Help! I cant get my Wells K7901 to sync!

Anthony605

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I have a K7901 with a perfect burn free tube. I bought a super clean chassis (P447 if that helps) about two years ago. I tested the monitor out with the new tube. The picture was PERFECT!! After testing it out I put it away in storage. Today I tried to use it for my Berzerk project. The Berzerk is running on a JROK board.

Anyway, I could not get it to sync. The picture is scrambled and rolls. I think the pots may be at fault as when I tried to adjust vertical hold there is a spot on the pot where the picture just disappears. Can someone confirm that the pot(s) are most likely at fault? If so, does anyone sell a "shot gun" kit for the pots?

I know it is the monitor for sure because I plugged another monitor in and the picture is all good.

I tried to attach pics of the chassis but the upload failed.

Thanks!
 
Is your video plug a 6 pin molex only, or do you have a 6 and a 3, or even a 10 pin molex plug going to the video/sync of the monitor?
If you used the same type monitor then i would say you have a monitor problem but if the other test monitor was diff. then i would hook my video up the first 4 pins from bottom. then move the sync wire to the 10 position on top of row of pins and try that.
79xx wells do not like neg sync in the positive sync positions 5 and 6 that some monitors hook up both to neg composite sync.
always hook up video in right spot and then move sync to last position and sometimes you may have to jumper 9 and 10 together to stop a top curl or even take out the 9 position to straighten the picture. monitors be weird sometimes with different game boards. thats life.

good luck.
 
i have part's, shoot me a PM.

look and wiggle the pot to see if it is broken.

make sure there is no component leg on the bottom of the chassis bent over and touching something it is not supposed to.

Peace
Buffett
 
I didn't try to move the sync pins around. When I used the other monitor I just scooted the two games next to each other. The video cable was long enough to reach the other game.
 
probably worth noting, JROK's boards run either CGA or VGA modes, at least the Multi-Williams does, so I imagine the Berzerk does too. verify it's not set to high res.
 
Duh! My bad on this one. I PMed JROK. He told me to take the symc wire from his board and link it to H- and V-. That worked and the picture is perfect!
 
Duh! My bad on this one. I PMed JROK. He told me to take the symc wire from his board and link it to H- and V-. That worked and the picture is perfect!

it happens.. glad to see you got it working. good job.
 
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