Magnetised CRT
 

I have a Goodmans 19" (I think) CRT TV which is used mainly for gaming
(Xbox). If very light colours are displayed on it for much more that a
minute, the purity will start to degrade. Let's say a racing game is being
played, the car takes up most of the screen, and is light silver. After
about a minute, the right of the car will be pink and the left will be
green. This would suggest that it's magnetised by some external source but
a similar thing happens to the 21" downstairs, but less extensively. It is
not all that noticeable on most games/programmes but I have just bought a
game that has almost entirely white menus and within a minute the menu is
half red half green. As soon as darker colours are displayed, the
distortion goes away. Also, if a very still image is displayed for a while,
the same thing happens, even with darker colours. Switching off, degaussing
and getting the image moving again all make it fade away, but only
temporally.
Any ideas?

Well the first obvious question is, are there any magnetic sources
near these sets? Speakers, other stereo or computer components
etc?

"Lewis" wrote in message ...
I have a Goodmans 19" (I think) CRT TV which is used mainly for gaming
(Xbox). If very light colours are displayed on it for much more that a
minute, the purity will start to degrade. Let's say a racing game is being
played, the car takes up most of the screen, and is light silver. After
about a minute, the right of the car will be pink and the left will be
green. This would suggest that it's magnetised by some external source but
a similar thing happens to the 21" downstairs, but less extensively. It is
not all that noticeable on most games/programmes but I have just bought a
game that has almost entirely white menus and within a minute the menu is
half red half green. As soon as darker colours are displayed, the
distortion goes away. Also, if a very still image is displayed for a while,
the same thing happens, even with darker colours. Switching off, degaussing
and getting the image moving again all make it fade away, but only
temporally.
Any ideas?

This makes me think that you may have some unshielded or poorly shielded
speakers sufficiently close to the CTR to influence it. If you're using some
external speakers try placing them away from the monitor. If the internal
speakers are doing this... I had a 27" Samsung once that use to do that. I
took it apart got rid of throw those speakers and install new ones with a
better magnetic shield. They happened to be exactly like the speakers I
collected from one of those computer monitors with speakers inside....


....sm


"Lewis" wrote in message
...
I have a Goodmans 19" (I think) CRT TV which is used mainly for gaming
(Xbox). If very light colours are displayed on it for much more that a
minute, the purity will start to degrade. Let's say a racing game is
being
played, the car takes up most of the screen, and is light silver. After
about a minute, the right of the car will be pink and the left will be
green. This would suggest that it's magnetised by some external source
but
a similar thing happens to the 21" downstairs, but less extensively. It
is
not all that noticeable on most games/programmes but I have just bought a
game that has almost entirely white menus and within a minute the menu is
half red half green. As soon as darker colours are displayed, the
distortion goes away. Also, if a very still image is displayed for a
while,
the same thing happens, even with darker colours. Switching off,
degaussing
and getting the image moving again all make it fade away, but only
temporally.
Any ideas?

"Main Account" writes:

This makes me think that you may have some unshielded or poorly shielded
speakers sufficiently close to the CTR to influence it. If you're using some
external speakers try placing them away from the monitor. If the internal
speakers are doing this... I had a 27" Samsung once that use to do that. I
took it apart got rid of throw those speakers and install new ones with a
better magnetic shield. They happened to be exactly like the speakers I
collected from one of those computer monitors with speakers inside....

If it's only light (bright) colors, I'd lean more towards doming - heating
of the shadowmask causing local changes in purity. Turn down the brightness.

