Q After I fried our Panasonic home theatre receiver (which my tech-savvy brother had selected for us), my husband bought a used Harman/Kardon AVS 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

C|net has some good reviews:
http://reviews.cnet.com/av-receivers/harman-kardon-avr-635/4505-6466_7-31249751.html

After doing a quick search on the subject the first few threads seem to point towards some worth while 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,

<edit>

dantothe4thpower - 20 October 2009 11:34 AM

google.com or call harmon kardon.

what a soltion…

+1 for TechSource answer.  Maybe when the Panasonic “fried” it took some of your speakers to the cook-out. When a receiver or amplifier goes into meltdown it can produce some damaging currents at the speaker outputs. This current may damage the speaker’s internal components and/or drivers. Sometimes the damage is evident in that the speaker no longer works at all. I recently had a customer complaining that the system would shut down if he raised the volume past a certain level. (Not loud). The amplifier’s protection circuit was kicking in and shutting down the audio as it was sensing an unusual load. Upon inspection we found a midrange driver in the centre channel to be defective along with a shorted out coil in that speaker’s cross-over network. The speaker still made sound but it presented a load to the amp that was unacceptable. It was near impossible to tell the speaker was defective with all 7 channels working so we disconnected all the speaker save for 1 and checked all individually at different volumes. The centre channel caused the amp to go into protection mode and the sound was bad from this speaker.