dillingerradio
Professional
This issue is resolved. The problem was my capture card, the El Gato HD60X, and not my game.
The Issue:
Donkey Kong Jr. seems to be suffering from frequent, intermittent audio drop-outs, making it sound scratchy/crackly/static-y.
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 am new to electronics. Part of the reason why I got into this hobby was to learn, so when responding, please do bear in mind that you're speaking to an amateur at best.
The issue is as previously described (and demonstrated visually in the spectrogram image attached to this post): Audio frequently, briefly, cuts out. This causes the audio to sound bad. Insofar as the music and sound effects are concerned, they seem to play correctly, it's just cutting out. On one board, an additional problem is present in that the boot sound effect only plays intermittently.
Bearing that in mind, it seems the chip on spot 7K--an "MB3614 8217 M11" on my board, which is a quad op-amp that is functionally equivalent to an LM324--is often the source of audio troubles. From the resources I found, it was suggested to replace this with an LM324 chip. So, I piggy backed an LM324 on this spot (rather than fully replacing, for ease of troubleshooting purposes), and it yielded no improvement.
I then removed and cleaned the MBL8035N 8216 C55 audio CPU (commonly shortened to "8035") in spot 7H. I cleaned the pins with a fiberglass scratch pen, and flushed the socket with DeoxIT fluid before resocketing it. This yielded no improvement.
I then removed the chip at spot 3H (which contains the audio data) on the board, cleaning the pins with a fiberglass scratch pen, and flushing the socket with DeoxIT fluid before resocketing. As with the audio CPU, this yielded no improvement.
I then thought that it may be a result of the amp circuit on the Nintendo-to-JAMMA edge adapter I was using. To rule that out, I purchased a different one which utilizes a different setup. This did not yield an improvement, and the same audio issue was present.
I have also completed a recap of the electrolytic capacitors on the board, as part of routine preventative maintenance that I intended to complete anyways. This, too, yielded no improvement.
From the resources I was able to find, it seems the DAC08 is quite resilient, and not typically associated with audio issues. Despite that, I went ahead and replaced it, which yielded no improvement.
I upgraded the power supply to a more robust model (from the RT-85A to the RT-125A), which yielded no improvement.
I reflowed a number of the chips on the board, which yielded no improvement.
At this point, after some discussion- much of which surrounded just how unlikely it was that two copies of the game would have the same exact problem, I went back to the basics. I popped some headphones into my HAS unit to test audio at the edge. It worked perfectly. I then tested it at my OSSC Pro, and again, it worked perfectly. The culprit, as it turns out, was my capture card: the El Gato HD60X.
I have a memory of having checked these audio sources at the very beginning of my troubleshooting; however, it dawns on me that while I maybe had thought to do that, it's possible I did not, and my brain converted the idea into a memory (giving me a false impression) that I then ran with, since I was mired in trying to troubleshoot the board at that point. I also did not suspect the capture card at all, because up to this point it's worked flawlessly for me with pretty much my entire arcade collection (nearly 50 games).
So, I suppose the lesson for this one goes: Before you start in at a problem at all, even if you just checked the very basics, do it again. Be sure, not pretty sure.
Needless to say, while frustrating, this has been a fantastic learning opportunity.. And I've got a very well maintained DK Jr. board now from all the work I did to it.
The Issue:
Donkey Kong Jr. seems to be suffering from frequent, intermittent audio drop-outs, making it sound scratchy/crackly/static-y.
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.
- LM324 in spot 7K replaced - no effect.
- DAC08 replaced - no effect.
- 8035 sound processor removed, cleaned, resocketed - no effect.
- Chip 3H (sound files) removed, cleaned, resocketed - no effect.
- Power supply swapped from RT-85A to RT-125A - no effect.
- Nintendo to JAMMA adapter swapped for a different design to ensure audio amp not at fault - no effect.
- Reflowed numerous chips (3F, 3H, 7K, 8K, 8035 CHIP, CRYSTAL OSCILLATOR, etc.)
- N/A.
I am new to electronics. Part of the reason why I got into this hobby was to learn, so when responding, please do bear in mind that you're speaking to an amateur at best.
The issue is as previously described (and demonstrated visually in the spectrogram image attached to this post): Audio frequently, briefly, cuts out. This causes the audio to sound bad. Insofar as the music and sound effects are concerned, they seem to play correctly, it's just cutting out. On one board, an additional problem is present in that the boot sound effect only plays intermittently.
Bearing that in mind, it seems the chip on spot 7K--an "MB3614 8217 M11" on my board, which is a quad op-amp that is functionally equivalent to an LM324--is often the source of audio troubles. From the resources I found, it was suggested to replace this with an LM324 chip. So, I piggy backed an LM324 on this spot (rather than fully replacing, for ease of troubleshooting purposes), and it yielded no improvement.
I then removed and cleaned the MBL8035N 8216 C55 audio CPU (commonly shortened to "8035") in spot 7H. I cleaned the pins with a fiberglass scratch pen, and flushed the socket with DeoxIT fluid before resocketing it. This yielded no improvement.
I then removed the chip at spot 3H (which contains the audio data) on the board, cleaning the pins with a fiberglass scratch pen, and flushing the socket with DeoxIT fluid before resocketing. As with the audio CPU, this yielded no improvement.
I then thought that it may be a result of the amp circuit on the Nintendo-to-JAMMA edge adapter I was using. To rule that out, I purchased a different one which utilizes a different setup. This did not yield an improvement, and the same audio issue was present.
I have also completed a recap of the electrolytic capacitors on the board, as part of routine preventative maintenance that I intended to complete anyways. This, too, yielded no improvement.
From the resources I was able to find, it seems the DAC08 is quite resilient, and not typically associated with audio issues. Despite that, I went ahead and replaced it, which yielded no improvement.
I upgraded the power supply to a more robust model (from the RT-85A to the RT-125A), which yielded no improvement.
I reflowed a number of the chips on the board, which yielded no improvement.
At this point, after some discussion- much of which surrounded just how unlikely it was that two copies of the game would have the same exact problem, I went back to the basics. I popped some headphones into my HAS unit to test audio at the edge. It worked perfectly. I then tested it at my OSSC Pro, and again, it worked perfectly. The culprit, as it turns out, was my capture card: the El Gato HD60X.
I have a memory of having checked these audio sources at the very beginning of my troubleshooting; however, it dawns on me that while I maybe had thought to do that, it's possible I did not, and my brain converted the idea into a memory (giving me a false impression) that I then ran with, since I was mired in trying to troubleshoot the board at that point. I also did not suspect the capture card at all, because up to this point it's worked flawlessly for me with pretty much my entire arcade collection (nearly 50 games).
So, I suppose the lesson for this one goes: Before you start in at a problem at all, even if you just checked the very basics, do it again. Be sure, not pretty sure.
Needless to say, while frustrating, this has been a fantastic learning opportunity.. And I've got a very well maintained DK Jr. board now from all the work I did to it.
Attachments
Last edited: