My brother has a Technics receiver model SA-R277 from the mid-80's.
It no longer delivers any sound from left A or left B speaker outputs.
I've tried swapping speakers and wires with same result. no output from left A or left B. I'm guessing the failure might be at the volume control, since one failure there would seem to cause both of the observed failures.
Does anyone have a circuit diagram for this unit? Without one, any advice on further troubleshooting?