I will do this as soon as I get in front of my TV. Do you know how I can get the ARC working on my
TCL 75r615 TV with my Onkyo NR-686? It worked to four hours over the weekend but no longer.
I'm not sure where your support is located on this site.
To use ARC you have to connect the HDMI cable from the AVR into the TV's HDMI port that is ARC enabled. According to the manual I could download, that is HDMI 3, which is the port directly above the USB port and below the optical out jack. And your Onkyo has two HDMI out jacks, but only the one labeled Main is ARC-enabled.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
I have my system connect properly, new certified cables and both ends plugged into ARC ports. As I mentioned before it all worked to a few hours then stopped. When I deselect CEC under HDMI the TV speakers turn back on so I know that ARC tries to work. Everything I've tried doesn't work,I know it's not my receiver because to work with another TV.