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?