let's see, as you say the audio amplifier is fine, it is understood that the audio signal reaches the final integrated and amplifies it without problems ... right? the tensions are fine right? ..... you have changed the eprom and it remains the same .... because the problem you have in the micro ... I remember that elbe tv, they carried a mike that gave that fault, and possibly whatever happens to you ... look in the mic for the pin with the mute and check that line ... if it's ok, change it directly keep in mind that everything is processed in the micro, and then stored in a memory, any parameter related to audio that fails in the micro ... will give you the problem ..... I leave the base that amplifier so much, as loudspeakers, as a signal .... ok .... I hope it helps you