🚀 go-pugleaf

In article <5v6ad4$l7v@lztnsc06.att.com>,
news_check.py <ltest@rte9-sun_5.5.1> wrote:
:In article <5v4683$h29@acme.sb.west.net> jay@west.net (Jay Hennigan) wrote:
:> Mike Coughlin (mikc@gnu.ai.mit.edu) wrote:
:> : In article <5u15eh$q4e@janis.virago.org.au>,
:> : Rachel Polanskis <r.polanskis@nepean.uws.edu.au,grove@zeta.org.au> wrote:

:Mike Coughlin (mikc@gnu.ai.mit.edu) wrote:
:: In article <5u15eh$q4e@janis.virago.org.au>,
:: Rachel Polanskis <r.polanskis@nepean.uws.edu.au,grove@zeta.org.au> wrote:
 
:: >I have heard that monitors for distribution in the Northern Hemisphere
:: >are different to monitors in the Southern Hemisphere.
 
::     The monitors are exactly the same. They are only adjusted
:: differently.
 
::     The electron beam which creates the display in the tube must
:: be exactly adjusted so all three colors (red, green and blue) are 
:: the same size and in the same position all over the screen. The 
:: earth's magnetic field effects this. The direction of the field
:: is opposite in the Northern and Southern hemispheres. So a color
:: monitor adjusted properly in the United States will be out of
:: adjustment in Australia. 

:This doesn't make sense.  The same difference in magnetic field will 
:result from turning a monitor with the screen facing north to the screen 
:facing south (or east to west) in the same geographic location.  

    You are thinking that the Earth's magnetic field is only
two dimensional. But it is three dimensional. The horizontal
components will act the same way in the Northern and Southern
hemispheres, and color monitors are designed and shielded to
minimize this effect. But the vertical component of the field
will be opposite in the two hemispheres, and can change the
alignment when the monitor is moved over large distances in the
north south direction.

    Color monitors and TV sets that have instructions for
alignment (not provided for any Sun monitors) always say you
should put the CRT in a north south direction while making
these adjustments.  If you did the alignment with the CRT
facing east, then you would have maximum errors produced by
the Earth's magnetic field when you faced the CRT west.

-- 
   Michael Coughlin      mikc@gnu.ai.mit.edu      Cambridge, MA USA