What’s Wrong With My A/V Receiver?
Receiver often refuses to put out sound, freezes, and says "unlock" after cycling through start-up messages.
Harman/Kardon AVR 635 Receiver
October 28, 2009 by CE Pro

Q. After I fried our Panasonic home theater receiver, my husband bought a used Harman/Kardon AVR 635 on eBay.

It often refuses to put out sound. Some of the time it freezes up completely. Other times, it seems to come on, the screen provides the right message, you can adjust the volume and the numbers go up and down, but there’s no sound.

Sometimes when the screen turns on, after it cycles through its start-up messages, it says “Unlock.”

I have tried resetting by unplugging from the power, which works sometimes, but not always. It worked yesterday, but won’t work today. I wonder if the “Unlock” message has some meaning I cannot figure out. I cannot find anything about that in the user’s manual.

I suppose this problem may be why the previous owner was selling this receiver on eBay. Any suggestions? — Ellen McGuffie

A. Morgan Harman of The Tech Source offers this advice:

CNET has some good reviews, including one on the Harman/Kardon AVR 635.

After doing a quick search on the subject, the first few threads seem to point towards some worthwhile areas to consider.

The “Unlock” message seems to appear when you are needing to enter the setup mode. This may be because the amp is trying to set the digital audio to the correct input. Perhaps you have recently changed the cabling and started to connect some sources with HDMI?

Some of the threads seem to suggest that if you go ahead and enter the setup mode by using the remote when prompted with the “Unlock” request, you then set the audio to the input and that should keep this from happening.

Worth a try. Happy tuning.

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