No sound is coming out of my tv

SOURCE: NO SOUND

Unplug the power to the tv for couple of minutes; replug and should have sound!

SOURCE: Volume decreasing to zero by itself

Have you looked to see if the Button on the tv itself is stuck in. Press it and you might be able to feel for it sticking. If this is the case you may want to try a baby wipe or something similar to try and sort this out. (dont use a sopping wet cloth)

hope you get this sorted.

Little Dish Fitter.

SOURCE: Hitachi plasma buzzing noise

sounds like bad audio pcb if buzz comes thru
the speakers,

SOURCE: high pitch sound for Sony FD Trinitron WEGA KV-27HS420 27" TV

The high pitch squeal you hear is usually caused by a coil vibrating, normally in the horizontal circuit. I've also seen the ferrite bead on the horizontal output transistor do this, but, it is rare. I normally will repair this by finding the coil and "tightening" it. To tighten a coil, technicians use different chemicals, such as, a hot glue gun, rubber silicone or even finger nail polish. I will find the coil that screams by starting with the usual suspects and using a wooden dowel, barely touch the coil and if the pitch of the noise changes, then, thats the coil that needs repaired. If you do not know your way around the inside of a television, I never recommend you do so, since, this procedure must be done with the set turned on and you poke your hands around the inside of the set by the high voltage circuit. Hope this helps your decision.

SOURCE: rca 32v524t chassis-atc010a

This sounds like something best handled by an experienced tech since the fix involves extreemly high voltages nearby,
If you have a very good knowledge of the inner workings of tv's then ask for more information.