I just did a post mortem on that errant remote. There was one small Philips screw in the battery box. Hi-Fi was right the unit was glued together. I got the two halves of the unit apart with a sharp blade and screw driver.
There was nothing visually wrong in the remote. It was clean and nothing had been spilt or entered it. The contacts all looked fine and there was no damage nor cracks in the circuit board. It looked to be in new condition visually.
So I have to conclude that the problem must be component failure, or firmware corruption in the remote.
I agree that these units should sense corrupted remote data. I have to wonder if this is more common than we realize. I would never have thought this was the cause of the problems. I only realized it when the other unit malfunctioned with this problem remote. So it really was just blind luck this problem was identified.
The AVP remains snappy with the remote from Remotes.com. I really like that remote. I think I may order another and one of their remotes for my Marantz AVP 7705.
I'm not that impressed with those Marantz remotes, all of them have to be pointed pretty straight at the unit. My gear is to the side in the AV room. To get the unit to respond, I have to stretch my arm out and get the line as straight as I can. It will not work from the third row.
The Remotes.com remote on the other hand seems to work from any position in the room and has a longer range. They seem nice high quality devices.
This has been a surprising discovery for me. So we have this possibility to add to responding to posts about errant AVRs and AVPs.
Sound United or their new owners, need to make their units non responsive to corrupted remote commands, and certainly not perform in the manner I described, with lockups etc.
Sensing and reacting to corrupt codes adds levels of complexity that we don't want but as I wrote, only a few companies make IR control devices, not Denon, Marantz, etc and even fewer that make remote controls- Celadon, URC and a few others.
How old were your batteries? Has that old remote been dropped? That can dislodge solder joints and as an example of a remote series you would NEVER want to drop, the URC Apollo and Gemini models had an IR emitter board that could separate from the main board when dropped on the IR lens.
BTW- if you have a video camera (old, new, in a phone, etc), aim your remotes at the lens and watch as you press buttons- newer smart phone cameras don't pass IR, but old ones do and you'll see a gray dot where the emitter is sending the light. You'll be able to see the angle of coverage and most OEM remotes have one, two or three LED bulbs, all aimed more or less straight out from the end. Aftermarket remotes usually cover a much wider area. If you use an iPhone, use the camera lens on the face because the one(s) on the rear won't work for this. This is one of the first things people in custom integration do if a remote doesn't work- some remote manufacturers hand out IR detectors and URC sells one that's far too expensive, so very few people carry anything other than their smart phone.
The IR receiver will only respond to correct codes- these devices aren't, and don't need to be, particularly smart and as an FYI- almost all remotes repeat the commands three times, every time the button is pressed. Light reflections can confuse the device being controlled and one of the easiest ways to cause something to respond poorly is to allow Sunlight to reach the IR window on the front. Some equipment has an IR jack on the rear but, IMO, ALL equipment should have this because it completely takes line of sight and IR out of the equation. This, however, requires the use of an IR repeater or a hub-based remote but it's extremely reliable- it only needs a cable with a 3.5mm plug on each end unless the repeater has a Euro connector.
