Donkey Kong 3 PCB Problem

MrD

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I just picked up a Donkey Kong 3 PCB. I'm am trying to switch it into a Donkey Kong Jr Cocktail game. Both games use the same edge connector and are supposed to be interchangeable.

The machine/monitor work fine with the DKJR. Just did a recap and all is well.

When I put in the DK3, I get the attached. No sound. Just 0s

I've cleaned the edge connectors. I've removed and reseated all the chips that I could. It makes no difference. There doesn't appear to be any issues that I can visibly see on the boards.

Anyone have any guidance for my next steps?
 

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Didn't specifically say so when I bought it but I got it cheap. Was supposed to have been good when it was pulled, but that was years ago from the sounds of it.
 
I tried that too with the two ribbon cables on the bottom, and the rainbow connector. No difference.
 
I've cleaned the edge connectors. I've removed and reseated all the chips that I could. It makes no difference. There doesn't appear to be any issues that I can visibly see on the boards.

Anyone have any guidance for my next steps?

Actually that picture looks relatively 'right'... unless they pulled some real goofiness with the background color map prom, the colors there match the greenhouse, so you've just got bad BG tile rams and/or bad connections to the character proms.
 
I've tried to reseat the z80. Doesn't seem to make a difference.

Could be like you said, bad character RAMs, but if they were bad, would it still play? No sound, can't add a credit. Definitely doesn't play.

I'll try and reclean everything and reseat.
 
Well I know at least the z80 works. I swapped it with the one on my DKJR, and it works there. So that isn't it. At least not the chip itself.

The other thing that I noticed tonight is, when I first turn it on, if the monitor is warm, I get what looks like random character parts on the screen, maybe less than a sec. Then the coin counter clicks once, and then I get the image above.
 
Well I took and and recleaned every socketed chip that I could last night and no difference. I don't think I can get them any cleaner.

So I thought maybe I could use MAME to debug and alter each ROM file to appear bad, much like this: http://www.brasington.org/arcade/tech/dkj/

I got varying results, none of which seemed like my problem.

What I did realize, however, is that the screen that I get in the OP, isn't a "bad" screen. It's actually the initial screen when it starts up. MAME shows the same screen. So mine is getting "stuck" at that point.

I looked back over my board, and I did find a potential problem at 2E. It's a MB7074 ECL-RAM. It's supposed to have a heat sink but it is missing.

So without really understanding it all, my next "guess" is that the heat sink fell off at some point, and the chip went bad. What I'm seeing is the board zeroing out the RAM, and then locking up.

I think this is available at Mikesarcade. Before I order it, does this seem like a reasonable possiblity? I don't really have any way to test the existing chip, if it's even possible. But the missing heat sink is suspect.

Any thoughts?
 
I think every tendo pcb I've seen has had a missing heatsink or two. Instead of trying to shotgun parts I'd personally contact Dick Millikan and see how much he'd charge you to swap board sets.
 
Maybe I missed it but what are your voltage readings ? I've ran into more than one Nintendo board that likes a little more than 5v to run.
 
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