> There is a noise of about 15Khz. When I drop down the 
> resolution to 800x600
> the noise stops.
> As well as 1 hour after switched on.
>
> Brigth is at maximum,

Just as a possible add on to the other suggestions.
Most CRT HV units have a non user-adjustable focus 
adjustment knob on them and some have two knobs with the 
second altering brightness by altering voltage.

In old monitors, adjusting the focus control is usually 
beneficial. Adjusting the brightness control to bring the 
usual adjustment pot back from its maximum position and/or 
give you more brightness is also often useful.

it *MAY* be that, if the latter option is available in your 
case, that it will also affect the sound output that you 
mention, as eg the load offered by the pot may be reduced. 
May well not help but arguably worth trying.

In situations where the above help the monitor is usually 
well on its way to dying and these are stop-gap measures 
which may give it slightly more life.



        Russell


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