CRT life

[Halfgaar]

Hi list,

I've read in a DPMS screensaver help file that blankscreen screensavers are
not such a good idea, because when the CRT filament is still energized when
there's no picture, actually causes the life of the CRT to shorten. Why is
this?

TIA

Halfgaar
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[Halfgaar]

Halfgaar wrote:

I've read in a DPMS screensaver help file that blankscreen screensavers
are not such a good idea, because when the CRT filament is still energized
when there's no picture, actually causes the life of the CRT to shorten.
Why is this?

I've got an addition to my question. Does this also mean that DPMS mode
suspend is not good for the monitors's life, seeing as how in suspend mode
everything is powered down, except the filament.

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[Halfgaar]

Halfgaar wrote:

Halfgaar wrote:

I've read in a DPMS screensaver help file that blankscreen screensavers
are not such a good idea, because when the CRT filament is still
energized when there's no picture, actually causes the life of the CRT to
shorten. Why is this?

I've got an addition to my question. Does this also mean that DPMS mode
suspend is not good for the monitors's life, seeing as how in suspend mode
everything is powered down, except the filament.

Hmm, it seems that the CRT faq on repairfaq.org disaggrees with this
completely: "With modern CRTs, the filaments can be left to minimize the
time needed for a picture to appear since this doesn't affect CRT life very
much." (found at http://repairfaq.ece.drexel.edu/sam/crtfaq.htm#crtlif).


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[Jerry Greenberg]

This can be a complicated issue.

There is more to the CRT than just the heater. When there is cathode
current, the ware is higher. There is a minimum cathold current when
there is no brightness on the screen. The tube has to be biased
slightly on all the time when working, even though it is in black.
When there is some luminocity on the screen, there is a greater amount
of cathode wear in the electron-gun.

Having a black screen saver will infact save some amount of catholde
wear. If you have a small image on the screen that is moving around,
this would introduce a bit more cathold current, but it would not be
the same amount as having a full screen of white.

The best solution is if the screen is not being used for about a 2 to
3 hour period, turn it off, or have the Windows power savings utility
turn it off. Cycling the monitor power on and off, can introduce a
greater stress on the support components, and the tube, rather than
simply leaving it on. This gets in to duty cycle statistics on the
wear of the electronics, and tube. This can get very complicated in
many cases.

The standard CRT should last about 30,000 hours. At this time factor,
the brightness output should be about 50% of the nominal. This figure
is with the brightness set to normal, and the contrast at about 50 to
70% of its maximum rage. If the monitor is used at about 10 hours per
day, it should last about 8 years.

In reality these monitors will last about 5 to 6 years. There are many
support components that can go wrong before the tube does. Cycling
the power off and on will also cause the monitor to fail quicker.
After about 6 years of normal use, many of the capacitors start to go
bad in monitors and TV sets. Then there are many other types of
components that can fail. Since most monitors, unless they are very
expensive and high end models, they are designed to not be serviced.
In the low to medium end monitors, many of the manufactures don't sell
the parts for out of warranty servicing.

Enjoy the monitor. The way things are going obsolete these days, in a
few years, your monitor will be useless, and may have to be changed
anyways.


Jerry Greenberg
http://www.zoom-one.com

--




Halfgaar <voor_achter@yahoo.remove.com> wrote in message news:<br2gur$ml$1@news1.tilbu1.nb.home.nl>...

Hi list,

I've read in a DPMS screensaver help file that blankscreen screensavers are
not such a good idea, because when the CRT filament is still energized when
there's no picture, actually causes the life of the CRT to shorten. Why is
this?

TIA

Halfgaar

 

[Asimov]

"Jerry Greenberg" bravely wrote to "All" (08 Dec 03 15:02:21)
--- on the heady topic of "Re: CRT life"

JG> From: jerryg50@hotmail.com (Jerry Greenberg)

JG> This can be a complicated issue.

No kidding! If we look at basics, a crt is in fact a vacuum tube.
There are special recommended precautions on how to operate power
tubes and a crt is certainly a power tube. Primarily, the matter of
allowing the cathode to reach operating temperature before applying
plate voltage, this in order to avoid cathode stripping, among other
things. This aptly applies to a crt to prolong its life. Even some
tv's actually test the emission before unblanking the picture. Some
early "instant-on" tv's left a little current flowing through the
heater to keep it warm since most wear and tear happens at turn-on.

.... A picture is worth a 1000 words (but it uses 1000 times more memory!)

 

[Halfgaar]

Jerry Greenberg wrote:

This can be a complicated issue.

There is more to the CRT than just the heater. When there is cathode
current, the ware is higher. There is a minimum cathold current when
there is no brightness on the screen. The tube has to be biased
slightly on all the time when working, even though it is in black.
When there is some luminocity on the screen, there is a greater amount
of cathode wear in the electron-gun.

Having a black screen saver will infact save some amount of catholde
wear. If you have a small image on the screen that is moving around,
this would introduce a bit more cathold current, but it would not be
the same amount as having a full screen of white.

I can understand this misundertanding... I was talking about that no picture
at all is worse than *a* picture. The help file of that screensaver said
that displaying a blank image for too long is bad for the filament. But the
CRT-faq on repairfaq.org seems to dissagree and somehow I put more fate in
the latter.

A topic for confusion by the way: I call an image blank when there is no
picture. Perhaps the author of that helpfile calls a white image blank...

