Sally wrote:
"David Knisely" wrote in message
om...

You didn't read what I said. I used the word "significantly". I have
not seen such a monitor of that size (a computer monitor, *not* a TV),

I'm sorry David but I must disagree. The 16" monitor I'm using right now
will show significant misconvergence if it is rotated, this shows up as
color fringing, especially at the corners. The only way to restore the
convergence is to do a manual degauss in the new orientation.

Do you have speakers close to the monitor?

I'm not saying that a geomagnetic storm will have any direct effect. I'm
just saying that the earth's normal magnetic field is strong enough to
affect a TV or monitor picture.

Any magnetic field will affect TVs and monitors, the obvious question is
rather where is the threshold of "noticeable". Compare that threshold
with the maximum fluctuation of earth's magnetic field at your latitude.
Keep in mind the relatively small surface of your monitor and the small
angle of the field vector towards your screen.I dont have the values
handy, but I must agree with David that such effects cannot be visible
as a direct result of magnetic field fluctuations. Unless (probably) if
you have a 25" monitor directed toward heavens and you live in northern
Finland.

In fact, your case is specific as it suggests the the field can be so
curved that it can produce patterns on the screen. The curves would, in
fact appear very smooth on our everyday scales.

And yes, I agree that nearby speakers and other magnets can also have an
effect although I'm not aware of any special magnetic screening on any
domestic TV or monitor that I have seen. Many of them do have an
electrostatic screen that seems to be some sort of conductive graphite
coating. On the other hand components that emit magnetic fields, such as
such as loudspeakers and transformers, often do have casings that function
as magnetic screens. I think it would be quite difficult to magnetically
screen a wide angle TV CRT from the front, since all conventional magnetic
screens that I'm aware of contain iron or iron alloys. Maybe the CRT shadow
mask could double up as such a screen, which reminds me of ...

So, you do have speakers near the monitor. Nc, nc...

A child waved a magnet in front of our TV set to see the "pretty colors" and
it took months (dozens of switch-on degausses) for that TV to settle down
again. I think that in this case it was the shadow mask that got permanently
magnetised...or at least it got magnetised for a few months.

Your explanation is correct. Minor fluctuations from the TV itself and
the environment will eventually randomise the weak residual magnetism.

Ivan