Whine in home audio

[kevin cam]

Hello,I have cheap & old theatre system I use in my
garage the main unit has 10" sub built-in & 5 small speakers with multiple device input options.
Plugged in to 110 & no speakers hooked up and no audio inputs plugged into it there is a whine heard either through woofer or something internal. I have a very long background in automotive electronics and onboard diagnostic systems, I can fix or identify
almost any problem in 12 V systems, but know nothing about the internal workings of audio equipment & what causes
them to produce unwanted noises, can someone help, it gets worse the longer it's plugged into the wall outlet doesn't
matter what outlet or where

 

[americanaudiophile]

Unless the unit doesn't like to be on with no source connected (unlikely) I would guess that the sub amp is oscillating. Connect the other speakers and if you can hear the same thing through them them then maybe there is a power supply problem. You could take a shot at repairing it but it doesn't sound like an expensive unit and give the age it might make more sense to replace it.

 

[kevin cam]

Thanks for your reply, I figured it was gonna be a throw it away thing to get rid of the noise,
but thought I would ask someone if there was an easy cheap fix that I didn't know about.
Thanks again