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Original pacman was working fine until moved

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djhurt1

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I hauled this home after buying and it was working fine before the move. It now has a distorted screen but game starts and plays fine otherwise. Initially I checked and cleaned the main edge connector and this resolved the issue for a few days only for it to return. I've then fiddled with some of the Pots on the monitor chassis except for the color Pots but nothing seems to bring the screen back to normal. I'm attaching a pic of the screen. It does have what I think is a filter board between the main PCB edge connector and the harness and I've tried removing that with no effect. Edge connector looks really good IMO. Any suggestions?

IMG_20241220_191152_8.jpg
 
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Is this a static image, or does it move?
 
djhurt1 said:
@rewrite It moves. The attract sequence works and you can start a game.
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I'm sorry, I mean uhhh. Does it move like it can't sync the image, or does it sit still and you can play in the background?

Maybe a quick vid uploaded to google photos or youtube and linked here would answer a lot of questions.
 
rewrite said:
I'm sorry, I mean uhhh. Does it move like it can't sync the image, or does it sit still and you can play in the background?

Maybe a quick vid uploaded to google photos or youtube and linked here would answer a lot of questions.
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Geez sorry I misunderstood. It is not moving. So the only thing moving on the screen is the animated stuff that's supposed to be. But you just can't make it out what it is and it appears that they exist in multiple parts of the screen. Like it's duplicated over and over if that makes sense? I'll try a link to see a short vid of it here: https://drive.google.com/drive/folders/1jH61tyB9TJJaaiGzsLy0dRUf47A1W-Aa?usp=sharing
 
Whoaaaa this one is fun.

It's definitely not the monitor, that's for sure. Which is the part I'd have been better suited helping you with, lol.

Have you checked the voltages while it's running?
 
rewrite said:
Whoaaaa this one is fun.

It's definitely not the monitor, that's for sure. Which is the part I'd have been better suited helping you with, lol.

Have you checked the voltages while it's running?
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I have not and I haven't even downloaded a schematic or manual. Any particular area you suggest to check off the top of your head?
 
djhurt1 said:
I have not and I haven't even downloaded a schematic or manual. Any particular area you suggest to check off the top of your head?
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You can check off of any TTL chip. 5v and gnd.
 
XtraSmiley said:
I have no doubt the brilliant minds of A-P tech can figure this out, BUT, since this is an older PCB, the group that might be quicker for the answers are over on KLOV, the, ahem, older generation arcade game guys (where I got my start too, so I'm old).

https://forums.arcade-museum.com/
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Funny you mentioned that site. I used to be a member there but it had been too long since I logged in apparently. Any idea how you get back into this super elite club 😉
 
some near 14 years ago, the owner of the banquet hall my wedding reception was at (RIP my marriage) asked me to fix a couple video games. the Pac-Man had my jedi master's sticker on it, he sold it to them. LOL so what wound up happening was it looked like your monitor, basically no sync. the way the 3 pin sync plug was wired had the negative composite sync running to the negative vertical sync and then bridged to the negative horizontal sync. these wires are ziptied together, right? I want to say I wound up measuring voltage there and it was dead. what happened was the composite sync wire broke off and the ziptie gave the illusion like it was still in the plug. since it had a K7203 in it instead of the original G07 I think I employed some hacky connectivity trickery and spliced it to the piece of wire out of the horizontal sync pin.

I guess the moral of the story is if you can't get the sync to lock in with the H. Freq pot, inspect your wires to the sync plug. if you get voltage against the sync from video ground then perhaps you have a broken H. Freq pot?

EDIT: forgot my bridged sync wire visual aid (these may have been new plugs, you can see the double wire is in the horizontal sync spot)

g07 bridged sync.jpg
 
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Thanks for the info. everyone. I'm tabling this project for now. Got too many other things to get done.
 
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