Monitors, HDMI cables, and HDMI Switches - Something is wrong somewhere

rayden54 · June 28, 2017

I bought a monitor off Newegg. Refurbished. It's an LG 34UM58-P. I've been having problems, but I can't track down the source. At first I assumed it was a problem with the monitor, so I RMA'd it and bought a new one. But, I'm still having the same problem with the new one.

Essentially the problem is this: when I try to switch from HDMI Input 1 on the monitor to HDMI Input 2, the monitor just stops responding. Sometimes the screen just goes black. Sometimes the on-screen menu thing'll popup, but won't respond. Sometimes the "No input detected" message pops up. Only way to get the monitor to do anything is to unplug something.

I've tried every combination I can think of, and the problem only seems to occur in one specific case:

HDMI cable A (10 ft braided) running from HDMI Input 2 on the monitor to the output of an HDMI Switch and with another device plugged into HDMI Input 1 on the monitor (PC, console doesn't matter, but something has to be plugged into both inputs).

As far as I can tell, the problem doesn't happen when I do any of the following:

HDMI cable A running from HDMI Input 1 to the HDMI Switch and another device on HDMI Input 2. (In other words, just switching the inputs around)
Switching out HDMI cable A for a different cable. Same setup as the original.
Running HDMI cable A directly from HDMI 2 to a device (bypassing the HDMI Switch) with another device plugged into HDMI Input 1.

I can't tell if that means the problem is with HDMI Input 2 on the monitor, HDMI cable A, or the HDMI switch. I can say that I had the same setup with HDMI cable A and the HDMI switch with my old monitor (an Acer H226HQL) with no problems.

I guess I can buy a new HDMI cable to replace HDMI cable A (?). It's the only one I have that's long enough to reach.

I could just switch the inputs, but I was having a different (but probably related) problem when I did. A message would randomly pop up that'd say "Power is off in 5 minutes to save energy. Press any button to prevent the power off." I haven't had that problem with the new monitor, but I don't know if it's gone or not.

Sorry this is so long. I just want to know what the problem is.