replaced the fuse holders at base of cab. This is important as the brass ones loosen up over time.

Replaced the main harness connector and repin'd it

Replaced the pcb power connector

If your having a lot of issues with the 6-PAC I sold you, drop it in the mail and I'll replace it for free man :)
 
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