Connected a radio tuner amplifier to the headphone jack of the TV

Hi @wimcy ,

You may have damaged either the LM4810 IC that feeds the headphones and this is impacting on the audio processor IC or the audio processor IC M SP4550K or both.

Here’s the service manual for the TV which may help.

Here’s an image taken from the manual that shows how the headphones relate to the audio system.

(click on image to enlarge)

There are schematics of the audio system if you wish to get down to board level repairs but if the audio processor IC is damaged as it is a multi pinned IC, it will be not easy to replace. It may be easier to replace the board that it is on.