Ms pac issues

daxwell

Member
Joined
Nov 18, 2010
Messages
96
Reaction score
5
Location
Monroe Township, New Jersey
I have a Ms. Pacman that was running pretty well until recently when it started to display an image similar to one on the arcade game over pacman troubleshooting page. It has fast moving short vertical lines but no high pitch squeal coming from the monitor. The game is actually playing even though it doesn't show up. If you follow the pattern, you can eat the power-ups and hear Ms. Pacman die. Id this the same issue as on the the arcade game over site, and if so, how does one fix it. If this is a different issue, is it the monitor? I am just a game owner, not a hobbyist so I have very limited repair skills.
 
Is this the image you were referencing?

Image6.jpg
 
It's not the vram addresser card. That card is strapped to the main board in my machine. I don't think it's loose, so I didn't try to take it out and reseat it. What is a monitor sync issue and how can I try to fix that.
 
According to the arcade game over site it is:

Fast moving short vertical lines covering screen. High pitch squeal from monitor. Caused by shorting 6 MHz clock signal to other chip pins. Also caused by PCB frequence pot not adjusted.

2B shorted 6 MHz clock signal p14 to p9,10,11,12,13 or 15. OR 2A short p14 to pad next to it. OR 1E,2E short p2 to 1,3,4,5,6,8

I have no idea what that means or how to fix it.

If nobody has any suggestions, I'll try recapping the monitor.
 
yeah man- I'm thinking that one is just a case of misadjusted horizontal sync.

Start poking around in the back of your monitor looking for a control labeled such- not 'misadjusted horizontal sync', look for 'horizontal sync'.

Now don't come back and post that you only see:
horz sync OR
horz OR
h sync

or you will start getting <more> snappy replies...

It could be a board issue too, but I'd start with the user-adjustable monitor controls.

Kerry
 
I looked for a horizontal sync adjustment. I couldn't find any dials (Pots?) labeled that way. There is a spot on the board labeled HOR. VERT. OSC. but there is nothing that can be adjusted by it. There are 4 pots on the bottom left and two above them, but they really don't have labels that I can read. The label on the chasis says it is a Wells Gardner 19K4961 if that helps.
 
Yes, that's very helpful.

In the "2 above them" pots, your horizontal hold adjustment is on the left.

See this pic:
 

Attachments

  • K4900.jpg
    K4900.jpg
    77 KB · Views: 12
I tried both directions - no change. The image shifted a little, but it was the same as the picture that you posted. I'll try a cap kit and if that doesn't work I'll look for someone to repair the board. Thanks for your help.
 
Back
Top Bottom