My Sharp LCD TV hums when it is on and even after I turn it off for awhile?

Question

My Sharp LCD tv has a low but loud hum when it is turned on and is much more noticeable at night when everything is quieter. It does not go away when I mute the tv and will still hum for awhile after I turn it off. I hang it on my wall and the one time I took it down to re-hang, it stopped humming for a few days. Any ideas? Please don't advise the obvious like take it to servicing; I just want to know WHY it might be humming like this without committing financially yet. And no, I don't have warranty anymore.

Answer 1

Humming like that is usually coming from the TV's power supply.  The 60 Hz household current is processed by the power supply to make it useable by the TVs circuitry, and the low hum sounds to me like 60-cycle power noise.  Since you were able to get it to stop for a while, I suspect the problem is mechanical: a loose component somewhere in the set that got jiggled around just enough to stop the humming when you moved it.

You might be able to get it to stop by moving or jiggling the set a little, but be cautious - don't go slamming it with your fist.  A permanent solution would probably involve getting the power supply replaced, since most service shops these days don't try to fix problems, just swap out components.