Donkey Kong Video Question

wontwa

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Hi,

As long as I've owned my DK, intermittently the monitor would start showing a scrambled image. I posted this question a long time ago, and was told that it was likely losing sync and to check the two adjustments on the video board (I have the 2 pcb set) - this didn't resolve the issue, and over time the situation got worse.

It finally became where if the game was on for about 5 minutes, it would lose sync and play blind - I could flip the on/off and it would restart fine, but the time frame that it would work properly would shorten increasingly each time I restarted the game.

I have since purchased a (supposedly) known working EZ chassis, and am getting the same scrambled image from the word go with no intermittent working Turning it on and off made no difference. Assuming at this point that I might have a bad board, I purchase a known working board from a reputable seller here - same scrambled image. You can occasionally make out words on the screen and images from the game in the scrambled images.

So - two different EZ chassis' and two different pcbs. I have the feeling at this point that the PCBs are likely fine as the game plays blind with both (and I tried adjusting the 2 adjustments on the new pcb video board to no avail). I double checked every cable connection and everything appears to be fine.

Is there something obvious from the photo that I might be overlooking? Any ideas where to start troubleshooting this?

Thanks!
 

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It appears H-sync has drifted probably from capacitor aging or resistors changing value over time, there is a pot in the middle of the monitor board that adjusts the H-sync, the pots on the D.K. board are positioning pots unless they are broken in which case you will lose sync entirely, also appears that you have too much blue but that is another issue.
Dick
 
I have the same issue and I have a question can you move this while the game is on like you can with sound and brightness or do you need to make sure its unplugged and the monitor discharged?

Thank you;
 
You can make these adjustments when the game is on. Just make sure you're using a plastic tool to make the adjustments - you don't want to short anything to the chassis.
 
Ok I was able to get the picture back up but it will not hold the picture is will either keep moving horizontally or vertically anyone have any suggestions?
 
Ok I was able to get the picture back up but it will not hold the picture is will either keep moving horizontally or vertically anyone have any suggestions?

Is this a machine that was working and now is not? Or is this a new to you machine or a machine where configuration has changed (swapped monitor) to introduce problem?

If the latter, then it sounds like the sync may not be hooked up correctly.
 
I'm not as technically inclined as Buffett or Darth, but I can tell you my experience and what's worked for me.

I had a DK Jr. cabinet with a problem holding horizontal synch. If I could get it dialed in it was generally okay but it would fall out of synch and be VERY difficult to dial in. Not only that but the H-Hold being off would cause the monitor have a high pitched squeel and to shut down.

I got a new H-Hold pot from Buffett and that corrected the probelm and made the H-Hold much much easier to adjust.

Also, just last weekend I was swapping out boards (from Popeye to Mario Bros.) and Mario was giving me a nasty diagonal roll. I tried adjusting the H-Hold to no avail. It turned out that my edge connector harness wasn't fully connected and adjusting that corrected the problem.
 
Also, here's a tip for adjusting H-hold. You can use the reflection in the screen from the tinted bezel as a sort of mirror so that you can see whether your h-hold adjustment corrects the issue as you turn the pot. This is much easier than making a small adjustment, walking around to check the monitor, and repeating.
 
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