My magnetic compass is largely dominated by the earth's magnetic field
and not the local power lines. Why should you be surprised that it is
the same for a computer monitor?

/Bevin


David Knisely wrote:
Sally wrote:

The effect is real enough, and just to satisfy myself I just tried
rotating
both monitors in here by 90 degs.


The effect may be real, but the cause may not be the Earth's magnetic
field. To determine this, take your monitor out into a vacant lot away
from local power sources or local concentrations of metal (it will
require a generator or a long electrical cord), and then do the
rotation. Again, I don't see any such effect with either my 27 inch CRT
TV, my 19 inch computer monitor, or my 13 inch color set. Its local
fields from magnets in motors or DC currents in lines which may make the
difference.

Take a look at:
http://www.anatekcorp.com/smask.htm
This article is written by a Philips Engineer and goes into some detail
about the interaction between the crt shadow mask, the earth's magnetic
field and colour purity. He seems to be convinced that the effect is real


Well, again, the article says something which might not be the full
effect. Again, I don't see much of a change in the performance of my
monitor when I move it from place to place or rotate it.