Calling Dr. Donkey Kong...

YellowDog

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Donor 2011, 2013
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I have been working to restore a Donkey Kong cocktail and I have made great headway. The original boards were dead except for the startup sound. I bought a partially working boardset off eBay and got the game to play with the sound effects but no music.

I pulled the sound ROMs out and they were corroded horribly. There were 3 legs that broke off in the sockets. That helped, but I only got a dull buzzing instead of music. So I pulled the CPU chip next to the ROMs and had 2 more legs corroded off. I replaced that (fortunately I had a spare sound board, Rock On Hoarders!). Powered up and let there be music and sound effects. It was a beautiful thing, until the video acted up.

The pictures below show the story. It seems to randomly flip between correct colors and the bogus ones. When it is good it looks great, when the background goes off, it looks like crap.

I have reseated all of the ribbon cables and pushed down all the socketted chips I can get to.

Any hints on where to start.

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Any help would be appreciated.

Thanks.

ken
 

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I am assuming that it does. It works fine and then randomly the colors go south and it has bars across the screen. Then it works fine again. There are also some black dots on the screen that don't show up in the pictures. The dots are when the backgound goes pink.

ken
 
The inverter board sits on top of the flyback cage. It is not needed, remove it and hook the video up directly to the monitor chassis.

Also verify your +5vdc & -5vdc.
Dok
 
I'll take a look at in the next day or so. The only way to get to it looks like I will have to pull the monitor.

ken
 
I dont think thats a problem with the inverter board but like dave said there is no reason to be passing through it if not needed. I dont think you need to pull the monitor to get to it....

I would start by checking the row of 4 roms on the video board. If the roms verify you might want to take a close look at the sockets. Oh wait, thats a 4 board set. Im not familiar with the 4 bd set but im sure its layed out similar. Look for a row of 4 roms.
 
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Looks exactly like "Bad 3N (2716)" on this site ->
http://www.brasington.org/arcade/tech/dk/

Yeah, I was thinking the same thing...it translates to 5H on the video PCB on the 4-board stack.


Thanks guys. That is an awesome site.

I will take a look and see if the other boardset has a usable ROM. If not, is this ROM version specific or will any MAME ROM set work? I can burn 2716s so as long as I can be sure I am getting the correct version, I can burn a new one.

ken
 
Ken

It might not be a bad ROM. I see you said you pushed down on the socketed chips. Have you tried taking them out and reinserting them. I would try that first specifcally on the chip that the earlier post's mention.

I had a double DK board that did the same thing. It would be good some times and bad others. The power pin on that ROM just wasn't making good contact. I took out the ROM, bent the power pin out a little and then put it back in it has worked fine since.

Murph
 
The ROM version your board has should be dkongo.zip in MAME (that's the original US "Nintendo 1981" with the ladder cheat). The 2716's on the video board should be the same on either set though. I don't think the upgrade that fixed the ladder cheat did anything with the graphics.
 
I doubt the rom is bad other than possibly dirty legs causing a bad connection. I would inspect the legs and the sockets. You mentioned corrosion on part of the board so I would assume this is your problem.
 
The first place to start is to remove the inverter board if it is present.

Reason:
1. It is Free
2. It is a notorious source for video problems
3. IME the picture will look a lot better without it.

:D
 
Next installment.

To sort out some confusion, I have two boardsets. Both the same. The original boardset was dead except for the sound board. The second boardset was purchased on eBay as semi-working (had the graphics issues and a dead sound card). I swapped the sound board off the original onto the ebay set. The music wasn't working, so I swapped the ROMs and CPU off the ebay boards onto the original sound board (now part of the 'frankenstein' working set of boards). The original boards had corrosion (and other) issues. The new set did not have the corrosion issues.

I pulled the 5H ROM (it turned out to be a 2532) off the working set and verified it against the MAME ROMS, it verified 100%. Just in case I burned a spare. Neither one fixed the problem. Just for grins, I pulled the 5H ROM off the old boardset. It left 2 pins and was totally blank when I verified it (I had to solder 2 donor pins on it).

Next when I get some time, I am going to burn a new set of the rest of the ROMs and see if that helps.

The saga continues....

ken
 
It sounds like you're looking at the wrong 5H ROM. The 4-board DK PCB has a 5H on the CPU board and a 5H on the video board. If the brasington site is correct the 5H(CPU) is a 2532 and the 5H(VIDEO) is a 2716.


Mutherf**** Japanese engineers. OK. I'll go look at it again. Tomorrow (or later today, whichever it is now).

Thanks for the heads up.

ken
 
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