Chosen Solution

Sony TA-FE910R I dont understand much of the internals of my technical devices, unfortunately. Its getting power and I can turn it on, LED’s are shining from inside and from the power button. Also you can connect other devices t the AC-Power Outlet. But there is no sound output on the speakers anymore. I tried every input channel, different cables and every output speaker channel. All dead output. And diffrent speakers of course Im affraid I damaged it when I, in my stupidity, coneccted a battery powered fary lights to the music output (speakers) adapter/ports. I know, I shouldnt have done that. But im not sure its realy the reasen for it to be dead and I never would understand whats damaged exactely. Thanks for your interest! Havent expected that :) PS: I also checked the boards inside for any burned stuff. But with my untrained eyes I coulnd find any obvious damaged components

=== Update (11/06/2021) === ok I got the multimeter now and watched some youtube videos to get an expert. I would set it like on the photo to measure the 2.2V:

But then… Where do I have to touch the black and red stick of the multimeter? One of them to the 7th pin of CI 401 (photo), but which one? And the second to…?

And I’ll do all this while the amplifire is pluged in and powered on right? Little afraid of that :)

@schniefelix it did get a little later than expected. Anyhow, for now and this is not yet an answer, here is the partial service manual for this model which includes all the schematics. We can only be on the same page if we got the same book :-) The board where the speaker connections and the relays are is the Sp TM board and we’ll have to work our way up from there through CN501 and CN502 Sony TA FE910R SM Looks like one of the relays controls power to the ,main board and the other provides speaker protection. So when you turn your Amp on you should actually here a “click click” when both relays get energized. Since you have lights etc. I would expect at least one click. Let us know what you hear or “feel on those relays. IC401 on the main board is a UPC1237 Amplifier Protection IC which we can check the voltages on according to the schematic. Pin 7 on this should have 2.2V to close the relay for the speaker circuit. If you do not yet have a multimeter and have not tested live circuits you want to let us know so we can provide a bit more guidance on that. Potential touching a component/circuit while it is “hot” could be a shocking experience :-) So no rush and we shall get there eventually.