Thanks Otto and Joe. I had to look up CEC after your first reply, Otto. Now I know what it is, and it is automatically enabled when I selected "yes" to ARC in the Onkyo avr initial setup. However, there are some options in the Onkyo hardware setup. If the problem persists, I will call Onkyo support to make sure the settings are correct (though they seem to be). I also looked in the manual for trouble shooting, and it recommends unplugging the HDMI cable and doing resets if the issue persists (same thing Sony support recommended). I'll see if I have to do that in the future. Joe, I will see if I have an optical cable around (I think I do) and try what you advise if the issue persists. May be a while before I get to it. Thanks for that tip.
One very simple (and kind of stupid) thing occurred to me. The fit into the cabinet is tight at the back of the avr, causing the HDMI cables to bend and perhaps putting some stress on them.
I wondered simply if this might contribute to the problem, and so I moved the avr a bit forward and tried to ease the bend on the cables. I'll see if this helps.
My wife suggested when we set up the avr that I cut a bigger rectangular window in the back of the cabinet (which is nothing fancy), rather than stressing the wires to go through the various holes I've drilled. The window would not be visible and make life a lot easier, and also ventilate the cabinet better. Simple... So sometime in the near future I will do that. I did search this forum for thoughts on the efficacy of elbows, and read both of your comments (o great gurus of connectivity) on elbows in another thread; so I will avoid those for now. Thanks again.
Last edited by Buteobander; 06-16-2019 at 09:38 AM.