I am new and know nothing.  I have a big Sharp PH-480 from the early 80's.  The speakers are detachable and the left channel has no sound output.  I have tried the balance bar and have tested the speakers using each one plugged in left & right.  Any ideas regarding how to find a repair tech in my area?  I live in Birmingham, AL.  Thanks for any advice.   

Do both Channels work when using headphones? If they do it could simply be a bad joint on the Speaker socket.

Switch cleaner is often a nice easy fix

Allways a good first step!