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PCBUILD - Personal Computer Hardware discussion List <[log in to unmask]>
Date:
Fri, 28 Jul 2000 13:37:17 -0700
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On Thu, 27 Jul 2000 Dean Kukral wrote:

>  .... a question appeared ....
>  It asked whether PC monitors worked
>  differently in the North and South hemispheres.
>
>  The reply included, "Yes, images on a monitor
>  designed to work in one hemisphere will look
>  slightly different when viewed in the other."
>  It went on to attribute this to the Earth's magnetic
>  field and cited John Hall of Acer Peripherals.
>
I'm not a expert, but have tv repair experience. My understanding tells me
there will be no difference.

the reason is:  The electron beam originating in the cathode of pix tube and
enroute to anode (pix tube face where pixels are located), passes through a
yoke which is controled by a sawtooth voltage.  This linear voltage through
the yoke coil creates a magnetic field which influences the horizonital
sweep. A second part of the yoke coil controls the vertical sweep.  Hence,
if all is well, you have a raster or a white screen.  Your eye is not fast
enough to see the electron dot that starts in the left hand corner of the
pix tube and makes lines from top to botton to create a raster. no outside
force can change those sweep voltages and magnetic fields unless the
physical parts are tampered with such as moving the position of the yoke,
ect.

But external magnetic fields can create colors on the screen. In the old
days we made easy money by demagnetising a pix tube when someone turned off
a vac cleaner near the tv.  Later, the manufacturers included a internal
degaussing coil and that killed the goose.
 If you look inside your monitor you can see the same degauss coil circling
the front of the pix tube. You can also see the yoke.  And by the way, it is
not "sudden death" to look inside your monitor.  But be careful where you
put your hands if you have a bad heart or are standing in a bathtub.

If the earth's magnetic field can influence the screen I would welcome the
electron theory explanation

mike michel
>
>





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