Donkey Kong Cocktail Repair Log - Tracking Down Image Shift

mhanlen1

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Donkey Kong Cocktail Repair Log - Tracking Down Image Shift

So DK is my first cab, and so far it's teaching me a lot about arcade repair. I'm a newcomer to arcade collecting, so this thread should be read with that in mind. Before finding my cab at a thrift store, I had never soldered, or looked inside an arcade machine before. I do have a background in A/V, but not in repair side, so I'm learning about electronic components and arcade parts as I go. Anyway I'm creating this repair log in an effort to track down a video issue I have. Hopefully if I ever find the cause, this thread will help others who may be experiencing the same thing. Here is a video of the problem.

In order to track down the screen shift that my cab has been experiencing I started by capping my monitor. A few months ago I purchased Bob Roberts standard cap kit for a Sanyo 20EZ. I purchased this for the primary purpose of correcting a screen fold. The kit fixed the screen fold, but didn't fix the image shift problem. Here are the caps that came with Bobs kit, to use as a reference to those who haven't ordered it.

1uf50v___________C302/C453
1uf250v__________C408/C467
10uf50v__________C301/C303/C406
10uf250v_________C407/C471
22uf50v__________C464
47uf10/16v________C458
100uf16/25v_______C459
100uf160v________C410/C472
220uf25v_________C469
330uf25/50v______ C468

None of the above caps are Bi-polar (or NP as they're labeled on the Sanyo board), so it's important to mind where the "+" and "–" go.

So after installing the kit, I still had an image shift. I then ordered some replacement pots for my game PCB and the Sanyo monitor both. They were sensitive to the touch, so I figured they should be replaced anyway. After replacing those, the pots were no longer so touchy, but it didn't resolve the image shift.

It was then recommended to replace C606 with is the filter cap for the B+, and it may solve it. Well since Bob's regular kit didn't include all the monitor caps, I found a complete list Dokert created for mouser in this thread (which doesn't include the C606- by the way). So for the sake of covering all my bases I ordered a C606, the hi-temp monitor cap list, and the audio cap kit (which I also didn't do the 1st time). I also tore down my PP7b power supply and made a list of all the caps I need for it, just in case. So yesterday I got all the monitor caps and power supply caps in.

My first order of business was to install all the caps that didn't come with Bob's Kit, and the C606, and the audio board (a preventative measure even though I have no sound problems). So now all the caps on the Sanyo monitor are brand new. Here are the additional ones I installed yesterday (minus the audio kit).

470uf160v____________C606
220uf16v_____________C202
1uf50v_______________C454/C166
220uf16v_____________C161
1uf160v______________C610
4.7uf25v______________C411/C462 (both of these caps are Bi-polar- the only 2 B.P. caps on the monitor)
470uf10v_____________C609
So after all of this, I still have the video problem. This would leave me to believe it's not a monitor cap issue. Despite the problem I don't regret installing the additional caps, because it improved overall brightness and made the colors richer. If I could do it again, had I would have known better, I'd have ordered a complete cap kit for the audio and video. It's really worth it to replace them all at once.

So what's next? First I'm going to reattempt adjusting my B+ after not getting any reading on it last time I had the cab apart. I think my problem is using a multimeter that isn't functioning properly. It also doesn't help that I've never used a multimeter before this project.

Once I tackle the B+, I'm tearing apart my power supply and recapping it (within the next day or two). Anyway I'll keep track of my progress here, as a help to others who have this same annoying problem.

It would be nice to have a spare board set, monitor, or power supply lying around to help isolate the issue, but I don't have that luxury. At least I'm learning more this way.

OK, I'm off to radio shack…
 
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Update: After I was taught where to place my ground lead, and how to set my multimeter correctly, I was able to see the voltage on my B+. Turns out it was 113 volts. So I dialed it back down to exactly 108, and turned it off. I let it rest for 20 minutes then fired it back up. I played several games, only to see the problem pop back up on the elevator level.

Next up... Recapping the Power Supply. Stay tuned (to those that care).
 
