Marty:Crackling Audio

"All audio is static like and even crackling"
Very common issue. Capacitor near Yamaha IC has spilled. It's the 470uf, 10V capacitor. Replace it and the audio becomes clear. In this board revision, it's C22.



"I have to turn my sound all the way to maximum to hear BGM Audio"
OP-Amp failure in the sound circuit. It isn't capacitors. It's an IC labeled TL084.

After changing the op-amp, burn a copy of Tatsujin Oh and go to the options menu. There is a BGM audio sound test you can use to confirm if the problem is fixed or not.