01-31-2015, 08:22 PM
No, ain't no expert in that.
But before going inside, I would try to (even though I think they are OK) bypass all circuits between MPX unit and control amp by disconnecting everything first from MPX's L/R outputs, and from Con amp IN1 and IN2 inputs and then connecting them respectively L to IN1 and R to IN2.
If it is still low vol, then further exploration into FM circuitry is warranted.
But before going inside, I would try to (even though I think they are OK) bypass all circuits between MPX unit and control amp by disconnecting everything first from MPX's L/R outputs, and from Con amp IN1 and IN2 inputs and then connecting them respectively L to IN1 and R to IN2.
If it is still low vol, then further exploration into FM circuitry is warranted.