Maybe someone else can help. I need some reference point to start. I have no clue what pin 5 on j8 is.
The audio signal comes in the main board through pin3 of connecter and goes straight to pin5 of tl072 (U20). Then from pin7 passes through small ceramic cap goes to other side of U20 and then from pin1 of U20 goes to driver card.
This sounds like U2C on the SLA1500 diagram. It may not be the exact same package but it's doing the same thing.
Do you know for a fact that you can touch the equivalent pins on other amps of the same type without causing problems?
Audio isn't likely to be coupled through a small ceramic cap, especially for a bass amp. Are you sure that you're following the circuit correctly?
Do you know for a fact that you can touch the equivalent pins on other amps of the same type without causing problems?
Audio isn't likely to be coupled through a small ceramic cap, especially for a bass amp. Are you sure that you're following the circuit correctly?