The best solution is if the screen is not being used for about a 2 to
3 hour period, turn it off, or have the Windows power savings utility
turn it off. Cycling the monitor power on and off, can introduce a
greater stress on the support components, and the tube, rather than
simply leaving it on. This gets in to duty cycle statistics on the
wear of the electronics, and tube. This can get very complicated in
many cases.

For most electronics this might be true, but this seems to be a
misconception about monitors. You shouldn't power cycle to often of course,
but a few times a day is not so bad. A CRT wears down through use very
quickly. The disadvantages of leaving it on are greater than the
advantages.

The standard CRT should last about 30,000 hours. At this time factor,
the brightness output should be about 50% of the nominal. This figure
is with the brightness set to normal, and the contrast at about 50 to
70% of its maximum rage. If the monitor is used at about 10 hours per
day, it should last about 8 years.

In reality these monitors will last about 5 to 6 years. There are many
support components that can go wrong before the tube does. Cycling
the power off and on will also cause the monitor to fail quicker.
After about 6 years of normal use, many of the capacitors start to go
bad in monitors and TV sets. Then there are many other types of
components that can fail. Since most monitors, unless they are very
expensive and high end models, they are designed to not be serviced.
In the low to medium end monitors, many of the manufactures don't sell
the parts for out of warranty servicing.

I'm asuming that my Eizo monitor is one of high quality, so I expect to use
it for a while. With the color restoration feature, the brightness should
even stay constant.

BTW, do you know something about that color restoration feature? I may have
some troubles with it.

Enjoy the monitor. The way things are going obsolete these days, in a
few years, your monitor will be useless, and may have to be changed
anyways.

I hate that aspect of modern economy. Devices are designed to fail after a
few years, so the manufacturer will sell more...

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[Andy Cuffe]

Halfgaar wrote:

I'm asuming that my Eizo monitor is one of high quality, so I expect to use
it for a while. With the color restoration feature, the brightness should
even stay constant.

BTW, do you know something about that color restoration feature? I may have
some troubles with it.

Most recent Sony monitors have a feature called color restore that
appears to apply various preset signlas to the CRT and measures the
cathode currents so it can return them to the original factory preset
values. It's basically an automatic grayscale adjustment. It works so
well that I've been able to swap CRTs and only have to run the color
restore to get a perfect grayscale. It take a lot longer to complete
the color restore after a CRT swap, but it eventually gets it right.
--
Andy Cuffe
baltimora@psu.edu

 

[Halfgaar]

Andy Cuffe wrote:

Most recent Sony monitors have a feature called color restore that
appears to apply various preset signlas to the CRT and measures the
cathode currents so it can return them to the original factory preset
values. It's basically an automatic grayscale adjustment. It works so
well that I've been able to swap CRTs and only have to run the color
restore to get a perfect grayscale. It take a lot longer to complete
the color restore after a CRT swap, but it eventually gets it right.

Can you tell me this? My monitor, Eizo T766, Sony Triniton tube, displays a
grey square for a about a second and then returns to the OSD. I've tested a
lot of them, and this is what they do. Except for two exceptions
(reasonably new models, newer than mine), which noticibly changes RGB
intensity for a while, after displaying the grey square. They do that every
time again. So my monitor, and many others, appear to be doing nothing at
all. Or, the only thing I can think of, is that by displaying that grey
square, it determines that the CRT is still OK and does not have to be
adjusted. So in essence, those two models I've seen which do calibrate
wouble become the faulty ones, not mine. Any comments on this?

Eizo instisted that it should behave like my T766 does. But companies will
say anything to protect themselves.

Halfgaar
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[Andy Cuffe]

Halfgaar wrote:

Can you tell me this? My monitor, Eizo T766, Sony Triniton tube, displays a
grey square for a about a second and then returns to the OSD. I've tested a
lot of them, and this is what they do. Except for two exceptions
(reasonably new models, newer than mine), which noticibly changes RGB
intensity for a while, after displaying the grey square. They do that every
time again. So my monitor, and many others, appear to be doing nothing at
all. Or, the only thing I can think of, is that by displaying that grey
square, it determines that the CRT is still OK and does not have to be
adjusted. So in essence, those two models I've seen which do calibrate
wouble become the faulty ones, not mine. Any comments on this?

Eizo instisted that it should behave like my T766 does. But companies will
say anything to protect themselves.

Halfgaar
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I'm not familiar with Eizo monitors, but it you could be right. What
happens when you try to run it a second time on the ones that seemed to
do a calibration?
--
Andy Cuffe
baltimora@psu.edu

 

[Halfgaar]

I'm not familiar with Eizo monitors, but it you could be right. What
happens when you try to run it a second time on the ones that seemed to
do a calibration?

As I said, they do that every time again (calibrate RGB), but there's
something to tell about that.

I've borrowed a T965 for a week or so from the repairservicecenter. That one
recalibrated red/green/blue time and time again. I also tested one which
was on display in a shop. I believe I tried it on that one twice, and both
times it calibrated RGB. The odd thing is, when I tried it a week or two
later, it did as mine, display only a grey square for about a second.

Then the last one: I asked someone I know of an internet-forum who has the
same monitor to describe what happens. His monitor also calibrated RGB.
But, I didn't ask him to do it a second time. Perhaps I could do that.

But is the colorrestoration feature of monitors based on the same tube so
different? I mean, it utilizes a feature of the tube, right? What did the
Sony tubes display you have experience with?

Halfgaar
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