Pacman doesnt like any of my monitors

jcterzin

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'ello 'ello. So says Austin powers.

My pacman doesnt like any (either I should say) of my monitors and all I get is scrolling garbage on the screen (see attachment). The game plays blind and the monitor works as I tested it on my outrun; So its definitely gotta be the either the pac pcb or the way im connecting the monitor to the pac pcb. Ive tried pretty much every combination of connections from the harness to the monitor that I could think of. Ive moved around the sync wires, shifted the connector one pin down for the sync... The monitor is a WGK4903.

Also, I was looking over at some pictures of what the pac pcbs look like and some have extra boards connected that mine doesnt have. Would that make a difference?
 

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fo sho.

the first image is my pcb. The second (with the orange circles) is another pcb I found that has three additional boards that mine does NOT have. What are these boards and do they affect the game from showing up on a monitor? Like I said, the game I have plays blind but wont show up on the monitor screen.
 

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  • Bally Ms Pac Man PCB.jpg
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Your first picture is a Pacman board with the dreaded orange IC sockets. They are well known for failure and should be replaced. The chips plugged into the orange sockets are the V Ram Addresser and Sync Buss Controller which indicates your board is an early run. The chips may be ok, but the sockets are bad.

The other board you have is a Ms. Pacman board. It has two small circuit boards plugged into those sockets: a Sync Buss Controller board (replaces the no longer available sync buss controller chip) and a V Ram Addresser board (replaces the no longer available V Ram Addresser chip). The third board connected by a ribbon cable is the Ms Pac daughter board that turns a Pac into a Ms Pac.

Arcadeshop is now selling replacement/reproduction sync buss controller boards and V ram addresser boards that use modern parts & are considerably smaller than the originals:

http://www.arcadeshop.com/parts.htm#Chips
 
Your first picture is a Pacman board with the dreaded orange IC sockets. They are well known for failure and should be replaced. The chips plugged into the orange sockets are the V Ram Addresser and Sync Buss Controller which indicates your board is an early run. The chips may be ok, but the sockets are bad.

The other board you have is a Ms. Pacman board. It has two small circuit boards plugged into those sockets: a Sync Buss Controller board (replaces the no longer available sync buss controller chip) and a V Ram Addresser board (replaces the no longer available V Ram Addresser chip). The third board connected by a ribbon cable is the Ms Pac daughter board that turns a Pac into a Ms Pac.

Arcadeshop is now selling replacement/reproduction sync buss controller boards and V ram addresser boards that use modern parts & are considerably smaller than the originals:

http://www.arcadeshop.com/parts.htm#Chips

interesting. So basically what I should try first is replacing the IC sockets. Where can I find those? Ive never replaced any of those before. Also, and just for reference, If I do need to replace those chips in those sockets I should just buy the boards instead of finding chips?

I dont know much about how the pac works but I take it that the 'sync buss chip' is probably at fault here, is that a correct assumption?
 
interesting. So basically what I should try first is replacing the IC sockets. Where can I find those? Ive never replaced any of those before. Also, and just for reference, If I do need to replace those chips in those sockets I should just buy the boards instead of finding chips?

I dont know much about how the pac works but I take it that the 'sync buss chip' is probably at fault here, is that a correct assumption?

No... chances are it's a bad counter in the sync chain... possibly a bad vram addresser.... sync bus controller has very little to do with video generation.

I've got replacement boards for both daughterboards, and could fix it and upgrade it to sixpac if you're interested.
 
Basically it's saying that your symptom is similar to not having any sync. One of the reasons they found for a board not to have any sync is if that pin on chip 2s gets grounded, the sync will be screwed up.

There's also 100 other ways your sync could be screwed up. Whatever that pin connects to might be grounded out. a Trace might be broken somewhere, or what Mark suggested could be screwed up. It could be as simple as the Sync pin is dirty.

It's like a needle in a haystack if you don't have a systematic way to test what's doing what.
 
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