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NotTaR of Television Sets : B/W TV size, position, and geometry adju..
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1994-2007, Samuel M. Goldwasser. All Rights Reserved. Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied: 1. This notice is included in its entirety at the beginning. 2. There is no charge except to cover the costs of copying.
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These tend to be a lot simpler and less critical than for color monitors
or TV sets.
On a B/W TV you will probably see some of the following adjustments:
- Position - a pair of rings with tabs on the neck of the CRT.
There may be electronic position adjustements as well though this
is not that common on small TVs.
- Width and height (possibly linearity as well) controls. There may be
some interaction between size and linearity - a crosshatch test pattern
is best for this. Vertical adjustments are almost always pots while
horizontal (if they exist) may be pots and/or coils. Size will normally
be set for 5-10% overscan to account for line voltage fluctuations and
component drift. Confirm aspect ratio with test pattern which includes
square boxes.
- Geometry - some little magnets either on swivels around the yoke or
glued to the CRT. If these shifted, the the edges may have gotten
messed up - wiggles, dips, concave or convex shapes. There may be
a doxen or more each mostly affecting a region around the edge of the
raster. However, they will not be totally independent.
Check at extremes of brightness/contrast as there may be some slight
changes in size and position due to imperfect HV regulation.
There may be others as well but without a service manual, there is no
way of knowing for sure. Sams' often has folders for B/W TVs.
Just mark everything carefully before changing - then you will be able to
get back where you started.
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