20 Most Recent Sony STR-DE635 Receiver Questions & Answers

Might be a bad speaker relay.

It's probably not the switch. These models have a common problem with the solder connections between the switch pcb and display pcb going bad. You need to resolder these connections, and your problem should be solved.

Maybe the Preamp driver IC, looks like a car audio ic on the main board.Often with age the heat generated by the ic will destroy the solder.Makes it look like lava rock in bar-b-que grill. Whichcauses an open circuit in the preamp driver to the audio powerstage.Simply resolder them, most often restores audio. Should havea bottom removalble cover.If not, a fuse normally blows if ic or channel is shorted. Check ifdisplay will say Power off, Protect, etc. That means there is a problem with a channel. Most Sony receivers use darlington transistors, they short easily !! I am an old school component level service tech, I think I do have a schematic for this model and many others.

Nope, power supply it would not even power up.  The capacitors are fried

The most common problem found on FixYa for Audio Video Receiver's is:

My receiver say's "Protect" or turns on then off. What's wrong? Seven times out of ten it is a shorted speaker or speaker wire. To determine your exact problem, the first step is to disconnect all speaker wires "at your receiver" Next: Turn the receiver back on. If your receiver still says "protect" or turns off, it needs to be serviced. If your receiver stays on; reconnect your speakers one at a time and power back up after each speaker. You may find that after reconnecting all speaker wires it works! Most commonly the small braids of wire from the + to the - have touched and have caused the problem. In some instances, you noticed the problem only when turning the volume up. either way, make sure the exposed wires to your receiver are no longer than 1/2" long and are completely under the screw down terminal or slide in. When you've found the wire or speaker with the problem, your receiver will go back into "protect" At this point, disconnect the wire from the speaker at the speaker that may be causing the problem then test again.* Note* Make sure speaker wires do Not touch each other as this Will cause a short! If you turn the receiver back on and it stays on, you now know the problem is in your speaker itself. To test your speaker, you will need a multimeter. Set it to ohms resistance and touch the speaker terminals, if there is a short internally the meter will read "1......" If it's an analog meter, it will peg to the right. There's your problem. Now, within any speaker there are quite a few possibilities as to what could be causing the problem. Most common is a blown coil and the speaker needs to be replaced. Some speakers have internal crossovers (usually floor standing speakers) and may have a shorted or burnt board (usually very visible brown burn marks on the board) and can possibly be repaired if your handy with a soldering iron. Now, if you disconnect the speaker wire at the speaker and it still says "protect" Check your wire for the obvious cut or nail thru the wire if possible. If your system has wiring that runs behind walls, you may need to use your meter again. Disconnect the wire at both ends, keep the ends separated, put your meter on ohms resistance and touch probes to the + and - wires at one side. If the meter pegs to the right or reads "1...." the wire is shorted and needs to be replaced or repaired at the short. Hope this helps.

you need to change audio amplifiers IC´s

Shorted power supply/module is most likely problem.

first turn the actual volume up on that channel on the reciver then make sure your speaker wires in the rear are using the same lenght each