I have had a few CPS3 systems and noticed they all have some sorta sound issue. I just gota 3rd strike system and the sound pot doesn’t work right. I have to turn it all the way up to get the sound on and its very quiet… Must be the age of the boards? Is there a resistor or chip to fix this?
Yes I know it has both options, but have you explicitly set sound to be output as amplified mono from the test menu? An easy thing to miss if using Jap software…!
Regardless of what you set the board to will continue to output mono sound through the jamma connector. I would say that the pot is just going bad, it happens. If your feeling really adventurous you could give changing the pot a try. Youll need to put a multimeter on one of your boards to find out the pots value and measure the pin spacing on the pot to find a match. Could be an interesting project. If you do it let me know how it turns out.