I have a loud humming in my tv after it has been on for a while

Some surround modes don't use the center channel. This is where most vocal tracks go to.

Hello Sir, Hi, if that is the case, your inverter board is generating audible high frequency noise. the inverter board is true to produce high frequency pulse needed by the LCD, but if should not be audible. try replacing the inverter board and see if the noise will dissapper .

There is an internal switch for record/playback. This commonly fails causing this issue. It will need to be replaced.

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Check speakers for distorted or dead drivers . Disconnect and repair. receiver will blown if not disconnected.

Is the noise audible through the speakers or is it a physical clicking directly from inside the receiver?

If the former, what source(s) do it and are they digital or analog?

It doesn't appear there is a fan so NO physical noises should emanate from the receiver. I'd suspect an arcing component or something electrical. THAT might be dangerous to the receiver or even a fire hazard. Get it looked at.

If you get your system up and running and hear an audible buzz or hum, the first culprit to look at is either the powered subwoofer or your reciever feed at the entry point to your system.

The hum you hear from the speakers and from the unit itself originate with 60hz AC power. They may not actually be related. Sometimes a transformer will hum slightly and unnoticeably. That you're getting a loud speaker hum says there is an electrical leak or a grounding issue somewhere.

Do all sources produce the hum or, say, just the phono? How about on headphones? Try rotating the AC plug. In those days they weren't keyed with one large blade as they are now.

this problem is sif coil & sound releted 5.5 crustal &releted pf try this

It's possible a fan or a hard drive is going bad. When the bearings in those devices start to go out they a start making noises like that.