dimitris <dimitris@some.server.edu.au> writes:
>I have a 20D10 monitor hooked to Ultra2 which seems to be a bit ill.
>Every time I switch off the monitor, for a second or two after I press
>the switch button, I see some dancing, colorful dots, around the center
>of the screen. This effect seems to be getting brighter over time. Other
>than that, the monitor seems fine - no visible distortions of the
>picture. Should I start planning of getting a new monitor? Is there
>something that I could check? I am no monitor expert but I could replace
>a capacitor if that's what causes the problem.
This sounds quite normal. It's caused by the drive to the colour guns and
the electron beam deflection coils, and the EHT drive to the anode of the
tube, all decaying after power is removed and whatever charge is left over
in those parts of the circuit will drop away producing unpredictable signals
as the charge dies away.
Despite what other people might say, you should actually never turn off a
CRT monitor if you want it to have a long life. Electrical cycling produces
thermal cycling and that is the biggest source of failure in any high-power
electronic device. CRT monitors use a *lot* of electricity so all that
electrical energy generates a large amount of heat as the electrical energy
is expended to manipulate the electron beams which create the image you see
on the front of the screen.
Of course it may not be practical to leave a monitor turned on all the time
(such as if the large amount of heat will cause problems with something
else, or just run up a big power bill), but in general leaving it turned on,
especially when the monitor has a 'standby' mode in the absence of a video
signal, helps prolong it's life.
Regards,
Craig.
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