PROBLEM: in the absence of a signal on the chosen HDMI input, the Samsung UN55EH6000 automatically switches its input source to OFF-THE-AIR (i.e., TV) mode.
(Let me admit up front that my problem could have been avoided if I had RTFM--such as it is.)
I'm using my Samsung UN55EH6000 as a monitor, connected to my Onkyo surround-sound receiver (SSR), which switches five HDMI devices (three DVRs, a DVD player, and a Roku box). No antenna is connected because I don't receive good OTA signals.
After unboxing the TV, I powered it up. It immediately jumped directly to the "Plug & Play" (P&P) setup wizard (which IMHO is poorly documented). Here, with an incomplete understanding of what I was doing, I inadvertently configured the TV so that when I press the "Source" button on the TV remote, I'm give two choices: HDMI and TV. This configuration works fine until I switch my SSR to any inactive input (and sometimes just switching channels on a DVR), or say, to an input whose device happens to be turned off (e.g., my DVD player). At that point, the Samsung automatically self-selects "TV mode," which, in the absence of an antenna, just fills the screen with snow.
I went back and read the setup instructions carefully and I see that at the Antenna Source screen I must have selected "Cable or Air" when I should have selected "Skip" (to skip this config screen). So, I figured no-big-deal: I'll just run the P&P config again--this time actually skipping the Antenna Source screen. BUT NO SO FAST! Once the P&P Antenna Source screen has been setup, subsequent visits to the P&P process skip the Antenna Source screen entirely.
So, It looks like I'm going to have to reset the entire TV. (I'm guessing that's what the Support->Reset menu item does.) I've done quite a bit of tweaking of various picture-quality settings, so before I reset the entire Samsung, Does anybody know a way to reach the factory-default setting of the Plug & Play wizard? Or, better yet, how to get back to the original Antenna Source screen?