Donkey Kong graphics glitch

BeagleBoy

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Donkey Kong rom graphics glitch

I've finally got my DK board installed in my cabinet, and played it tonight. Everything seems fine except: on the rivets screen, there's a small whitish blob that appears and moves around through the "high score" text. I might have seen it show up at the very bottom of the screen (lined up with the top) as well, but I'm not sure.

When I get a chance, I'll see if I can snap a picture. But I thought I'd throw this out anyway, and see if anyone has any idea of where to troubleshoot.

-Jim
 
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Here's a shot of what I've been seeing. As you can see in my "time lapse" photo, the light-colored blob moves around in the high score text.

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That is whack, Jack

Surely someone has seen something like this before....

Judging by the lack of responses - I don't know if we have ;)

I certainly have not seen nor heard of anything like this. Being a moving object onscreen, I'm inclined to lean towards sprite roms or associated data path. BUT, it's in the damn high score segment, which is a somewhat static object and I don't know which roms contain the high score code, possibly the main game program roms. Having extra roms and boards around to swap parts with might help. Power shortages or fluctuations will cause alot of weird stuff to happen (like flipscreens), but again, this is something in particular I've never seen.

One last possibility is that this is the "sparklies" that are referred to at Mike's Arcade site in the DKJR Repair Log section (these also apply to DK). There is a couple mentions of them between the DK and DKJR sections, and it appears the DKJR section offers the best troubleshoot on them, utilizing compressed air (freeze spray) to cool the chips in question (10124's and the 10125) while powered up. Good luck, and keep us posted as to what transpires.
 
Okay, an important data point. It's the fifth foxfire. It appears when the fifth foxfire spawns, it oscillates back and forth when the fifth one moves, and goes still when the fifth one stops or climbs a ladder. And it disappears if I hit the fifth one with a hammer, and reappears when it respawns.

And yes, it only happens with that specific one. If I clobber any other foxfire, it doesn't get rid of the blob. And looking closer at it, the blob is somewhat foxfire shaped. The top half is at the bottom of the screen, and the lower half is at the top. It appears at the very left of the screen when the foxfire spawns, and moves to the center (and stays there) after the foxfire starts moving.

Unfortunately, I don't have any other TKG4 roms to try swapping. I suppose if I came up with some eproms, I could dig up one of the programmers at work and burn a set (assuming anyone knows where the huge old programmers have been stored).

-Jim
 
Personally, just thinking Logically I don't think it'll be a rom problem, since it's displaying the foxfires correctly. If the foxfire image was messed up, maybe, but since it's showing that and then a mirror up in the top of the image, I think it would have something to do with a ram or something in that area.
 
Surely someone has seen something like this before....

I've got a Crazy Kong board with graphical glitches where you can see part of Mario above the score, but I don't know the solution....oh, and don't call me Shirley :D
 
Personally, just thinking Logically I don't think it'll be a rom problem, since it's displaying the foxfires correctly. If the foxfire image was messed up, maybe, but since it's showing that and then a mirror up in the top of the image, I think it would have something to do with a ram or something in that area.

Yeah, I've thought about that, too. But it only effects the rivets stage. All other levels play fine without any hiccups. But I suppose the rivets stage could be the only stage to hit that section of ram (or hit it in any way that mattered).

-Jim
 
Any other thoughts on this? To recap, on the rivets stage, when the fifth firefox is on screen, a cyan-colored copy is drawn at the very top/bottom of the screen, always in the center or at the very left, regardless of the actual firefox's position.

It's almost like a bitblt routine doing an xor at the wrong spot.

Should I pick up some spare roms, and try swapping them? Is it more likely to be ram?

-Jim
 
I haven't had a chance to swap roms yet, but I did notice one other interesting thing. The glitch is actually an image of Mario, not the foxfire. It's connected to the foxfire as I mentioned above, but the image is mario.

Another interesting point, the exact same glitch happens on some of the new D2K levels: Foundry and Refinery, and during the first intermission.

Hopefully, I can try swapping roms tomorrow.

-Jim
 
I swapped all the roms, and the problem persists.

What's odd is that the same problem shows up on the new screens in DK2. For bad ram, I wouldn't have expected the exact same behavior from completely new screens such as Incinerator. Though, he might be reusing routines from the rivets level.

Hmmm. It looks like if I play DK2 immediately after the game has been sitting off, the glitch doesn't start happening until a number of seconds after I've started playing. I may be trying some freeze spray in the near future.

-Jim
 
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