Pengo - sound issue

[trickmanterry]

Hello! I am the owner of a vintage Pengo machine. I'm pretty new at
classic arcade ownership, so I only know a few of the ins and outs of
schematics and such, so please bear with my ignorance as I field a
question or two to all of you.

When I first got the machine, I noticed when I turned it on, there
would be a buzzing noise coming out out the speaker. I opened the coin
door and inside was a volume control, and it was all the way down,
which was surprising to me because the music and sfx are pretty loud.
When I turned the volume Up, the buzzing noise faded away, but the
sound ends up being WAAAY too loud. So right now I have to opt for
loud and buzzing, or ear-piercing and no buzzing noise.

Is there a sound setting other than this volume control I can access
to turn it down further? Any help would be greatly appreciated. Thanks!

[jayrowthee]

I believe there is a pot on some of the revisions of the PCBs that can
also have some impact on the sound.