Yeah most games you can control it from the service menu. Also, you can control the volume for a CPS2 through the kickharness. You just have to have the wires in use. See link. Pretty easy for the most part. Even if your button is broken. These two options should still help.
PS: Just remember that you need to use the VOLUME GROUND to both VOL+ and VOL-. I do not know what could happen if you use a standard ground wire. I just know that the pin specifies volume has it's own GROUND.
ok, I got my Volume button the other day and took my CPS2 board. Plugged it in and turned it on and I had lines on the game? I then took it back apart to look at it and put it back together and plugged it in again to test it and everything was fine.
Any buddy know why this happens? I did not do anything diff the 2nd time.