I had the same problem, I realized it was due to bad solder joints in the relays that physically turn the signal on and off to the speakers. There are relays for each speaker and a main relay for the mute/headphone. The click you hear is the relay disengaging. the relays look like narrow boxes about an inch high. If you open up the amplifier, try gently pushing on the top of the relays, if they click you know you have a bad solder joint. Remove the board, turn it upside down and re-solder the relays.
the following video shows what a relay is, and another problem can be that it is dirty, if so follow the instructions in the video to clean it.
Hi! Check page 19 and forward in the manual https://docs.sony.com/release/strde945.pdf It explains what parameters to set depending on your speakers. I cannot answer directly because I dont' know the speakers :) On page 22 there is a good procedure for adjusting the speaker volume using the test tone. Good luck and let me know if it helps!
unfortunately, electronics go obsolete very quickly, and the cost to repair a specific unit is so close to that of purchasing a new replacement that very few places stock parts or do repairs these days.
Unless electronics repair is a passion or hobby of yours, you will spend much time and effort trying to get parts, time trying to replace the defective parts (a waste of time and money if you aren't absolutely certain which parts are bad).
Since the complete board is no longer available, troubleshoot to the compnent level and replace the individual items on the defective board, or just get a new receiver.
I was able to fix this issue by opening up the receiver, removing the circuit board that the power button and speaker selector knob contact, and then reseating that board back onto the circuit board it was connected to (the one with the majority of the control buttons). This completely resolved the problem. The power button works again and the audio does not drop out anymore.
You'll need to perform some further troubleshooting.
1. Try plugging the lead into another input
2. Try another audio player (MP3 player on phone perhaps)
3. Try an alternative lead.
There isn't a simple answer - you just need to perform these tests - then I'm sure the cause will become clear.
Happened across this forum looking for some remote info. Had a similar problem with my 945...main speaker outputs started to click off & on, no rhyme or reason. Found that the solder joints on the speaker output relays were cold (poor soldering). Actually happend twice, two different relays. Took me a while to find it, reflowed the solder, that solved the problem, over two years ago now. Are you able to dig into the receiver? Do you have a (good) soldering iron and some solder? If not take it to elec. shop and tell them to look for cold joints on the relays.
These unit had a habit of getting broken solder connections between the board that the speaker switch and power button are on and the display board. Would have to repair these bad connections for unit to work right. Pretty easy soldering job if you have any experience.