I have a Sony STR-DN1050 Receiver. It was working fine earlier and I turned it off for a couple of hours whilst I did some other things When I turned it back on again the sound was broken.
I cant work out how to explain it properly but mainly there is no real speech coming out when TV is playing, it is very obvious for anything that is Dolby (ie Sky HD), changing to SD channels gives me speech. It is the same across all HDMI inputs, including ARC.
The test tone page is probably best to show the issues. When I set it to FL or C I get no sound, when I set it to FR I get sound through all the front speakers, when I set it to SL I get no sound set it to SR and both rear speakers produce sound, then when I set it to SW sound comes out the centre speaker.
Now this has been working with no issues for months since it was setup, I have checked all the connections are good and true, I have factory reset it, updated it (as there was an update showing as available) none of which have made a difference.
The auto calibrate feature fails saying not all speakers are being heard, which is true as FR, C, RL produce no sound when targeted directly.
I bought this in a closing down sale so no chance or talking to the retailer about getting it fixed and I have heard Sony are not great when you have no registration/receipt (as I cannot find it).
I can only assume something that controls the audio to the correct speakers has broken.
Not sure anyone will be able to help at all, but thought I would post anyway.
I cant work out how to explain it properly but mainly there is no real speech coming out when TV is playing, it is very obvious for anything that is Dolby (ie Sky HD), changing to SD channels gives me speech. It is the same across all HDMI inputs, including ARC.
The test tone page is probably best to show the issues. When I set it to FL or C I get no sound, when I set it to FR I get sound through all the front speakers, when I set it to SL I get no sound set it to SR and both rear speakers produce sound, then when I set it to SW sound comes out the centre speaker.
Now this has been working with no issues for months since it was setup, I have checked all the connections are good and true, I have factory reset it, updated it (as there was an update showing as available) none of which have made a difference.
The auto calibrate feature fails saying not all speakers are being heard, which is true as FR, C, RL produce no sound when targeted directly.
I bought this in a closing down sale so no chance or talking to the retailer about getting it fixed and I have heard Sony are not great when you have no registration/receipt (as I cannot find it).
I can only assume something that controls the audio to the correct speakers has broken.
Not sure anyone will be able to help at all, but thought I would post anyway.
thankfully back to normal after switching all off and back on 
glad you sussed it though.