DK Jr Sync Issues

Rngenius

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My DK Jr has been having some sync problems of late. Sometime I will fire it up and will work fine. Seems to be linked to the vertical position pot on the pcb. If it's working, and touch that pot, the game goes out of sync. I put a new 50k pot in but it did not fix the issue. Any ideas?
 

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South Dakota! You are losing horizontal sync in your picture. Have you adjusted the H sync on the monitor? You might be on the edge of the adjustment range.
 
It's has nothing to do with the monitor. I plugged in a vs game that I have right next to this one directly into sanyo on faulty dk jr.
 

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Get your logic probe out. Could be a lot of different components if it is not the pots on the pcb and not adjustments on your monitor.
 
Thanks Mike, my last suspect could be the wiring to the monitor. This one has a bob roberts classic harness. Looks like the Sanyo has 2 grounds and the Bob Roberts harness has only one video ground. Its wired with both grounds from the monitor tied to the one video ground to the pcb.

I think I have another classic era Nintendo PCB that I will try to find an plug in. That would help with diagnosis. If she's injured, I will send it to Mike's Arcade. Thanks for the help.
 
It's has nothing to do with the monitor. I plugged in a vs game that I have right next to this one directly into sanyo on faulty dk jr.

The monitor sync needs to be adjusted for each gamme signal. Each PCB can be different, that's why you have a range of adjustment. The monitor could be randomly adjusted perfectly for vs, but need to be tweaked for JR. As components age and wear, you might have to adjust the controls to keep a game synced.
 
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The monitor sync needs to be adjusted for each gamme signal. Each PCB can be different, that's why you have a range of adjustment. The monitor could be randomly adjusted perfectly for vs, but need to be tweaked for JR. As components age and wear, you might have to adjust the controls to keep a game synced.

That doesn't explain why the game will work ocasionally.
When working, if you so much as touch the vertical position pot the game loses sync.
 
I dialed in using the pot at vr451. Thanks guys. I'm an idiot.

Yeah sync is a weird thing. Very hard to perfect glad you fixed it though. And if you haven't, sync issues can also be caused by bad caps, security0001 a great seller has the cap kits for 20ezs. I'd recommend capping sands because all the ones I've had have needed caps but thats just me :)
 
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