Onkyo TX-SR705- No Sound

[ykilde]

I've got a Onkyo TX-SR705 receiver and there is no sound output to any of the speakers even after trying all the inputs. I have already done several resets to the unit by holding the DVD + Standby buttons with no success.

This leads me to believe the output transistors are shot and they are on the main board which is on the bottom. I'm a little confused to which one are the output transistors. There is a large heatsink that towards the front of the receive (by the display) which I circled in red and another set on a smaller heatsink towards the rear of the receiver (circled in blue)

Honestly, I really don't know what I'm doing. I tested the transistors on the large heatsink using the diode test function, and I believe some of them are shorted because they are showing voltage both ways at the Collector and Emitter but the tests were done in circuit. I think I need to remove them to test them but I'm not really sure.

Any help would be appreciated. Thanks

[mxslick]

Re: Onkyo TX-SR705- No Sound

First off, I have to say that since you admit you don't know what you are doing, you need to stop and send this out to someone who does know. You can very easily cause a lot more damage, hurt yourself or cause a fire or shock hazard.

Additionally, if the output transistors are bad, you need the test equipment and knowledge to reset the bias levels and make sure that ALL of the defective parts are found and replaced..otherwise you'll be doing the repair all over again (if you don't destroy the unit or start a fire).

And the only way to properly test the transistors is with them out of the circuit.

I will be nice enough to tell you that the red section is the output transistors, and the blue is power supply regulation.

If you wish to proceed on your own, best of luck but don't get pissed off if things go wrong..you've been warned.

[seanc]

Re: Onkyo TX-SR705- No Sound

Is the unit in protect mode? Have you turned on channel A/B?
If not, I find it strange that the output transistors are shorted.

[ykilde]

Re: Onkyo TX-SR705- No Sound

First off, I have to say that since you admit you don't know what you are doing, you need to stop and send this out to someone who does know. You can very easily cause a lot more damage, hurt yourself or cause a fire or shock hazard.

Additionally, if the output transistors are bad, you need the test equipment and knowledge to reset the bias levels and make sure that ALL of the defective parts are found and replaced..otherwise you'll be doing the repair all over again (if you don't destroy the unit or start a fire).

And the only way to properly test the transistors is with them out of the circuit.

I will be nice enough to tell you that the red section is the output transistors, and the blue is power supply regulation.

If you wish to proceed on your own, best of luck but don't get pissed off if things go wrong..you've been warned.

Thank you for your input. I am a novice when it comes to repairing electronics, but I can eventually figure some things out on my own with the help of people who have a wealth of knowledge in this area. I can test/replace some of the components and trace circuits but that's as much as I can do. I have already discharged many of the capacitors before I mess with it more this weekend.

Sending it off to a technician is an option but I have already decided not to stick anymore money into it. It's out of warranty and I've already bought another unit to replace this. If I can get this working again, then great; if not then only my time is lost.

Is the unit in protect mode? Have you turned on channel A/B?
If not, I find it strange that the output transistors are shorted.

No, it's not in Protect Mode. I can crank the volume up to Max and it will not go into Protect Mode. Also, I have disconnected the Center and Surround speakers and turned off those channels through setup (only using two Front speakers for diagnostic).

[ykilde]

Re: Onkyo TX-SR705- No Sound

I would also like to add that the Video and Audio pass-through works fine with my TV. I have my DirecTV dish connected through HDMI to the receiver and from the receiver to my TV with good video and audio (through TV speakers). I also have tried other inputs using composite and component cables without any problems.

I measured the voltage at the speakers and they're at 0 volts.

Also, one thing I've noticed when I power on the unit is that I hear 3 clicks. If my memory is correct, I recall only hearing two clicks (it's been a few months). The third click is more faint than the initial two.