CRT monitor getting brighter over time

[Wiebe Cazemier]

Hi,

My Eizo T766 CRT monitor has been turning brighter for years, ever since I got
it. I used to be able to correct it using the cut-off and gain controls in the
on screen menu, but the red had reached 0%, so I was out of lee-way.
Therefore, I resorted to adjusting the flyback transformer.

Anyway, my question is, what could be causing a monitor to turn brighter? Every
other monitor I know turns darker over time.

And on a sidenote, when calibrating the flyback transformer, what voltage is it
you're adjusting? Acceleration voltage?

Regards,

Wiebe Cazemier

 

[JANA]

The adjustment on the HV multiplier is the G2 or screen grid voltage. In
actual fact, it must be within a specific spec range. The tube bias settings
must be set to make the cut-off for each colour-gun in the tube properly
track and work within proper range. On most monitors manufactured after
1994, most of these settings are done through a specific service set-up and
manufacture software using their dedicated hardware interface for the
particular monitor.

Obviously some component or device is going defective, thus causing the
brightness to be changed. Many times, I found the HV multiplier to be the
fault. Sometimes, it has been other types of components in the bias and
drive circuits that work with the CRT.

If there is adequate range, you can try to turn down the G2 bias on the HV
module. This will only be a temporary fix. The characteristics of the colour
tracking and the black cut-off levels will be most likely be changed when
this control is adjusted.

I would be seriously considering to get a new LCD panel at this point. You
will find it superior to an old CRT monitor.

--

JANA
_____


Hi,

My Eizo T766 CRT monitor has been turning brighter for years, ever since I
got
it. I used to be able to correct it using the cut-off and gain controls in
the
on screen menu, but the red had reached 0%, so I was out of lee-way.
Therefore, I resorted to adjusting the flyback transformer.

Anyway, my question is, what could be causing a monitor to turn brighter?
Every
other monitor I know turns darker over time.

And on a sidenote, when calibrating the flyback transformer, what voltage is
it
you're adjusting? Acceleration voltage?

Regards,

Wiebe Cazemier

 

[[email protected]]

You need to run the color restoration as shown on page 16 of the user
manual.
The monitor must be on for a minimum of 60 minutes, no screen saver or
power save mode, in order for this option to come up.
This will compensate for the wear on the picture tube if you did not
wait too long to run it.

http://www.eizo-downloads.com/downloads/manuals/index.php

 

[Wiebe Cazemier]

You need to run the color restoration as shown on page 16 of the user
manual.
The monitor must be on for a minimum of 60 minutes, no screen saver or
power save mode, in order for this option to come up.
This will compensate for the wear on the picture tube if you did not
wait too long to run it.

http://www.eizo-downloads.com/downloads/manuals/index.php

Do you think I would know how to adjust the flyback transformer but not know
about this feature... ? It didn't compensate for the overly bright image.

 

[Wiebe Cazemier]

The adjustment on the HV multiplier is the G2 or screen grid voltage. In
actual fact, it must be within a specific spec range. The tube bias settings
must be set to make the cut-off for each colour-gun in the tube properly
track and work within proper range. On most monitors manufactured after
1994, most of these settings are done through a specific service set-up and
manufacture software using their dedicated hardware interface for the
particular monitor.

Obviously some component or device is going defective, thus causing the
brightness to be changed. Many times, I found the HV multiplier to be the
fault. Sometimes, it has been other types of components in the bias and
drive circuits that work with the CRT.

If there is adequate range, you can try to turn down the G2 bias on the HV
module. This will only be a temporary fix. The characteristics of the colour
tracking and the black cut-off levels will be most likely be changed when
this control is adjusted.

I had already changed the bias on the HV module. When I did so, the image
looked somewhat bluish. I ran the the automatic color restoration feature,
which dkuhajda mentioned, and everything was corrected. The reference image I
created to calibrate cut-off and gain of each individual color shows a perfect
image.

BTW, the automatic color restoration never seemed to have done anything in the
past. But after changing the HV bias, it did work (I could see it do things it
never did before).

BTW2, I don't think some component is going bad. It's not as if it started
doing this suddenly. In the course of the 4 years that I've had it, it slowly
turned brighter.

