dillingerradio
Enthusiast
Hello folks! I could use your help with Donkey Kong Jr. once more, if you've got the time, please!
The Issue:
Donkey Kong Jr. seems to be suffering from frequent, intermittent audio drop-outs, making it sound scratchy/crackly/static-y. I also only intermittently receive the power-on sound.
Example:
I have uploaded a clip of the intro (with sound) that you can hear here: https://imgur.com/38h43GU
You can see a visualization of this issue in the audio spectrogram in the provided image attachments on this post.
Work Done:
I attempted to look up some information in my operator's manual, but it seems the one I was able to find does not accurately describe this board revision (I think, the alphanumeric sectors on the side of the schematic don't match up with mine). I also did some research and found a couple resources that seemed to indicate the chip in spot 7K (just before the DAC) as the culprit in many instances of sound problems; however, when I piggybacked a new LM324 on top of the chip at that spot on my board it did not appear to have an impact. Additionally, I noted my board does not actually have an LM324 at that spot (though I presume the LM324 is a suitable alternative for the chip in place there). I tried a different Nintendo to JAMMA adapter as well, to verify that the audio amp on the adapter I have was not the root cause, and it seemed to have no impact (the audio issue remained). I removed the 8035 sound processor and cleaned it with a fiberglass scratch pen, then flushed the socket with DeoxIT before resocketing. I performed the same maintenance on chip 3H which contains the sound files.
I have two DK Jr. sets here that both have this exact same problem, so I'd love to root out what it is, if anyone can point me in a good direction of something to try next as I'm at a bit of a loss now.
The Issue:
Donkey Kong Jr. seems to be suffering from frequent, intermittent audio drop-outs, making it sound scratchy/crackly/static-y. I also only intermittently receive the power-on sound.
Example:
I have uploaded a clip of the intro (with sound) that you can hear here: https://imgur.com/38h43GU
You can see a visualization of this issue in the audio spectrogram in the provided image attachments on this post.
Work Done:
- Board recapped - no effect.
- New LM324 chip piggybacked on spot 7K - no effect.
- 8035 sound processor removed, cleaned, resocketed - no effect.
- Chip 3H (sound files) removed, cleaned, resocketed - no effect.
- Nintendo to JAMMA adapter swapped for a different design to ensure audio amp not at fault - no effect.
I attempted to look up some information in my operator's manual, but it seems the one I was able to find does not accurately describe this board revision (I think, the alphanumeric sectors on the side of the schematic don't match up with mine). I also did some research and found a couple resources that seemed to indicate the chip in spot 7K (just before the DAC) as the culprit in many instances of sound problems; however, when I piggybacked a new LM324 on top of the chip at that spot on my board it did not appear to have an impact. Additionally, I noted my board does not actually have an LM324 at that spot (though I presume the LM324 is a suitable alternative for the chip in place there). I tried a different Nintendo to JAMMA adapter as well, to verify that the audio amp on the adapter I have was not the root cause, and it seemed to have no impact (the audio issue remained). I removed the 8035 sound processor and cleaned it with a fiberglass scratch pen, then flushed the socket with DeoxIT before resocketing. I performed the same maintenance on chip 3H which contains the sound files.
I have two DK Jr. sets here that both have this exact same problem, so I'd love to root out what it is, if anyone can point me in a good direction of something to try next as I'm at a bit of a loss now.
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