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Philadelphia

I've had a pro-sound modded NES for nearly a decade now, never any issues (aside from common 72-pin connector stuff all NES systems suffer from) but recently, the audio output went...well, it didn't go away completely, but it's not making the same 'hum' it usually does.

It first happened when I was working on a track with a lot going on and some notes got stuck. As per usual, I powered the system off and on again but when the sound came through the speakers after powering on, the hum was different and despite MIDI data being sent via MidiNES, no sound was generated.

It's hard to describe but where the regular hum has both high and low end, the new hum has just low end. I tried everything from unplugging the power and plugging it back in, taking the cart out and putting it back in, banging on the sides (pretty much all of the tricks we used back in the day to get games working) but the problem doesn't seem to be with the cart.

It also randomly started working again a few days ago, until some notes got stuck (again) and it went back to the new hum after powering it back up. What's also odd is that when it started working again, I had been powering it on every few hours to see if it would work and although the normal hum hadn't come back, I tried sending MIDI data to the cart and it started working again (and once I paused the track, I could hear the new hum).

I have no idea what could cause this problem as the stuck notes are still coming through until I power off (ie if it was a blown capacitor or something along those lines, the sound should have cut out all together then, and shouldn't have randomly started working again). Although, I do think it's a hardware issue with the NES itself. I can open it up to check it out but if anyone else has any clue as to what the problem could be, more specifically, I'll know what to look for.

I didn't mod it myself, hence I have no idea what the problem could be...

Last edited by Doctor Octoroc (May 9, 2019 9:35 pm)

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If lines 1 & 2 were decoupled properly using 1uF electrolytic capacitors, then the caps could have gone bad.  Pop the lid and take some pics, if you don't mind  big_smile

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Philadelphia
DSC wrote:

If lines 1 & 2 were decoupled properly using 1uF electrolytic capacitors, then the caps could have gone bad.  Pop the lid and take some pics, if you don't mind  big_smile

Thanks for the response! I'll try to take some pictures tomorrow to post here so you can take a look.

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Philadelphia

Okay, not sure what I'm looking for - everything looks good to me but I might be missing something. I only snapped pics of the capacitors and resisters and the board with the audio connection. Oddly enough, once I put everything back together, it worked fine. then 2 minutes into a track I was playing on it, it started crackling like crazy - almost like bit crush. That is a new one!

Any ideas?

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I believe Kitsch sold these mod boards.  I remember picking one up.  Yes, it has the decoupling electrolytic caps.
To do an easy test you can take any audio source and put the wires on either side of the soldered cap wires.  You should have
audio signal coming through.  If not, then the cap has gone 'open'/BAD.  If you have audio, then check with a meter and
confirm the OP-Amp IC is getting power.  After that you might want to check in with Kitsch.  Hope that helps.

Last edited by DSC (May 12, 2019 1:03 am)

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Philadelphia
DSC wrote:

I believe Kitsch sold these mod boards.  I remember picking one up.  Yes, it has the decoupling electrolytic caps.
To do an easy test you can take any audio source and put the wires on either side of the soldered cap wires.  You should have
audio signal coming through.  If not, then the cap has gone 'open'/BAD.  If you have audio, then check with a meter and
confirm the OP-Amp IC is getting power.  After that you might want to check in with Kitsch.  Hope that helps.

Not gonna lie, I have no idea what half of the things you said mean lol. I think I'll just look into pro-sound modding another NES since this one has put in the time and deserves to finally rest haha. Low-gain originally did mine so I'll probably reach out to him to see if he's still in the game.

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Philadelphia

And it started working again...only to crap out after 5 minutes. This leads me to believe it's a relatively easy fix - a loose wire or bad connection. Keeping my fingers crossed!

I'm going to open it up and examine more closely, I can solder joints if need be - but if any one familiar with a pro-sound modded NES with a Kitsch board can point me in the right direction as to where the audio connections are, it would help me a lot to locate the issue. Otherwise I'm flying blind...