Diagnostic for mainboard of Samsung TV LN32A330J1D

I have an old Samsung TV, model LN32A330J1D.

Suddenly, the HDMI in stopped working, altogether with the composite video. Tried with several devices, and the TV just don't get the signal, like if nothing were connected there.

However, the coaxial in for areal anthenna works fine. I still can watch free TV using an anthena.

I wonder if with these symptomps the problem will likekly by corrected by replacing the mainboard, or wil be the fault in another board.

Thanks in advance,

Thank you very much. I have read the manual already. But the symptoms described in the flowcharts doesn't exactly match any of my TV's symptoms.

In the manual it's always mentioned "audio is normal", which is not happening in my TV.

The symptoms here are:

I don't get video nor audio, in either HDMI or composite. I don't get the "no signal" message... it behaves like if it does get signal, but nothing is displayed.