Donkey Kong (Sanyo EZ?) monitor issues

jamesmallen

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Yesterday I picked up a Donkey Kong that I saw on Craigslist in pretty good shape. The game appears to play quite well, though I can't seem to find any self-test procedure to verify that there aren't any problems with the board. However, this post isn't about the board - it's about the monitor. I guess it's a Sanyo EZ?

The monitor appears to have a crisp picture, practically no burn-in, and all the gain/color controls work fine. However, every 5-10 seconds or so, the picture "shimmies" - squiggling a bit left to right. This is a very brief shimmy, then the picture goes back to normal. I opened up the cabinet to investigate the issue, and it sounds like there is a clicking or snapping noise coming from somewhere on the right side of the monitor board. I think it might be this silver thing that's circled in the picture below, but I can't be sure.

p1030662i.jpg


And here's a closeup of the silver thing:

p1030663m.jpg


Any ideas of things to check? I've never done any work on monitors before other than adjusting pots, so I'm obviously a little nervous, but if anyone has a clue of where to start, I'm very interested in expanding my monitor knowledge!
 
the ticking is most likely coming out of the flyback, not the HOT that you have circled.

it could also be going into hv shutdown too. test the b+ and see what you get.
 
You're right, the ticking is coming out of the flyback. I tested B+, and I'm getting 118, which is about 10V higher than I believe it's supposed to be. However, now I have a dumb question - I can't figure out how to adjust the B+ pot (VR601). I don't have any TV alignment tools handy, so I fashioned something out of a set of chopsticks electrical taped together to add length, with the end of one whittled into a blade, but I can't seem to get the pot to turn in either direction. I am chalking this one up to bad craftsmanship on my part. I gather the appropriate tool is something called a TV alignment tool... is there any place that would sell a suitable tool locally?
 
I'm getting ready to blame the pot now. I can't turn the thing using a screwdriver with any of my slotted bits - all it does is wiggle the pot around left or right. I found a picture of the way the B+ pot is supposed to look here: http://arcadecontrols.com/BBBB/g07pot.html. However, mine is looking a bit gummed up/corroded. Is there something I can do to loosen it up, or am I going to have to pull the board out and replace the pot?
 
that white shit, is an adhesive to keep the pot from moving. scrape that crap off of there, it is not needed.

That said, it was glued at the factory, and was almost certainly pre-adjusted to 108v when glued. If it's up to 118 I'd guess should do a cap kit/rebuild on the sucker. While you're at it, replace that B+ pot. :)

Still, if you can adjust it down for the time being, that would be a good thing.
 
Well, I ordered the deluxe monitor + sound board cap kit and a new B+ pot from Bob Roberts. This'll be my first attempt at such a kit, and from what I hear it's a doozie to work on. Any advice for getting the chassis out to work on it? Do I have to take out the tube as well, or is there some way to pull the chassis board separately? I've already discharged it and disconnected all the parts that seem to easily disconnect, making sure to take plenty of pictures first. It seems like accessing the board is still going to be a pain, though...
 
I take the entire monitor (tube/frame/chassis, the whole shebang) out and put it on the work bench. It's a lot easier to get at the chassis that way IMO.
 
Well, I ordered the deluxe monitor + sound board cap kit and a new B+ pot from Bob Roberts. This'll be my first attempt at such a kit, and from what I hear it's a doozie to work on. Any advice for getting the chassis out to work on it? Do I have to take out the tube as well, or is there some way to pull the chassis board separately? I've already discharged it and disconnected all the parts that seem to easily disconnect, making sure to take plenty of pictures first. It seems like accessing the board is still going to be a pain, though...

The Sanyo's aren't that difficult to do at all. My first few capkits were on Sanyo's and other that a little tedious dissassembly and reassembly they are easy.

1. Remove the monitor from the cabunet.
I find it easiest to pull the bezel and take out the 2 bottom screws that hold it in. Remove the back door and take out the 2 upper mount screws and the upper bar support screws. Pull out the bar. Make sure your AC, Audio, Video and speaker wires are disconnected and pull the monito out the back.

