Audio Systems: onkyo txds575 no sound, temperature sensing devices, output transistors

Question
i have owned the abovemodel for years. now it turns on the headphones have faint sound but no sound from the speakers. sometimes after unit is on for 30 minutes it willthen let sound out of the speakers-checks the swithces for aand b stereo and they move up and down opeing andclosing the cirsuoit-when switched they make aclick sound.

any answers

Answer
This sounds like a problem in either the power supply and/or the audio output section.

Here is what happens when an audio amplifier gets old:  The output transistors (and sometimes one in the power supply that is used for voltage regulation) get very warm and the heat grease applied at the factory between the case of the transistor and the heatsink dries out and the thermal transfer gets so poor the transistor get too hot and then either the transistors burn out or the temperature sensing devices shut off the power supply to protect them.

It will take a few voltage checks and temperature checks on the transistors to know for sure.  Cost of repair could be under $100 - or over.  Depends on the failure(s) that are foung.

Onkyo is good stuff. But, this unit is very old and you will have to decide if it is worthy of a repair investment.

Hope this helps.
C
PS:  And, I think, also, as I review your conditions, it could be the result of a bad speaker or shorted wiring.  If you disconnect all speakers at the back of the amp, then connect only one and try, then disconnect and try another, etc. you might find something from the external conditions that could be the instigator. Let me know.