BASH Amp Repair Help (From Klipsch Synergy SUB-12)
I have a BASH amp that needs repair. Not sure if this should go in the class D section or not (BASH class D-ish?
) It comes out of a Klipsch SUB-12. From what I've diagnosed so far, one opamp is bad (easy fix), and some part of the digital converter/drain voltage modulator. It appears that both sets of output transistor pairs (IRFZ14 and IRF9Z14) are OK (tested with DMM, verified gate signal looks OK on oscilloscope). The FET that controls the drain voltage (IRF530) seems to test OK, but without the digital converter working correctly I can't be 100%. One part certainly seems to be missing, (R61) which is a series resistor going to the current sense line. The UC2842A VCC line only goes to 2V when it is installed, but without will go to 22V. I had tried multiple UC2842A chips, and all do the same thing so I assume that isn't the problem. Solving both of these problems seems to be first on the list to getting this amp up and going. I can't really identify where the +22V is sourced from either. One pin on the module goes from a cap to ground and that's the only trace I can see connected to the main PCB.
Does anybody have a schematic (long shot) or at least have a high quality picture of the board so I can identify a missing part vs a DNI? Any help or guidance on this amp would be helpful.