Sony STR-DE345 Receiver "channel tuner locked" Questions

...longer holds pre-sets when there is a power outage. There is no battery to replace to hold preset channels. The preset channels are held by a charged capacitor to maintain the nominal voltage level ...

tuner how do i set my radio stations after they have already have been set. Hi Dude Presetting channels for radio stations is generally all the same on most systems. Select the frequency you want and ...

I just picked up a used Onkyo TX-SR502 receiver that has no audio output on any of the channels. I obtained a service manual for it and have tried a few things, but dont know the source of the problem