I have two TVs with the same problem.
Sharp lc32le343 = lc32le340 mb.17mb70-5
the problem is the following: the sound is heard at times, but even when the volume is lowered, a continuous noise is heard. same problem in headphones.
watching the optical output turns on and off at the same rate.
tested also with hdmi and scart input.
and as if there were a clock, I tried to check the various voltages and to filter them.
replaced ic audio, and the four 1 uf capacitors near the audio ic.
Also tested sw update.
one of the two leaving it on after one hour works, but as soon as it turns off and comes back on, the problem starts again.
the defect is as if it were muting. The defect is before the audio end because by controlling with an external amplifier you can already hear before the TV switch, scart, hdmi etc.
Thanks for the reply .
if you refer to the 4 conds from 1uf near the TPA3110, I have already replaced them as I wrote.
The tpa3110 audio circuit works well by inserting another signal at its input.
Tell me if you were referring to this or the u3 CXA3813N line-out-amp-stage.