20 Most Recent Harman Kardon AVR 635 Receiver Questions & Answers

Is seems certain that the main processor or the display sub- processor has failed and so shows up the entire characters on the display panel.
You have to probe to see the working of the processor, check the +5 on the IC and also the Oscillation frequency to confirm the IC as defective.

There maybe something wrong with pins of either the camera or the charging dock. Try to check whether the socket is providing power "with a tester".

make sure you have full surround enabled

Check the speaker wiring on the back of unit for shorts, if okay! the audio output ic's are defective, "one or more" at this stage you need someone to go through the device to find out the extent of the problem.

You can get an RCA splitter; or just use one of the 2 sub inputs on the sub amp.

I had this exact issue.
I was using the digital 2 input for sound. (Toslink cable from my cpu).

It seems I inadvertantly muted the sound on the pc, and this caused the "unlock" message with the L-R speakers flashing on the display.

I restarted my pc; and then unmuted the sound.
3 seconds later; the L-R stopped flashing and I now have sound on Vid2.

Generally speaking, an amp protects itself from heat, shorts, overloads and operator exuberance by refusing to turn on or stay on.

Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.

You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.

If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.

If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'naked'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.

Check for loose speaker connections at the speaker as a root cause for intermittent shutdown.

please be more specific...is it otherwise functional except for the display, or is the unit completely dead?

Details on how to do this will probably be in the service manual obtainable from
www.mauritron.com

The receiver is shut down by its own autoprotection system. The system is triggered by only 3 things:
1. there is a short one one of its speaker outputs. Not your case, you wouldn't be able to start the unit at all because a shorted speaker doesn't fixes itself.
2. the receiver overheats. Fortunately this is easy to fix - just remove the top and sides cover (a few screws on the bottom and the rear are holding it in place) and clean the inside thoroughly. Use a brush with long, soft hairs and a vacuum. Don't put the vacuum directly in it, you might hit something and the parts inside are fragile.
2. the amplifier components have aged and are starting to draw more current than they are supposed, triggering the power source's short protection. Unfortunately this is a major problem that can be fixed only by a trained repairman - it will have to identify and replace the aged parts - most likely the filtering and final capacitors. You must take the receiver to a repair shop.

Please check you speakers, the connection and the selection of the speakers. If all seems right you might have to check for failure of fuse or loss of contact in the relay or failure of the output relay.
Please check this out. Good day