My yamaha rx-a720 receiver buzz after 2 hours of running

SOURCE: Yamaha RX-V995 receiver turns on & then powers off 2 seconds late

I suggest you run self diag.  press [FM/AM] key + [Input mode] key and press the [power/standby] switch.

ps prt = power supply problem
dc prt = shorted output or leakly cap in channel
tmp prt means to hot on heatsink

you'll likely have to measure the resistances of the output FETs to find a short, 

SOURCE: Yamaha RX-V1400 receiver powers off, in case it becomes louder

Hey, yeah that can be frustrating.

When you turn it up do you hear the relay or a clicking sound, then you turn it on and it comes back below the +2db?

Try unplugging All the speaker wires from the unit. Turn on the unit and listen for the click.
after the click, turn it up past the 2+ db mark and see if you hear it click or shut down. If it did not click off, then suspect a shorted crossover on one of your speakers.
2nd test is to plug in One speaker, and test it at high volume, it will not harm it. If it shuts off disconnect that speaker and try another. Only one at a time.
If it works at high volume, you need to isolate one of your speakers and i bet it has a shorted crossover that has been cooked. P.S. If one is bad, suspect they will fail at a later date.
If they all fail, use a friends speaker and try it before sending it to a repair shop.

P.S. i found one on ebay i think you can get for under $100 bucks in the box.

http://cgi.ebay.com/Yamaha-RX-V1400-7-1-THX-Select-Receiver-MINT-Condition_W0QQitemZ330311512027QQcmdZViewItemQQptZReceivers_Tuners?hash=item330311512027&_trksid=p3286.c0.m14&_trkparms=72%3A570|66%3A2|65%3A12|39%3A2|240%3A1318

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Frank Fulton

• 1114 Answers
• Posted on Dec 29, 2009

SOURCE: Yamaha receiver RX-V663

Make sure you have an analog RCA audio cable from the source to the receiver. Digital coaxial or optical will not work for zone 2 or zone 3. By adding an analog cable it will not affect your main zone, it will always go to digital first. Hope this helps

Testimonial: "great feedback. "

SOURCE: Yamaha rx-v456 av receiver, shut down with optica cable

Does it work without PS3 attached?
When receiver turns off, it is usually due to badly connected/configured speakers. Try powering on the receiver without speakers.

SOURCE: Yamaha RX-V365 unable to receive 5.1 audio from TV with HDMI

If you're expecting multichannel sound FROM THE TV instead of from the source you're watching, it's not gonna happen. TV's are notoriously poor sound sources. This one is no different.

Multichannel TV-related audio is best found at its source - cable / sat / dvd / bd....

I run video-related audio from my video sources directly to my TV and their audio directly to my receiver. Specialization yields best results.

I'd recommend skipping the Receiver for video, too, as it adds a lot of opportunity for HDMI-related incompatibilities and sound syncing problems. The more interconnects in the path, the more distorted it will become and the more opportunities for problems. Plus you can bypass the receiver and listen to lo-fi programming like news and weather through the TV's speakers if you like. Save a buck on electricity.

Just curious, which HDMI on the receiver is connected to your TV? Input or Output?

This note is on Page 11 of the manual:

Audio signals input at the HDMI jack are not output from any speaker terminals but output from the connected video monitor. To enjoy the sound from speakers connected to this unit,
-- make an analog or digital connection besides the HDMI connection (see page 13).
-- mute the volume on the connected video monitor

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"Check SP cable." -- The unit is perceiving a short circuit. Are your speaker impedances sufficiently high? Disconnect the Front Right speaker and try raising the volume again. The speaker may be blown or the cable shorting.