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...sm


"Lewis" wrote in message
...
I have a Goodmans 19" (I think) CRT TV which is used mainly for gaming
(Xbox). If very light colours are displayed on it for much more that a
minute, the purity will start to degrade. Let's say a racing game is
being
played, the car takes up most of the screen, and is light silver. After
about a minute, the right of the car will be pink and the left will be
green. This would suggest that it's magnetised by some external source
but
a similar thing happens to the 21" downstairs, but less extensively. It
is
not all that noticeable on most games/programmes but I have just bought a
game that has almost entirely white menus and within a minute the menu is
half red half green. As soon as darker colours are displayed, the
distortion goes away. Also, if a very still image is displayed for a
while,
the same thing happens, even with darker colours. Switching off,
degaussing
and getting the image moving again all make it fade away, but only
temporally.
Any ideas?

On Sun, 22 May 2005 17:44:43 +0000 (UTC), "Lewis"
wrote:

I have a Goodmans 19" (I think) CRT TV which is used mainly for gaming
(Xbox). If very light colours are displayed on it for much more that a
minute, the purity will start to degrade. Let's say a racing game is being
played, the car takes up most of the screen, and is light silver. After
about a minute, the right of the car will be pink and the left will be
green. This would suggest that it's magnetised by some external source but
a similar thing happens to the 21" downstairs, but less extensively. It is
not all that noticeable on most games/programmes but I have just bought a
game that has almost entirely white menus and within a minute the menu is
half red half green. As soon as darker colours are displayed, the
distortion goes away. Also, if a very still image is displayed for a while,
the same thing happens, even with darker colours. Switching off, degaussing
and getting the image moving again all make it fade away, but only
temporally.
Any ideas?

well it sure is NOT magnetisim, that would always pe present, i
suggest this could be shadow mask doming. This is localised distortion
of the shadow mask caused by the electron beam heating it.
see http://www.eio.com/repairfaq/REPAIR/...tml#CRTFAQ_027 for
more.

kev

Call some service shops and see if they remember how to set purity on
the older RCAs (some SFS were like that too). It invloves two identical
disk magnets and getting the CRT up to full operating temperature.

Other than that you could just turn the contrast down.

JURB

"Lewis" wrote in message
...
I have a Goodmans 19" (I think) CRT TV which is used mainly for gaming
(Xbox). If very light colours are displayed on it for much more that a
minute, the purity will start to degrade. Let's say a racing game is
being
played, the car takes up most of the screen, and is light silver. After
about a minute, the right of the car will be pink and the left will be
green. This would suggest that it's magnetised by some external source
but
a similar thing happens to the 21" downstairs, but less extensively. It
is
not all that noticeable on most games/programmes but I have just bought a
game that has almost entirely white menus and within a minute the menu is
half red half green. As soon as darker colours are displayed, the
distortion goes away. Also, if a very still image is displayed for a
while,
the same thing happens, even with darker colours. Switching off,
degaussing
and getting the image moving again all make it fade away, but only
temporally.
Any ideas?



Sounds like the shadow mask is doming, try turning down the contrast.

Hi again, sorry I've been away so long, the doming idea sounds about right
because when it displays dark colours it fades away again. I now remember
turning the contrast up hugely and brightness up a bit for Halo 2 as it was
very dark. I'll try putting it down a bit. Thanks for all the answers.


"James Sweet" wrote in message
news:VxRke.386$m%3.122@trnddc02...

"Lewis" wrote in message
...
I have a Goodmans 19" (I think) CRT TV which is used mainly for gaming
(Xbox). If very light colours are displayed on it for much more that a
minute, the purity will start to degrade. Let's say a racing game is
being
played, the car takes up most of the screen, and is light silver. After
about a minute, the right of the car will be pink and the left will be
green. This would suggest that it's magnetised by some external source
but
a similar thing happens to the 21" downstairs, but less extensively. It
is
not all that noticeable on most games/programmes but I have just bought
a
game that has almost entirely white menus and within a minute the menu
is
half red half green. As soon as darker colours are displayed, the
distortion goes away. Also, if a very still image is displayed for a
while,
the same thing happens, even with darker colours. Switching off,
degaussing
and getting the image moving again all make it fade away, but only
temporally.
Any ideas?



Sounds like the shadow mask is doming, try turning down the contrast.