Re: Apple RGB Monitor Making Very High P

[antares@delphi.com (Leonard Lanigan)]

The high pitched noise is caused by the horizontal scan circuitry. The
frequency of the sound is 15,750 Hz just as it is from a TV set, which uses
the same horizontal scan freq. 

Generally the sound is the result of vibrating laminations in the horizontal
flyback transformer, which is audible to many women and youngsters
(fortunately, or perhaps not, in my mid 40's I still hear it, often to my
annoyance). 

Sometimes the sound resonates with something in the cabinet and amplifies the
sound, making it audible from considerable distances (I can tell if a monitor
is left on in a school Apple II computer lab just by that sound). You might
have a technician check to see if the transformer laminations are held
together with nuts and bolts, which can be tightened (as is sometimes the
case), or if there is some other mechanical way to subdue the noise. Failing
that, a new flyback may help. But the noise is real and can be most irksome to 
those who hear it. 

Regards,

Leonard Lanigan (ANTARES@delphi.com)