Question about Donkey Kong Jr. "muffled" sound

BigDiceBudha

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Question about Donkey Kong Jr. "muffled" sound

I have a pretty nice Donkey Kong Jr. stand up. Clean, Looks great, plays great, never given me a problem in over a year of ownership. The other day, I flipped it on, and the sound was coming out a little muffled. Almost sounded like sound coming through a blown speaker, although the volume has never been to the level where it would blow the speaker. That's the best I can describe the sound, like muffled or something. Last timed I turned it off, worked fine, turned it back on and off again a couple of times, muffled sound. Any suggestions on where to start, what to look for? Thanks.

I'm mainly a pinball guy and have never worked on an arcade before. I'm very wary of anything having to do with the monitor, for obvious reasons.
 
Pull the Sound CPU out and clean the legs. It's next to your Z80CPU chip I believe it's labeled 8048???
 
If the monitor is a Sanyo 20ez, you can buy a Nintendo audio board repair kit from Bob Roberts.(Look under "cap kits") It replaces caps and transistors on the audio amplifier board and solves a lot of sound problems. The audio amplifier board is a little pcb next to the monitor chassis on the monitor frame. Be sure to plug in the wires in the exact places you removed them from the audio amplifier board in order to avoid having a bad day. They should be labeled with letters. Hope this helps.
 
I'd rebuild that soundboard, cheap, and simple to do....I get mine rebuild kits from Bob.....
 
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