On Tuesday, January 15, 2013 10:45:36 AM UTC-5, N_Cook wrote:
j wrote in message ... I'm trying to troubleshoot a 1980'2 era Nak receiver that has pushbutton input switching via a microprocessor (can also be remote controlled). The button lights don't work, and I get no input connections at all. Strange, but the micro works, controlling the volume up and down. Also, the amp works via the pre-out and power-in jumpers. Apparently, some aspect of the switching (done via an analog switch IC) is screwed up. Anyone have ideas on how to troubleshoot this? What ident is the big an.. sw. ?

There should be a switching IC (LCxx22 or TC9163) located on the board. In many cases this is the problem. You will see the signal entering the IC, but no output. I believe that the light and the audio are controlled by the same line. The few of these I have seen in the past were quick fixes by replacing the switching IC. (IIRC)

Dan