Video help needed - turning off projector/receiver turns of monitor too

[Tuthmose]

Greetings,

I’ve got a conundrum I’m hoping somebody can help with.

I built an A/V setup in my classroom centered around a PC (my build: Windows 10 Pro w/ a GTX 750 GPU), a Yamaha RX-A760, and an Epson EX 9200 projector. The computer sends a signal via HDMI to the receiver, which then sends it via HDMI to the projector. A *separate* hdmi cable directly connects the computer to the 24” Dell IPS desk monitor.

The problem: Suddenly, out of the blue, turning off either the Yamaha receiver or the Epson projector turns off the desktop monitor too.

It never use to work like that . . . I’d work at my desk with the projector off, and the monitor worked fine. I had Windows 10 and the nVidia software set to see the monitor as the primary, and clone it to the projector. Then one day, 4th period, something changed. I turned off the projector, - **poof** - no monitor signal either.

Troubleshooting:

1. I checked the Graphics settings. All is correct – monitor is primary, cloned to projector
2. I did a clean reinstall of the Graphics Drivers, using DDU uninstaller to be sure I got it all
3. I changed cables, and which ports they were plugged into on the GPU
4. I made sure CEC HDMI control is OFF on the Yamaha Receiver

Here is what I noticed in my troubleshooting: if I physically disconnect the projector (powered up or not) from the Yamaha receiver, the monitor signal is still absent. If I power off the receiver, the monitor signal is still absent. But if I *physically disconnect* the receiver itself from the PC, the signal returns. Soo . . . it seems the receiver is somehow the culprit. But why? HDMI control on the receiver is off. What the heck gives? How do I fix this?

Any suggestions or help would be greatly appreciated!