Also, the HV bias is very touchy. When I turned it down just a tad without
looking at the screen, it went completely black. Could it be possible that for
some reason, like heat contraction/expansion, the HV bias control changed
gradually?

I would be seriously considering to get a new LCD panel at this point. You
will find it superior to an old CRT monitor.

This is the last 19" CRT Made by Eizo, using a Sony Trinitron apature grill
tube; it's one of the best CRT's out there. I bought it in 2003. And I find
the image quality far, far superior to any TFT I've seen. It still works
perfectly, besides the screen slowly getting brighter (which is fixed for
now).

I don't like TFT and I will never get one, if possible. I don't like the
concept of backlights, I don't like the concept of dithering 18 bit color to
produce 16.2 milion (not 16.7 as true 24 bit would be), I don't like native
resolutions inherent in low-DPI fixed pixel displays, etc.

 

[James Sweet]

Do you think I would know how to adjust the flyback transformer but not
know
about this feature... ? It didn't compensate for the overly bright
image.

I didn't know my monitor had this feature until relatively recently, and I
had already been inside it searching for a screen adjustment on the flyback.
Ended up needing the Sony DAS software to get everything where it should be
though.

 

[Jamie]

I had already changed the bias on the HV module. When I did so, the image
looked somewhat bluish. I ran the the automatic color restoration feature,
which dkuhajda mentioned, and everything was corrected. The reference image I
created to calibrate cut-off and gain of each individual color shows a perfect
image.

BTW, the automatic color restoration never seemed to have done anything in the
past. But after changing the HV bias, it did work (I could see it do things it
never did before).

BTW2, I don't think some component is going bad. It's not as if it started
doing this suddenly. In the course of the 4 years that I've had it, it slowly
turned brighter.

Also, the HV bias is very touchy. When I turned it down just a tad without
looking at the screen, it went completely black. Could it be possible that for
some reason, like heat contraction/expansion, the HV bias control changed
gradually?




This is the last 19" CRT Made by Eizo, using a Sony Trinitron apature grill
tube; it's one of the best CRT's out there. I bought it in 2003. And I find
the image quality far, far superior to any TFT I've seen. It still works
perfectly, besides the screen slowly getting brighter (which is fixed for
now).

I don't like TFT and I will never get one, if possible. I don't like the
concept of backlights, I don't like the concept of dithering 18 bit color to
produce 16.2 milion (not 16.7 as true 24 bit would be), I don't like native
resolutions inherent in low-DPI fixed pixel displays, etc.

Don't you get it?

It's not what you like and what you want!

It's what they want you to have and you will like it. You

will have one regardless the price they dictate and pay it!

And wait, that's not all. After you are forced into giving them
your money for something you don't want. It'll be obsolete just after
you walk out the store and repairs will be many times more than just
going though the same ordeal again which they will so condition you
to adhere too!

Btw.
Have a great Xmas!

 

[Wiebe Cazemier]

I didn't know my monitor had this feature until relatively recently, and I
had already been inside it searching for a screen adjustment on the flyback.
Ended up needing the Sony DAS software to get everything where it should be
though.

You needed the Sony software after the adjustment on the flyback?

 

[Wiebe Cazemier]

Don't you get it?

It's not what you like and what you want!

It's what they want you to have and you will like it. You

will have one regardless the price they dictate and pay it!

And wait, that's not all. After you are forced into giving them
your money for something you don't want. It'll be obsolete just after
you walk out the store and repairs will be many times more than just
going though the same ordeal again which they will so condition you
to adhere too!

Sadly, you are correct. The industry needed something new. And unfortunately,
most people want these TFT screens because of their small size. The real
high-end user has to suffer for the ignorance of the masses. It amazes me how
much effect the appearance of the actual machine has on the quality of the
screen, for most people. I could write an entire essay about that subject...

Luckily, these Eizo screens are made to last. With the calibration features it
offers, the picture's is as good as new after 14608 hours of use. A low-end
monitor would almost have reached its MTBF by now...

With some luck, SED screens are available when this monitor dies. The
technology exists, but there are license issues. SED is still a fixed pixel
grid, but at least works on the basis of color addition (like your eyes!) as
opposed to color polarization and subtraction.

