Sony STR-DB940 no sound

[stoN_Cold]

I was the first owner. No smoke or fire.
Normally on, display on, relay clicks but no sound output. All settings are repeatedly tested.

Suggestions?

 

[JonSnell Electronic]

Check all power amplifiers. One down, all that will happen is the main power relay will switch but not the loudspeaker protection relay.

 

[stoN_Cold]

When I touch my fingers any pin potentiometer volume hear the hum in all speakers.

So all amplifiers are correct