Sound buzzes on Playchoice 10

[ncflagg]

I can connect both monitors up to both speakers with seperate volume controls and they both sound the same. Low buzzing. Not very audible with the sound at a decent volume but it sits there buzzing all the time when I'm not playing it. Ideas?

[Pac-Fan]

A lot of people will suggest getting cap/transistor kits from Bob Roberts and rebuilding the 2 audio amp boards, but I've found that doesn't help anything, unless you were not getting any sound to begin with.

Speaker humm is unfortunately a side effect of the design of Nintendo games.  You can take out the built in amps and provide your own (like out of powered computer speakers or use a Bally/Midway dual sound amp board out of an MCR based game).

Otherwise, besides just living with it, you can also throw on an electrolytic capacitor across the two speaker terminals. Experiment with values to see what works best at the frequency you want to remove--it will help reduce the humm, but also will tend to cut down the high frequency range at the same time depending on the uF rating of the cap.

[MaximRecoil]

I can connect both monitors up to both speakers with seperate volume controls and they both sound the same. Low buzzing. Not very audible with the sound at a decent volume but it sits there buzzing all the time when I'm not playing it. Ideas?

They pretty much all do that, and Punch-Out machines like you have, do it twice as loud as other Nintendo machines, for obvious reasons. Search RGVAC, or this forum, or KLOV forums, or whatever, for "Nintendo hum" or "Nintendo buzz"—you'll find plenty of complaints about this regarding Nintendo cabinets.

The rebuild kits for the Nintendo audio amps don't help in my experience (like Pac-Fan said). And he is correct that using different amps will fix the problem. There are many options for different amps, including: certain car audio amps, PC speaker amps, the "T-amp", the combination Nintendo audio amp/video inverters that Mike from Mike's Arcade sells (link), etc.