BTW, I just watched some DVD on this screen. The absolute blackness this
monitor offers is SO important for the image quality. As soon as the slightest
bit of grey starts to leak through, the entire image quality suffers; it just
looses its feel. It's as if you throw a bucket of paint over a Van Gogh... I
always compare backlight bleeding to noise in audio. For some reason, people
dispise the latter, but accept the former...

Btw.
Have a great Xmas!

Same to you. Bet you got a TFT screen for christmas

 

[James Sweet]

You needed the Sony software after the adjustment on the flyback?

There is no adjustment on the flyback, or any other internal controls. It's
all done by software.

 

[Jerry G.]

When I used to service monitors, I changed many of these HV multipliers
to correct the fault you are describing. In most monitors it is part of
the flyback assembly. On the odd occasion, I have had CRT's starting to
go defective to also cause this problem.

Personally, I would consider changing the monitor for a good LCD type.
Then you will be good for a number of years without any problems.

--

Jerry G.

The adjustment on the HV multiplier is the G2 or screen grid voltage.
In
actual fact, it must be within a specific spec range. The tube bias
settings
must be set to make the cut-off for each colour-gun in the tube
properly
track and work within proper range. On most monitors manufactured
after
1994, most of these settings are done through a specific service
set-up and
manufacture software using their dedicated hardware interface for the
particular monitor.

Obviously some component or device is going defective, thus causing
the
brightness to be changed. Many times, I found the HV multiplier to be
the
fault. Sometimes, it has been other types of components in the bias
and
drive circuits that work with the CRT.

If there is adequate range, you can try to turn down the G2 bias on
the HV
module. This will only be a temporary fix. The characteristics of the
colour
tracking and the black cut-off levels will be most likely be changed
when
this control is adjusted.

I had already changed the bias on the HV module. When I did so, the
image
looked somewhat bluish. I ran the the automatic color restoration
feature,
which dkuhajda mentioned, and everything was corrected. The reference
image I
created to calibrate cut-off and gain of each individual color shows a
perfect
image.

BTW, the automatic color restoration never seemed to have done anything
in the
past. But after changing the HV bias, it did work (I could see it do
things it
never did before).

BTW2, I don't think some component is going bad. It's not as if it
started
doing this suddenly. In the course of the 4 years that I've had it, it
slowly
turned brighter.

Also, the HV bias is very touchy. When I turned it down just a tad
without
looking at the screen, it went completely black. Could it be possible
that for
some reason, like heat contraction/expansion, the HV bias control
changed
gradually?

I would be seriously considering to get a new LCD panel at this point.
You
will find it superior to an old CRT monitor.

This is the last 19" CRT Made by Eizo, using a Sony Trinitron apature
grill
tube; it's one of the best CRT's out there. I bought it in 2003. And I
find
the image quality far, far superior to any TFT I've seen. It still works
perfectly, besides the screen slowly getting brighter (which is fixed
for
now).

I don't like TFT and I will never get one, if possible. I don't like the
concept of backlights, I don't like the concept of dithering 18 bit
color to
produce 16.2 milion (not 16.7 as true 24 bit would be), I don't like
native
resolutions inherent in low-DPI fixed pixel displays, etc.

 

[Wiebe Cazemier]

When I used to service monitors, I changed many of these HV multipliers
to correct the fault you are describing. In most monitors it is part of
the flyback assembly. On the odd occasion, I have had CRT's starting to
go defective to also cause this problem.

In these monitors, what exactly is going bad? The HV multiplier is nothing but
a bunch of copperwire wrapped around some core, right? How can that wear
down...?

Personally, I would consider changing the monitor for a good LCD type.
Then you will be good for a number of years without any problems.

No flame intended, but I really don't understand why people are advising me to
get a new TFT screen. The issue I described is a very minor. The drift has
been so slow that every few months the colors needed a bit of calibration. The
colors are still extremely pure, black is pitch black, white is brightly
white, the image is sharp, high voltage regulation is perfect (so the image is
stable under all brightness conditions, RGB convergence is good, etc. In other
words, it displays a perfect picture.