2. Discharge the tube. Wait a few, discharge again.

3. Carefully disconnect the yoke, audio board, neckboard, hv connector remove the flyback cover, a few screws and gently slide the chassis out the right side (looking from the back) out and do the cap kit.

4. Reassemble the chassis, center all adjustment pots on the pot board and the neck board.

5.Fire it up, check and adjust the b+

6. Adjust color, center, brightness and volume as needed.
 
All right, I bit the bullet and installed my first cap kit - a deluxe kit (including audio board) from Bob Roberts. It ended up being a lot easier than I expected! I also replaced the B+ pot.

After adjusting the pot, my B+ voltage is at 108.0 and steady. However, I'm still getting the clicks every 15-20 seconds or so once the monitor warms up, which I'm pretty sure are coming from the flyback. Is my only course of action to replace the flyback, or do I have other options? When I had the board out, I gave the flyback a once-over, and didn't see any visible cracking or anything like that...
 
The metal plate on the side of the flyback with the HOT screwed to it is what I'm referring to. If you watch the arcing in the dark you can usually see what it is arcing to. Arcadecup is where I get mine.
 
Well, I wasn't aware there was supposed to be a cage around the flyback! This cabinet's flyback just looks like this:

http://www.arcaderestoration.com/graphics/tutorials/capkit/pcbscrewsbig.jpg

As opposed to being in a cage, like this:

http://www.arcaderestoration.com/graphics/tutorials/capkit/dischargebig.jpg

Is it incredibly dangerous to have it without a cage? And does anyone have any recommendations on places to get a flyback? I see arcadecup.com has them for $29 shipped...

I'm not sure the cage is the issue. My DK doesn't have one and I've seen lots of pictures of other machines that don't have them.
 
The replacement flyback from Chad works like a charm. No more sparks!

Now I've adjusted the cutoff/gain settings so that everything is prettier, and centered the image and everything. However, it seems that I can't adjust the horizontal width. I guess I'm supposed to stick something inside the little coil, but I don't see anything inside there. I can shine a flashlight through it, and there's nothing but a cylinder. It's not a huge deal - it's just not stretching to fill the longest part of the tube. If it's something simple, though, I'd love to fix it.

By the way, thanks to all for all the help you've given so far, especially dokert!
 
The replacement flyback from Chad works like a charm. No more sparks!

Now I've adjusted the cutoff/gain settings so that everything is prettier, and centered the image and everything. However, it seems that I can't adjust the horizontal width. I guess I'm supposed to stick something inside the little coil, but I don't see anything inside there. I can shine a flashlight through it, and there's nothing but a cylinder. It's not a huge deal - it's just not stretching to fill the longest part of the tube. If it's something simple, though, I'd love to fix it.

By the way, thanks to all for all the help you've given so far, especially dokert!

DK isn't supposed to fill the entire screen (vertically or horizontally). It should have some breathing room on the left and right, and even more breathing room on the top and bottom. In fact, I've played on a couple where people have the game stretched to fill as much screen as possible and it looks out of proportion. Its better to focus on the proportions. If you have it set right the graphics will look like they float inside the game. You won't be able to tell where the monitor stops, everything but the graphics will just look like a black abyss. If you stretch the graphics to the edge of the monitor it reveals where the monitor edge is and it ruins the illusion.


You can use MAME as a reference to check your proportions.
normal-2.gif
 
DK isn't supposed to fill the entire screen (vertically or horizontally). It should have some breathing room on the left and right, and even more breathing room on the top and bottom. In fact, I've played on a couple where people have the game stretched to fill as much screen as possible and it looks out of proportion. Its better to focus on the proportions. If you have it set right the graphics will look like they float inside the game. You won't be able to tell where the monitor stops, everything but the graphics will just look like a black abyss. If you stretch the graphics to the edge of the monitor it reveals where the monitor edge is and it ruins the illusion.

I didn't know that. If that's the case, then I think my monitor is all set. Thanks!
 
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