Saturday, September 21, 2013

Gravity Always Wins

It's very common that when CRT monitor is being rotated (turning to portrait mode) while it is turned on it becomes discolorized, the color tends to go back to normal after a few minutes. So when rotating a CRT monitor, it's better to turn it off first. The components of a CRT monitor which are very heavy, tend to be stressed when rotating the CRT monitor, the stressing effect is more pronounced when you are rotating the CRT monitor while it's turned on.

That discoloration doesn't happen on modern LCDs, so it's surprising when a colleague is rotating his LCD monitor, the screen color is turning yellowish. There got to be an explanation for the discoloration, and why most often it's yellowish, why not some color like fuschia? :p

I have a pivot-capable LCD monitor at home, but there's no discoloration happening even I'm rotating the LCD while the power is on.

So what's the difference between the LCD at home and office? The LCD in our office happens to use VGA cable instead of HDMI or DVI. VGA cables tend to loosen when not screwed tightly. And those pins in VGA cable has their own color task. Those pins carries signals for colors. For the illustration:

So that's the explanation for the yellow. When rotating a VGA cable-equipped LCD monitor, the VGA cable is loosening a bit, the RED and GREEN pin still sticks, while the BLUE is loosening a bit when the VGA cable is being oriented vertically. RED + GREEN === YELLOW, that's for 90 degree. When rotating to 180 degree the screen discolorized to CYAN, i.e., the RED loosens, leaving the display with just two color signals instead, GREEN and BLUE, which when combined becomes CYAN.

As for why discoloration doesn't happen on HDMI and DVI for that matter, both cables are not analog, i.e. they don't carry signals, what they carries are data instead. So there's no such thing on an HDMI-equipped LCD for a BLUE pin that loosens while rotating it.

Happy Coding! ツ

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