Pacman motherboard issues, garbage on screen

DaveyPocket

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Hello everyone (I'm new here)!

Anyway... I am having issues with the motherboard on my Pacman machine. When the game is powered on, the game goes through it's startup test, shows the white grid, then the game starts. The only problem is that there are small flickering blue vertical lines covering the screen. When the game is in service mode, those lines change to white. When the image is frozen (dip switch 8 is on) the lines go away, but sometimes two or three flickering lines show up on the top of the screen. This problem also seems to affect the sprites. Two of the ghosts are just a few flickering lines. Finally, sometimes one small part of the screen might start to curve (happens shortly then goes away).

Otherwise, the game runs fine and the sound is fine.

Pictures (Sorry if they're a bit blurry):

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Hi Davey, welcome! Well, the very first thing I would do is remove and clean the harness and edge connector. If you have one of those RF filters on there, toss it out (or put it in a drawer). Rubbing alcohol on a q-tip usually cleans the contacts pretty well. Sometimes for the harness I use an old business card with alcohol on it or an old toothbrush. Attach everything again and see if just cleaning the contacts has any effect.
 
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Also, take each socketed chip out, clean the legs (carefully) with a small cardboard nail file, and put them back in....
 
Make sure the vram card is seated good. You might want to pull the card off and make sure the legs are not corroded.
If you have a filter board between the wiring harness connector and the pcb, remove it.
 
I got it working! I followed what modessitt said, I took out every chip and cleaned the contacts. (I did it before but I think doing it again helped). Thanks everyone!
 
Davey,

Sometimes you can get similar looking issues if you have a broken resistor pack on the board. There are some versions of those packs that are pain in the rears on Pac Man boards.

Glad to hear you got it fixed!
 
Cool deal, if your roms are the old black masked roms you should can those and upgrade to real eproms. If I get a board with them on there I immediatly pull them before doing anything else.
 
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