I apologize if this is posted in the wrong forum, I’m new to Audiokarma. I have been an old tube audio tech for about 20 years, radios from the 30’s & 40’s, early television, tube guitar amps, etc. My nephew wanted me to work on his Sony STR-DA4300ES so I told him to bring it on over. Originally this receiver was in “Protect” mode and wouldn’t even power up. I traced down a shorted power transistor and replaced that push-pull pair along with an emitter resistor and small coupling cap. After that repair, the receiver will power up and seems to be working except I get no sound output at all. I checked the bias and it is perfect, there is no DC on any of the speaker terminals. I connected a set of known working speakers to every speaker output jack and I get no sound anywhere. I plugged in a set of headphones and still nothing. This receiver is pretty complicated compared to the things I am used to working on, in addition it has a very thick operating manual with lots of settings and options for sound output. I went through each menu hoping it was just a setting that had muted the speakers…… I found nothing. I tried to do a factory reset but the receiver comes up with an error code of F:33 which the manual says the receiver does not see speakers connected. I’m not extremely experienced at working on these types of receivers. Can anyone give me a hint as to where to go next? I would appreciate some help from someone more experienced with these newer receivers. Thank you!