Since it is not one colour that is changing brightness, the fault is common
to all three. There is a part in the brightness bias circuits, or CRT bias
circuits, or the HV multiplier that has become thermo sensitive with age.
You will have to take measurements during the coarse of the problem, in
order to determine the failed area to begin with.

Many times, have seen capacitors become thermo sensitive. Also, there is a
strong possibility that the HV multiplier is defective.

I guess you know now, why the previous owner sold his monitor! I myself read
many cases where people buy used equipment, and it is very rare that there
is one that is in perfect working order.

--

Jerry G.
=====

wrote in message
oups.com...
Hello, i bought a used Dell P1110 monitor with a somewhat odd problem.
When it is cold, it has the notorious overbrightness problem (zero on
the brightness looks like normal brightness). BUT... as it warms up, it
slowly returns to normal brightness (~15 to 20 minutes and 30 to 35 on
the brightness looks normal). I have tried the "color return" feature
which helped a little bit, but not enough. Am i correct in assuming
that the resistor fix for the overbrightness problem will not work in
this case (will it make it normal brightness when cold but too dark
when warmed up)? What could be causing this and how can i fix it?
Thanks.