MIMF

I have a partially working Acoustasonic 90 that I am having a difficult time finding information about. It has no volume or noise from either of the channel inputs, but the aux input on the back works fine. I have cleaned and re-seated the ribbon cables connecting the circuit boards together and done a visual inspection without finding any obviously bad parts or bad/broken solder joints. I think I could narrow down the search dramatically with a proper schematic, but I can't find one anywhere. Any help would be appreciated. Thanks!

manualslib.com has a acoustisonic jr on-line.
I was hesitant to link directly.

I don't have a schematic either, but I might suspect either no power going to the preamp circuit board associated with the front panel controls; or perhaps a onetime overvolt condition to that board which baked the op amps.
Time for the meter.