DK - minor sprite sparkles and a ROM question

modessitt

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Been working on a DK 2-bd set today around football. In spite of what I've read online, I could NOT get it to work with a DKjr Video PCB that is known good. I finally got a DK Video board working.

So - the only real issue is that there are some minor sprite sparkles in various places. I usually see a couple that repeat in the barrel stack to the left of DK on the girder screen. Sometimes a couple will pop up in the moving barrels. Sometimes I'll see a little horizontal line pop up over Jumpman's head when he is moving, but not always. There is some type of line or something that pops up from time to time above the girl's head beneath the score that stretches the width of the screen.

I've swapped all the socketed chips out with another set, with no change. I've shot every part on both boards with freeze spray without it going away.

Like I said, it's minor, and not really that noticeable, but I notice it. Anyone have a bright idea?

As for the ROM question - during my troubleshooting, I verified all the ROMs on my ROM burner using ROMident. The two Sound chips 3F and 3H came up as unknown with a different checksum than what MAWS shows, although MAWS shows different locations and checksums, which leads me to believe those are for the 4-brd set. I checked both sets of ROMs that I have and they both came up with the exact same checksums. I can't test the sound at the moment (on my bench), so should I be worried?
 
as outlandish and obvious as this sounds... your roms aren't plastered in a bunch of corrosion, are they? happened on my DK, it would scramble up and freeze up until I got the sandpaper out.

then again, that would be too easy. aren't all those chips windowed? can't you just reprogram them?
 
Look at the original ROMs for corrosion on the inner surface of their legs. The DK boards used single wipe sockets that contact on the inner leg surface.

If you find legs with corrosion then check the matching sockets for corrosion and replace any that are bad. Clean the chip legs before reinsterting into the new sockets.

If that's not it then I'd lean towards a RAM issue with the sparklies happening. Last board I fixed (not a Nintendo) that had sparklies issues ended up having a broken resistor on a /CE line which was affecting the signal to the RAM.

RJ
 
Are you running this with a switcher or an original Nintendo power supply? I stopped using a switcher for my bench set-up because of sprite sparklie issues. I averaged about 50% of my Donkey Kong/Donkey Kong Jr. boards exhibited this issue with a switcher, but were totally fine with an original. It's those damn ECL chips and their demand on the -5 volt rail.

Edward
 
Chips are clean and sockets look good.

I am using a switcher on the bench. I thought about those ECL's and hit them with freeze spray to see if it helped, but it didn't. I have a working DKjr set that shows no problems whatsoever. I have to drive 2 hours to put this in a machine, and don't want to rely on the original PS being the fix.

I just wish these damn Video PCB's would swap and work. The DK and DKjr Video PCB's look exactly alike, but when I swap all the DK chips to the working DKjr Video PCB, it just boots to some garbage on the screen. That's why I spent a bunch of time getting this DK Video PCB up and running. Of course, I have a bunch of DKjr boards, and only a couple DK boards - at least the 2-bd set (I have 3 of the 4-bd sets but I need an edge connector for the cab).

Does this sound like something on the Video PCB or the CPU PCB?

BTW - I should have mentioned that I tried piggy-backing a 2114 on all the CPU and Video RAM (except for the two 2184's) but that didn't do anything...
 
I think you are missing what Elutz said. One of the latest theories is that the -5v on a switcher doesn't have enough current for DK boards.
 
I think you are missing what Elutz said. One of the latest theories is that the -5v on a switcher doesn't have enough current for DK boards.

Easy way to check that. Since it's a switcher, check both for droop (with a DMM), and ripple at switching frequency (several tens of kHz IIRC, need a scope, DMM may not see it) when the board is hooked up and running. If the -5 is overloaded, you'll get droop, or ripple, or both.
 
I agree with all of above posters about the switcher voltages (in general). However, I think this Mike's repair log may offer some insight into your specific issue :

"04/01/2003

Problem: Sparklies on Kong's lower lip when he grins and on the barrels in the top-left section of the first level.

