Ms. Pac Man screen issue

darthphunk

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Hello!

I have a Ms. Pacman cocktail cabinet that I was having problems with. When I got it, it would power on, but the screen would be scrambled and it would not play blind. After replacing fuses, I tried again... same issue.

I sent the board off to be tested, and the person who tested it said it worked just fine.

So, I was told it may be the transformer or the edge connector. I tested the transformer with my meter, and I wasn't getting the numbers I was told I should get. Someone from the forums here (thanks CJ) gave me a Galaga power block so I can swap it with mine.

Now, the game starts... and it's still scrambled... but now it plays blind! WOOHOO!!!

So, my CURRENT problem is the screen is scrambled, and there is a hum coming from the speaker, but I can hear the game music and sound effects when I start the game.

Here's a pic...

1000255t.jpg



I don't know if this has anything to do with it, but there seems to be a wayward wire hanging from my harness. It's orange with a red chaser...

1000257u.jpg


It looks like it may be a sync wire going to the monitor... which would explain things. Can anyone help me properly identify this wire?

If that wire doesn't matter, is there something else I should check before I replace the edge connector?

Thanks!
 
your problem looks like a sync issue to me. I don't know these boards at all, I'm just going based on what the screenshot looks like :)

I'm sure it's not difficult to dig up a pinout on one of these.

Welp... after a little more digging, I found this...

http://www.ggdb.com/KB.aspx?c=Coin-Op&s=Arcade&vid=1842&kb=238

Says the Orange/Red wire is RGB Neg Sync. I'll fix this tomorrow and see if it cures my woes.

Would a video issue like this cause a loud hum from the speakers?
 
not sure about the hum, but your monitor probably makes all kinds of weird sounds if it can't sync up though.

how the hell do you even fix that? do the pins pop out of a Pac-Man harness like a JAMMA one?
 
not sure about the hum, but your monitor probably makes all kinds of weird sounds if it can't sync up though.

how the hell do you even fix that? do the pins pop out of a Pac-Man harness like a JAMMA one?

I don't think the pins pop out. I'll know more tomorrow when unplug it and take a look at it.
 
If its a hum its probably not causes by the missing sync. Sometimes missing sync will cause the monitor to squeel a little.
 
If its a hum its probably not causes by the missing sync. Sometimes missing sync will cause the monitor to squeel a little.

The monitor is definitely squealing a bit. Not as bad as before I swapped out the transformer.

Maybe I have two more problems... the disconnected sync, and the "hum bar" issue.
 
I'd say they are different issues... for the hum, you probably need to clean the fuses and fuse holder. The video is probably the horizontal sync out of wack, probably (at least partly) from the missing sync wire. If it's a K4600 it may be this issue as well: http://www.therealbobroberts.net/slanted.html (hidden course H-Sync adjustment).

DogP
 
FIXED!!!!

It was just the h-sync that needed adjustment... and KABLAMMO!!! It works!

Question though.

I did replace the transformer with a transformer from Galaga. They appear to be the same size... but there is a problem.

When the cocktail cabinet is closed, I get some pretty good discoloration. When I have it open with the monitor tilted to the side... Colors look fine.

The inside if my cocktail cabinet is not shielded like some cocktails I've seen.

Do I need to get shielding? Or will degaussing with a coil while the cabinet is shut fix my issue?

Still getting the "Hum" and now that the monitor is working I do have the slow moving black line... I'll deal with that soon.

Thanks for the help!
 
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