Sony TA-F55

Hi everyone, I have a problem with switching power supply of a Sony TA-F55.

I have changed the electrolytic capacitors, but I don't have output voltage.

300 volt input is ok.

I also try without load, but I don't have output voltage again.

Transistors are ok, and also diodes.

I searched for the service manual or electric diagram and also in the forum without success.

Anyone can help me, please?

Thanks in advance.

Bye
Massi