Solution: Bad 73LS163 at 3E on the video board"
 
I think you are missing what Elutz said. One of the latest theories is that the -5v on a switcher doesn't have enough current for DK boards.

Does that apply to DKjr boards as well? I've tried three working Dkjr's PCB's with an issue...
 
I agree with all of above posters about the switcher voltages (in general). However, I think this Mike's repair log may offer some insight into your specific issue :

"04/01/2003

Problem: Sparklies on Kong's lower lip when he grins and on the barrels in the top-left section of the first level.

Solution: Bad 73LS163 at 3E on the video board"

I didn't see that on his site when I looked. I'll check that out. Is this something I'd have to swap out or can I piggyback it?

EDIT - is the 73 correct? It's not supposed to be a 74LS163 is it?
 
I didn't see that on his site when I looked. I'll check that out. Is this something I'd have to swap out or can I piggyback it?

EDIT - is the 73 correct? It's not supposed to be a 74LS163 is it?

I only have a 4-board handy, but I'm seeing a couple of 74LS163AN's, so I assume 74 (plus I don't think a 73 exists). No clue on the piggyback or not.
 
For what it's worth, I too have had a few inexplicable problems with DK not running correctly on a switching power supply. It was completely hit or miss. I kept swapping DK boards until I found one that worked. Both Arcade Shop and Quartercade both said they see problems with running DKs on switching power supplies.
 
I am having similar issues with my Mario.

When I boot the game there is an artifact on the B in the title screen.

When I play for a period of time, the bottom pipe starts flashing and then gets drawn twice on the screen.

I'm pretty sure I have the same issue as you do + a heat issue as things get worse the longer the game is on.
 
Does that apply to DKjr boards as well? I've tried three working Dkjr's PCB's with an issue...

I've had it happen with both titles....and totally random. I chased my tail too many times to count.....so I finally bought a Nintendo power supply for my bench, just for testing/working on Donkey Kong/Donkey Kong Jr. boardsets.

A lot of stuff can cause this issue.....not just a switcher. I just know.....from my experience......it sucks spending tons of time looking for a board problem.......when it's the damn power supply.

The classic era Nintendo boardsets are stuffed with quite a few ECL logic family of chips. These chip's main operating voltage is negative 5 VDC. This puts a heavy drain on the -5VDC rail. Nintendo boards pull damn near 1 amp on the -5VDC rail. Most switchers are rated at 1 amp on the -5VDC line (some, not even that much). Modern switchers are made very cheaply......even if it's rated at 1 amp, doesn't necessarily mean it can handle a 1 amp draw. To make things worse.....as these Nintendo boards age, some are starting to pull even more amps (I'm talking milliamps, but if they supply is already struggling....).

Edward

Edward
 
I agree with all of above posters about the switcher voltages (in general). However, I think this Mike's repair log may offer some insight into your specific issue :

"04/01/2003

Problem: Sparklies on Kong's lower lip when he grins and on the barrels in the top-left section of the first level.

Solution: Bad 73LS163 at 3E on the video board"

Looks to be fixed. I tried piggybacking the 74LS163A at 5E with a new 74LS163, but results were inconclusive, so I removed the chip and installed the new one. Most of the sparkles went away, but there were still a couple left. So I replaced the 74LS163A at 4E with a new one - and the sparkles are all gone...
 
Looks to be fixed. I tried piggybacking the 74LS163A at 5E with a new 74LS163, but results were inconclusive, so I removed the chip and installed the new one. Most of the sparkles went away, but there were still a couple left. So I replaced the 74LS163A at 4E with a new one - and the sparkles are all gone...

That is frickin' wicked, congrats. Thanks for coming back to close up the thread with your results.
 
Looks to be fixed. I tried piggybacking the 74LS163A at 5E with a new 74LS163, but results were inconclusive, so I removed the chip and installed the new one. Most of the sparkles went away, but there were still a couple left. So I replaced the 74LS163A at 4E with a new one - and the sparkles are all gone...

I Just found this thread but I have had 2 boards with that issue and that fixed it for me. I Think that repair tip came from mikes arcade, or at least thats were i found it. glad to hear you got it working.
 
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