I’m now 15 years removed from my days as a hardware/software support professional–and hadn’t ever run into anything remotely like this anyways–so wanted to open this up to folks that are still in that game. Or in the electrical engineering game. Or, I suppose, in the game of letting Mllz know that he’s a freakin’ idiot for not considering such-and-such obvious solution to the problem at hand.
Description of issue:
A few times a day, my computer monitor goes black for a few seconds (and occasionally longer) when the door to my office is opened. It’s not every time my office mate or I open the door, but the opening-of-the-door is the only thing that seems to trigger it. The monitor doesn’t lose power while it’s blacked out, nor does it appear to lose the signal altogether (when this particular monitor loses the signal from the computer, the power light changes immediately from blue to orange; in these outages, it stays blue).
[li]Monitor is a ViewSonic 23" flat panel, about 4 years old, raised about 5" off the desk on a metal monitor stand[/li][li]Computer is a 2013 MacBook Pro running OS X 10.9.5 and also Win7 via VMware Fusion[/li][li]3’ HDMI Cable connects the two[/li][li]The door is heavy, steel, and windowless, 30" wide and maybe 9’ tall. It opens into the office, coming within about 2’ of the laptop at the closest part of its arc.[/li][/ul]
I’ve tried jiggling both ends of the cable, the computer, the monitor, and the desk, to test for loose connections or bad cable, but none of these replicate the issue. Nor does it happen when I deliberately try to replicate by opening the door repeatedly. Doesn’t happen to my office mate at all, though he’s got a completely different setup (and, of course, doesn’t occupy the same physical position in the office as me).
I haven’t tried swapping out the HDMI cable yet because my spare is at home, and, well, when I’m at home I’m simply not thinking about my troubleshooting a pesky issue with my work monitor. So I never think to bring it in. But you’re all right here, and can probably provide advice that does not require me to write myself a note on my hand!
So what gives? Electromagnetic thing due to that steel door moving? Air movement from the door opening? Or just a cable/connection thing that doesn’t reveal itself by the standard jiggle test? I’m totally cool with replacing the cable and/or monitor, just don’t want to do so unnecessarily!