MVS sound problems

I have a MVS Neo-Geo system. I recently bought both SVC Chaos and Magic Drop 3 (both kick ass games). But sometimes when I play, the sound seems to go in and out, sometimes it's just right, sometimes too loud, sometimes too quiet. Since it does this with more than one cart, I assume it's my MVS that is the problem, not the carts. So, what should I do to try and fix my Neo-Geo??? Any suggestions?

Is this a Cab or Supergun set-up...?

How many slots..?

As always I suggest giving everything a good cleaning..the carts,connectors,Mobo Connectors,Jamma edge and Harness-pins.

IMO your Harness pins may be loose and not making a good contact..
Just how loose does it slide on the edge connector.?

Or the slide button on the mother board is dusty,dirty and not making a good contact...(sliding it back and firth blowing it out may fix that problem..

If you are using the big 1 slot MV1..Check the Mono to Stereo switch on the board as I've noticed it can cause this problem..

The 12v in your power supply may be failing..you'll need to take a voltage reading of that from the rail to see if you get a dip in 12V voltage ..