It has happened on and off for a while. The unit has an ir blaster on it, URC MRF-350. Using a MX-450 remote. Now it no longer responds to anything. Even old remote gives no results.
Do I need to replace the ir sensor? Can I use a sensor from another piece of equipment if it matches the output?

I can't stand to get up to turn on something anymore...

Thanks.

Next to my desk in my office I have a rack that's got a Nakamichi TA-4A and I don't have a remote for it. It's sooooo hard to reach over and adjust the volume! I'm jsut glad the volume control is on the near side.

I suppose I should look up the codes and program my reference Pronto for it. I have no other use for that remote!

Anyway,
the key here is that if the factory remote doesn't control the unit any more either, then the problem is serious. Check with a phone camera to be sure the 350 and the factory remote both actually output IR; if not, then yes, your IR sensor is bad. The challenge here is to get THE replacement IR sensor that's built into the unit and to replace it. It's not likely, but remotely (yuk yuk) possible that a sensor from another unit would work.

Not familiar with your model, but there might be a 3.5 mm jack on the back of the unit that would allow you to take a 3.5 mm at either end cord and go from the mrf to the onkyo, bypassing the target on the front....

The TX-DS595 does not an IR input in the back although that was a great suggestion Fred.  Do a clear reset to the receiver by holding down the power button and video 1 input button at the same time for 5 seconds.  Then try the original remote again.

Thanks Ernie, Fred and Wil. No response from the unit when cleared.
Did go into debugging mode (accidentally) and had a H8000A LLL 231 show on the display. Can't find that anywhere.

Right now I'm using the tv audio, and it's killing me.
:)

did you ever find a solution - I have the same receiver and get the same message...holding down video 1 and power at same time did not clear it - stays in protect mode. Thanks

Throw it in the garbage. That thing sucked when it came out...It's gotta really suck now. 

+1000000000000000000000000000000000000000000

That was an entry level receiver from 16+ years ago.
I am afraid in this case, the others are correct. It is junk and has been junk for quite a long time.
If money is that tight, there are lots of choices on ebay. You can get a MUCH newer, upscale, and working receiver than it would cost you it fool with repairing that ancient Onkyo.