Well Donkey Kong wins for now. The problem still persists. Everything still works as it did before, but there still is a vertical image shift. If I'm not mistaken, it seems to have gotten worse. The whole image has a pixel crawl now, that you can adjust away for a few minutes before it returns. In fact I've lately noticed a slight left to right movement of the entire image, almost like the H-hold is sorta screwy. For a while I thought it was just my eyes, but now I see that it's not. I've replaced all the pots, so I don't have a clue about it's cause (although I'm sure it's somehow linked to the main problem)

Anyway I thought I'd share the cap list I made for the PP7B power supply, in case anyone is thinking about repairing theirs. I've broken it up into 2 parts- 1 for each board. But be careful, I made the list myself after logging the values and location of the caps on my power supply. I can't be certain that my power supply was correctly capped when I got it, so that may be a problem in itself. I have not collaborated with anyone to ensure it's accuracy, but I do know that after replacing the caps on mine everything still works like before. Without further adieu:

Side with fuse (no heatsink).
47uf16v______C38/C32/C20/C37/C31/C19/C18/C30
47uf35v______C13
330uf200v____C6/C7
10uf16v______C22

Side with Heatsink and 4 amp short fuse
3300uf10v______C27/C28
10uf16v________C34/C35/C24/C2
100uf25v_______C33/C23
47uf16v________C36/C12
1000uf25v______C21
3300uf10v______C15/C16
1000uf50v______C10
47uf35v________C11

Here is the Mouser Project ID page, if you'd like to order it from there.

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b592e3d4e6

Anyway, thanks for suggestions everyone has given in other threads. I've sure learned a lot. But for the time being, it'll just have to stay like it is. I have a suspicion that there may be some bad RAM on one of the boards, because I noticed a few are very warm to the touch. I might try replacing them in the near future. I'm hoping also that a spare cocktail will pop up around these parts for cheap so I can have extra parts.

On the bright side, aside from the weird problem, my monitor's picture looks almost brand new. Not a single instance of burn-in, and the color is awesome.
 
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I just watched the video. That looks like a hum bar to me...or some other AC interference. Is it beside of anything that sucks a lot of juice...Refrigerator, air conditioner, etc? Could be the plug it's plugged into....or a bad ground, or a weak connector in the harness. These can be tricky to track down. I had a Sega Turbo once....any game that got within 18 inches of it would have a hum bar. I couldn't set another game beside it without that damn hum bar.

Edward
 
I bought one of those outlet testers today, and it shows that the outlet is a properly grounded socket. I originally thought that it was a power problem, because I didn't notice the issue at the place where I bought it. So I cut the 2 prong cord off of the power cable and spliced a 3-prong grounded Edision on the cord because the power cord had a black, white, & green line in it. But there seemed to be no change either.

Anyway I only have the one cab. It's hooked up in our computer/home theater room, and I even experience it when I only have my computer turned on (which is opposite the room). In fact, the only major appliance that's on in the house at all times is the fridge downstairs.

But it's a thought. I actually might try unplugging everything in the room- even if it's not in use, tomorrow morning. At this point I'm open to trying anything, short of buying more parts for it.

I also rechecked my B+ tonight on the new multimeter I bought today. It read 108.9, so I dialed it back to 108. I don't think it'd matter that much since it was at 113 earlier today.
 
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I feel your pain. I'm trying to diagnose a similar problem with a DK Jr. cab. I have a left to right vibration on mine. So far I have replaced C606, Replaced the Z80 chip, replaced the pots on the PCB and tested the voltage on the power supply.

Did you replace the pots on the monitor board itself and not just that row of adjustment pots with the volume and such? I haven't replaced that Horizontal Hold pot on the monitor board yet and I don't know if that would help or not.
 
I feel your pain. I'm trying to diagnose a similar problem with a DK Jr. cab. I have a left to right vibration on mine. So far I have replaced C606, Replaced the Z80 chip, replaced the pots on the PCB and tested the voltage on the power supply.

Did you replace the pots on the monitor board itself and not just that row of adjustment pots with the volume and such? I haven't replaced that Horizontal Hold pot on the monitor board yet and I don't know if that would help or not.

If you look at the picture here, my H-Hold isn't actually on the board, it's the pot right above the left side of the "High Voltage" sticker. Anyway it's not a cap I got with the pot kit from Bob Roberts, as it seems this is not a common configuration among other DK machines. I haven't replaced it, but it still works well and is not sensitive to the touch. It seems to adjust properly as far as I can tell.

3529540682_e2af829408.jpg
 
I haven't replaced that Horizontal Hold pot on the monitor board yet and I don't know if that would help or not.

The H Hold pot could be the source of your problem.

If you look at the picture here, my H-Hold isn't actually on the board, it's the pot right above the left side of the "High Voltage" sticker.

The H Hold pot could be the source of your problem too.
 
Because my configuration isn't typical of uprights, or the picture that comes with Bob's kit, I don't know what you would need.

I checked the pot on my DK anyway and it's listed as a 302 n- which I think means 3000k pot. Also it's a pot thats designed to be mounted parallel to the board, so the leg spacing is different than the other pots that came with the kit.

