Yamaha HTR-5760 Receiver Repair

[Helblind]

Hey all!

I am looking for some guidance in repairing a Yamaha HTR-5760 receiver that I took out of storage. I am a relative newb but I do have some experience replacing boards and soldering, and I do have a multimeter and the service manual. However, the electronic diagrams are gibberish to me and I am unsure where to start. I am hoping there is a blown capacitor or something similarly easy I can replace.

Anyways, here is what is happening:

The unit turns on for a second then turns off. There is a small click when it turns on and off coming from the board behind the power supply, but I believe I remember those clicks as normal. It turns off with speakers connected or not.

I am able to access DIAG mode, but only in protection cancel mode. In DIAG, there are a few findings with potentially various levels of significance. When I switch into menu number 8: VFD Check, there is a louder click coming from a Omron G5PA-28 power relay(?) at the back on the unit. It clicks again when I move out of menu 8. As well, in menu number 9: TEST ALL, when I scroll through the individual tests, the relay clicks when I reach TEST PRES L or R, but not when scrolling between the two of them. I have no idea if this is normal behaviour.

The last noteworthy finding is on menu item 11: AD DATA. The DC is listed at 7, well within the parameters of 1-13. However, the PS constantly switches between 21 and 22, 21 being out of the parameters of 22-47. This, along with the error on entering the DIAG mode of PS PRT : 022 E, seem to point to a potential problem with the power supply or something which triggers the protection function.

So, I am wonder what my next steps might be and/or recommendations to further understand the issue. I can take some voltmeter readings but I am unsure were to take them and what I should be looking for. Any assistance would be appreciate!

Thanks!
Helblind

[mzacharias]

Check the various voltage regulators for low output.

[KevinA]

Sounds more like a shorted output stage, or d.c. offset on one (or more) outputs.

Locate the 0.22R wirewound emitter resistors (3 pin resistors). Measure the voltage on any pin with reference to ground. Anything more than a few mV, and you have a fault on that output channel.

[mzacharias]

Sounds more like a shorted output stage, or d.c. offset on one (or more) outputs.

Locate the 0.22R wirewound emitter resistors (3 pin resistors). Measure the voltage on any pin with reference to ground. Anything more than a few mV, and you have a fault on that output channel.

Yamaha's don't behave that way with a shorted channel. The high current protect shuts the thing down before the display can even come on, and the diagnostics cannot be accessed until the short is cleared.

One channel DC offset is certainly possible, and in Protect Cancel mode would be easy to find; I suggested checking the regulators first because that is what I would do, having done Yamaha warranty service for over twenty years.