48 Tubes for all Nations
Description
This article is from the comp.sys.ibm.pc.hardware.video Frequently Asked Questions, by Michael Scott with numerous contributions by others. (v1.0).
48 Tubes for all Nations
[From: Jeroen Stessen, Philips TV-lab Eindhoven NL ]
CRT Manufacturers actually make different versions of their tubes for TV's for the northern and southern hemisphere, and sometimes a 3rd neutral type. These are so-to-say precorrected for the uncompensated field. (Note that the term 'tube' here includes much of the convergence hardware as well - not just what is inside the glass.)
I remember when we exported projection televisions from Belgium to Australia, a couple of years ago. They all had to be opened on arrival to re-adjust the rotation settings on the convergence panel, due to the different magnetic field in Australia. Projection TV's don't have degaussing (there is nothing to degauss), and the customer can only adjust red and blue shift, not rotation.
Our CRT application group has a "magnetic cage". This is a wooden cube (approx. 2 meter long sides) with copper coils around each of the 6 surfaces. With this they can simulate the earth magnetic field for every place on earth (as indicated on a map on the wall).
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