Even if you didn't dispise TFT's like I do (see my other posts), you would be
mad to replace this screen only because the HV bias needed a minor
adjustment... If it were 10 or 15 years old, perhaps there would be some logic
to it, but after 4 years of use and the MTBF not reached by a long shot...?

 

[Wiebe Cazemier]

There is no adjustment on the flyback, or any other internal controls. It's
all done by software.

I thought all flybacks had adjustment controls nowadays. I guess then I'm lucky
this monitor still had them, seeing as how it's the most modern CRT every
made.

 

[William Sommerwerck]

In these monitors, what exactly is going bad? The HV multiplier is
nothing but a bunch of copper[ ]wire wrapped around some core,
right? How can that wear down...?

You're confusing voltage multipliers with transformers.

 

[William Sommerwerck]

Luckily, these Eizo screens are made to last. With the calibration
features it offers, the picture's is as good as new after 14608 hours
of use. A low-end monitor would almost have reached its MTBF by
now...

Is a ViewSonic a low-end monitor? Mine is about 5 years old, gets two to
three hours' (at least) use each day, and is running fine. I have no
intention of buying an LCD display until this monitor fails (or I buy my
next computer).

There was a time when Eizo was pretty much _the_ monitor to own. It is not
longer a highly visible brand, at least not in the US.

With some luck, SED screens are available when this monitor dies.
The technology exists, but there are license issues.

The current consensus is that the license issues will not be resolved and we
will never see SED displays.

I've wondered why we haven't seen much in the plasma-based computer
displays. I can think of a number of reasons, including limited resolution
for a given screen size and significantly higher power consumption.

SED is still a fixed pixel grid, but at least works on the basis of color
addition (like your eyes!) as opposed to color polarization and

subtraction.

Way incorrect.

All current LCDs use additive color. Some years back there were LCD panels
for transparencey projectors that used subtractive synthesis. This allowed
significantly higher resolution, but had no other advantage I can think of.

If you want to get picky about it, subtractive systems are "additive" in
that (for example) the yellow layer -- and only the yellow layer -- controls
the amount of blue light in the image. The blue light passed by the yellow
layer is "added" to the green light passed by the magenta layer and the red
light passed by the cyan layer. (This is all semantics, of course. I'm
making a point, not trying to "prove" something.)

I have no idea what you mean by "color polarization". The polarized layers
in an LCD are _not_ used to create colors (such as the colors seen when
placing plastics between crossed polarizers).

 

[jango2]

Anyway, my question is, what could be causing a monitor to turn brighter? Every

other monitor I know turns darker over time.

Defective 200V line electrolytic filter capacitor?.
Reduced capacitance due to drying electrolyte.
Doesn't charge to 180 or 200 volts anymore causing lower cathode
voltages thereby driving beam current up.
Usually a 22uF/250V.
Merry Xmas
Jango

 

[Wiebe Cazemier]

Is a ViewSonic a low-end monitor? Mine is about 5 years old, gets two to
three hours' (at least) use each day, and is running fine. I have no
intention of buying an LCD display until this monitor fails (or I buy my
next computer).

I don't know much about ViewSonic. It's not, or hardly, available here. But
with low-end, I meant the cheapest models. I have a Philips 105S here, which
is one of those. Image quality has degraded significantly over the three years
I used it.

This Eizo monitor has been running about 12 hours per day or more (I work at
home) for the last few years. The hours of use I mentioned can be found in the
OSD menu.

There was a time when Eizo was pretty much _the_ monitor to own. It is not
longer a highly visible brand, at least not in the US.

I would agree. Their TFT screens are no better than others I've seen. As for
CRT, it's a long story, but I tried several T766 models and this one was the
only one without grave convergence errors. Philips high-end CRT range also
suffered from major convergence problems (I had tried 6 different 109p40's
before giving up and going for this Eizo...).

But, now that I have this specific one, I'm glad I have it. It still has
the "Eizo Legacy" of quality... Not just in image quality, but also in
features. I've never seen another monitor which allows you to set the color
cut-off in the OSD menu, for example. It could be that there are, but I've
never seen one

I've wondered why we haven't seen much in the plasma-based computer
displays. I can think of a number of reasons, including limited resolution
for a given screen size and significantly higher power consumption.

