Audio Systems: Audio sound, fisher stereo, bench test

Question
I have a model 404 Fisher stereo receiver. I am only getting sound output on the left rear channel. I also hear a humming noise in both speakers.

Answer
Dear Martin,

The Fisher 404 is actually a vintage quadrophonic receiver, made circa 1975. This unit is so old that channel failure, in your case three of the four channels, could be caused by any number of things: accumulated dirt/dust inside, power amplifier failure, preamplifier signal loss, and so on. Ditto the hum--anything from a loose grounding wire to again dust and dirt.

First, I'd open it up and clean it. Although a good cleaning may or may not restore the channels, but it will save money if you decide to take the unit in to have it tested and/or repaired. A good amount of repair time for old stuff is spent on cleaning.

However, I don't think you have any choice but to take the unit to a qualified repair service for a diagnostic and bench test.

Kindest regards,

Kevin