Help! What's this inside Onkyo TX-DS797 with pulsating output.

[ChefE]

Hello. From GW I got an Onkyo tx-ds797 a/v receiver. Came home and cleaned it inside and out, then hooked it up with some sources and speakers. I got sound by "direct" only. Otherwise sound output on all channels from analog or digital sources yielded a intense rapid pulsating sound- not high or real low frequency but a uniform...wah wah wah wah wah wah wah wah wah.....etc. I turned the power off! Unplugged everything and opened it up....fuses are correct, general apperence of solder joints seem ok, parts don't appear burnt or swelled- except this part looks odd. I've not seen this before. What is it? It's reads 5.6V or 5.5V and the green board has lettering G or C or 6 then 7701. ("G7701"). The wire legs attached look rusted.
Not sure what to do at this point to remedy the receiver. Maybe I'll just return it? If so my curiosity will remain and used for future reference just in case.

 

[audiotemp]

That part is probably a supercapacitor, basically a rechargable-battery-like capacitor that maintains settings in memory when the unit is off.

 

[ChefE]

Thank you. Would that part contribute to the intense cyclic produced sound?

 

[audiotemp]

Thank you. Would that part contribute to the intense cyclic produced sound?

Well, it's possible.

If it works and sounds OK in direct mode then the amp is probably OK. A lot of the other stuff will be digital and hard to do anything with.

Google Onkyo TX-DS797 reset and figure out how to do a factory reset---if the settings are messed up that might help. You can look for a user manual to download and for hints about what goes wrong with those units. You can probably download a service manual as well, perhaps at hifiengine. You might get lucky but it could easily be non-repairable.

 

[MBuras]

Had one of these new. I remember having to take it into a certified repair shop for a factory service recall not long after purchase. Can't remember the context of the recall or if it's related to your issue but maybe a search of the inter webs will reveal something. Good luck!

 

[ChefE]

I ended up returning the Onkyo back to GW on the very last day to return that item. I asked them if I could rebuy it and return it in another 7 days if I can't fix it. They said no. Maybe that was a blessing. Sounds like this particular model might have been a lemon after all.
Thank you everyone for helping. I appreciate it.

FYI: the GW was in Costa Mesa. Buyer beware.

 

[stereoguy70]

Thank you. Would that part contribute to the intense cyclic produced sound?

Sounds like the amp is in oscillation if you ask me. You need to look deeper into the bowels of his unit and see if any caps are junk or resistors burned, or discreet transistors that are dead/shorted/open.