My sony KV-G21PD1 sounds
Either your TVs internal speaker or its sound output Ic has damaged. You can make sure about which part is damaged through the following sugession.
Just place your ear, very close to the TVs speaker side, and switch on your TV with its front panel power switch, not by the remote control. If you can hear a 'thumb' sound or 'HUM' sound, you can make sure that the speaker is ok. If you hear a 'HUM' sound as describe above, make sure that its sound output Ic has damaged. If the sound output Ic has damaged, sometimes you may not hear any sound at all too.
Connect the TVs audio out RCA scoet to an amplifier, if you have, and try to get the sound through it. If there is sound through an external device, make sure once again that the internal sound output Ic has damaged. Speaker can be checked by a torch cell, connecting its terminals to the two leads of the speaker, with two pieces of wire, just intermittent touch, you can make sure that it is ok or not.
To replace the sound output Ic, you must open your TV, and locate the sound output section inside it. It is easy, to do, just follow the speaker wire, and find it from which point from the main board it orginates. Somewhere near to it, you can loact this Ic.
Before replacing the Ic, just measure whethere there is voltage comes to its supply terminal or not. If there is voltage, and no sound at all, replace the Ic with same type and number without any doubt.
If there is no voltage comes to the input pin of that Ic, check the track leading voltage to that point, and find whether there is any resistor has opend or not. Ok
If you need any further assistance, contact me through Fixya.
on Nov 26, 2010