Don't plasma screens wear down very rapidly? Computerscreens are used more than
TV's, mostly, so perhaps that's the reason? Or, more likely, they want to
exploit the investments made for TFT as much as possible. It's better for them
to wait with the introduction of a new technology.

Way incorrect.

All current LCDs use additive color. Some years back there were LCD panels
for transparencey projectors that used subtractive synthesis. This allowed
significantly higher resolution, but had no other advantage I can think of.

If you want to get picky about it, subtractive systems are "additive" in
that (for example) the yellow layer -- and only the yellow layer -- controls
the amount of blue light in the image. The blue light passed by the yellow
layer is "added" to the green light passed by the magenta layer and the red
light passed by the cyan layer. (This is all semantics, of course. I'm
making a point, not trying to "prove" something.)

I have no idea what you mean by "color polarization". The polarized layers
in an LCD are _not_ used to create colors (such as the colors seen when
placing plastics between crossed polarizers).

As it says at [1]: "LCD technology is based on the properties of polarized
light (...) When an LCD pixel darkens, it polarizes at 90 degrees to the
polarizing screens.". However, it could be that I've got stuff mixed up. I do
know that wearing polarized sunglassed can make an LCD display (like on a
watch) unreadable, but I've never tried it on a TFT LCD screen.

As for the subtraction; the process of creating color in TFT screens starts
with white light, which is then turned into the desired color. I call that
subtraction. It may not be literal subtraction from the point of view of the
sub pixel, but I do think this idea is principally flawed. You cannot make
monochromatic light for the RGB colors that way. The phosphor photon-emission
of a CRT comes much closer, if not completely.

Anyway, you seem to know more about TFT screens that I do, but that doesn't
take away the fact that I don't like them . Image quality is just too poor,
and the manufacturers cheat to get higher specs, and those cheats are visible.

[1] http://en.wikipedia.org/wiki/Liquid_crystal_display_television

 

[Wiebe Cazemier]

Defective 200V line electrolytic filter capacitor?.
Reduced capacitance due to drying electrolyte.
Doesn't charge to 180 or 200 volts anymore causing lower cathode
voltages thereby driving beam current up.
Usually a 22uF/250V.
Merry Xmas
Jango

Drying electrolyte is consistent with the from-the-start slow increase in
brightness. Also, I've seen a lot of devices with leaking caps, so they are
quite notorious.

BTW, how exactly is the beam current driven up when the voltage decreases? I
would have expected it to be the other way around.

 

[William Sommerwerck]

As for the subtraction; the process of creating color in TFT screens starts
with white light, which is then turned into the desired color. I call that
subtraction.

Not in the usual sense. LCDs work by "adding" individual R, G, and B pixels.
A true subtractive panel would have cyan, magenta, and yellow layers.

It may not be literal subtraction from the point of view of the sub-
pixel, but I do think this idea is principally flawed. You cannot make
monochromatic light for the RGB colors that way. The phosphor
photon-emission of a CRT comes much closer, if not completely.

Phosphors aren't monochromatic, either.

 

[James Sweet]

Is a ViewSonic a low-end monitor? Mine is about 5 years old, gets two to
three hours' (at least) use each day, and is running fine. I have no
intention of buying an LCD display until this monitor fails (or I buy my
next computer).

There was a time when Eizo was pretty much _the_ monitor to own. It is not
longer a highly visible brand, at least not in the US.

Viewsonic is a mid range monitor, I've had a few of them and they provide
good performance for the price, but there's better monitors out there. Some
models were very prone to failure, I replaced at least half a dozen
optocouplers in the power supplies, they would fail slowly and cause the
voltage to creep up until it blew the vertical output IC.

Eizo monitors are really excellent. I recently repaired a 14 year old Nanao
(former name of Eizo) monitor my mom has, a few new capacitors and it has a
razor sharp image, it's still perfectly serviceable.

TFT monitors are good for laptops, and anywhere space is critical, I have a
nice big one at work which does look pretty good, but the flat Sony CRT I
have at home is far superior to my eyes.