Do contrast/brightness settings affect life span of CRT?

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Level 6

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Do contrast/brightness settings affect life span of CRT?

Will I shorten the life of this CRT if I have the contrast and brightness turned up relatively high? Conversely, will I extend its life if I keep contrast and brightness on the muted side? Intuitively, the answer would seem to be yes to both, but wondering if anyone has any hard information on this.

And do these settings affect the PAV board/flyback transformer lifespan? (BTW, I run a fan over the top of the case to help dissipate the heat).

Thanks.

iMac G3/400 "It takes a licking and keeps on ticking", Mac OS X (10.4.11)

Posted on Jun 2, 2009 12:06 PM

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Answer 1

Jun 2, 2009 1:08 PM in response to WZZZ

I don't know the answer statistically, but you should have the contrast and brightness set to whatever is comfortable for your use, and have Energy Saver set to sleep the display when the iMac is on but inactive. Don't just use a Screen Saver because the display is still powered ON. With normal use (the display set to a reasonable brightness), the real world difference on CRT longevity is probably not significant.

CRTs are affected by magnetic fields, so don't put unshielded speakers (and things with potentially unshielded speakers such as a speaker phone or answering machine) or any other magnets too close. The iMac's CRT itself can build up magnetic fields, so if you notice something unusual in the displayed image, shutting down the iMac, letting it cool, and restarting should degauss the display.

http://support.apple.com/kb/TA22241

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Answer 2

WZZZ Author

Level 6

13,238 points

Jun 2, 2009 2:02 PM in response to Kenichi Watanabe

Thanks Kenichi,

I'd actually discovered the perils of magnetic fields and CRTs when I first set up this fan. When brought too close, it would make the screen shimmer and vibrate like crazy. It's about two feet away now with no shimmering or effect on the screen at all. Of all things, I think that fan should help the most. Too bad Apple went completely to convection cooling for the G3 and others. These things do get hot at the top.

The iMac gets shut down overnight, so that should probably take care of the degaussing. I don't use a screen saver anymore; just have display to shut off after 5 minutes.

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Answer 3

Jun 2, 2009 2:48 PM in response to WZZZ

The older iMac G3 tray-loader has a fan (it is quite large and it is a bit noisy because of it). The next model, the iMac G4, had a fan too (a small quiet one). The only Macs that were convection cooled (as far as I know), were the original compact Macs from 1984 to Mac Plus (before the Mac SE) and the Power Mac G4 Cube. Steve Jobs likes quiet computers; his first Macs had no fan and the first new Mac model after he came back to Apple had no fan... interesting (but I guess a bit off topic).

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Answer 4

WZZZ Author

Level 6

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Jun 2, 2009 2:51 PM in response to WZZZ

This is leading on to something else, but I've been wondering, for some time, about seeing a consistent pattern of faint, stationary, closely spaced ripples or wavy lines, fanning out over the entire screen. This is most noticeable at start up on the first gray screen. My wife seems to think it's always been there, from day one, but that it's, perhaps, becoming more obvious now. This is hardly, or not at all, visible on the desktop ("solid aqua graphite") or on a blank, white browser page.

The articles you linked on magnetism don't seem to describe anything like this as the result of magnetic interference. Don't know what to make of it.

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Answer 5

Jun 2, 2009 2:58 PM in response to WZZZ

I believe that is the +moiré pattern+ effect. I found this web page that explains it rather nicely.

http://www.displaymate.com/moire.html

I have seen it too, mostly at startup like you described. It never bothered me when the iMac was actually displaying an image.

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Answer 6

WZZZ Author

Level 6

13,238 points

Jun 2, 2009 3:50 PM in response to Kenichi Watanabe

Wow. Thanks. Very relieved. I thought it was a sign of something of ominous. 🙂

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