I couldn't replace my volume control knob either because it's this type of pot.

Actually, come to think of it one of the pots that came with the kid didn't match with the numbers of the one on my monitor- but I installed it anyway. I hope that wasn't the wrong thing to do.
 
I checked the pot on my DK anyway and it's listed as a 302 n- which I think means 3000k pot. Also it's a pot thats designed to be mounted parallel to the board, so the leg spacing is different than the other pots that came with the kit.

Just an FYI....302 = 3000 ohms....or 3K.....not 3000K, which is 3000000 ohms :)

Edward
 
Mhanlen1, did you happen to try and adjust the H. hold pot on the monitor chasis its VR451? Move the pot to where the picture is all out of wack, and then re-adjust it to a good picture and see if that fixes the problem?

I just did this and it fixed the problem in mine for now, its only been running 15 mins or so, but I did also swap boardsets. The thing is though, that it was shifting on the other boardset I just put in before I adjusted VR451.

I have 3 diffrent sets, a 4-board like yours, a 2 board, and a double donkey kong which is a modified DKjr 2 board. I had the shift with the double DK, and the 4-board.

I have the 2 board in there now seeing if the shift will return.

I'm not to worried about fixing the shift in mine because it doesnt last long, and doesnt bother me that much. I just want to throw these ideas out there and try and help so you dont buy a new boardset and still have your original problems.
 
i get it as well, and i've sort of come to deal with it. but, i've gotta put in an order with bob roberts soon, so i may just recap the damn thing just to make sure that's all done.


question, cause i've wondered about this. does anyone with an UR instead of a cocktail have this problem? and if so, is it 4 board or two board. i've wondered if it could be an interference problem in the cocktail, like how some midway cocktails get humbars from the close proximity of the transformer assy.
 
Yup, I had this with my upright. Ive had it on a double donkey kong board, and a 4 board-set donkey kong.

I did the delux cap kit from bob, including the sound board, and replaced all of the adjustment pots on the adjustment board to fix an unrelated problem and the shift was still there.

I seemed to remedy it just now by adjusting the H. hold pot on the monitor chasis and it has yet to return, and I put the double donkey kong back in. (read above post)

When I had this problem it seemed to go away the longer I played so I am going to let the machine sit shut off for awhile and see if it comes back when I turn it back on.

I can live with it if it does come back. I look at it like this, I have an xbox 360 that died after 2 years of use, this thing was made in 1981, so if it is still working after that long, I consider myself lucky. ; )
 
It's always been fixable by adjusting the pots. But the fix was always temporary. The H-hold on my particular cocktail isn't on the monitor board, but it's actually right near the other pots, so it's pretty easy to adjust. But yeah, I've adjusted the hell out of every single pot on the game board and the monitor, only to have it return at a later time.

It shouldn't be that big of a deal, but for some reason it bothers me.

Oh well. I'm not going to invest a lot into another board, but if I come across one pretty cheap I'll pick it up. After installing the correct style P2 joystick last night, and getting the coin mech up and running, I'm happy for now. All I need to do is track down a lock for the coin door and get my D2K kit, and it's finished (as far as I'm concerned).

Of course, if I ever do remedy the situation- I'll be sure to let everyone know. But until I can come across some cheap extra parts- it's put on hold.

I'm also happy knowing that the monitor are power supply are completely recapped.
 
I know what you mean. I can live with it, but dont get me wrong, it still sucks.

What pots did you adjust to make it go away, was it one of them or would all of them make it go away?

It just returned on my DDK board after re-adjusting the pots on the game PCB.

The only reason I ask this is because the boardset that I really havent seen it on was one I repaired, which included replacing the screen adjustment pots on the game pcb. This shift doesnt really look like it could be caused by those though..

Who knows.. sorry I couldnt help.
 
I know what you mean. I can live with it, but dont get me wrong, it still sucks.

What pots did you adjust to make it go away, was it one of them or would all of them make it go away?

It just returned on my DDK board after re-adjusting the pots on the game PCB.

The only reason I ask this is because the boardset that I really havent seen it on was one I repaired, which included replacing the screen adjustment pots on the game pcb. This shift doesnt really look like it could be caused by those though..

Who knows.. sorry I couldnt help.


It actually goes away easier with the game board PCB's when I adjust the h-pos and v-pos both. Mind you I have replaced both the game PCB 30k pots with 50ks from Bob Roberts.

Also with the exception of the H-hold pot and the monitor volume, all the pots on the monitor are new.
 
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