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PURITY AND CONVERGENCE
ADJUSTMENT
.
CAUTION: The Convergence and Purity adjustments have been made at the factory. Readjustment should be
made only after picture tube or deflection yoke replacement, following the steps below:
PURITY ADJUSTMENT
1.
Demagnetize
the picture tube and receiver using an external
degaussing
coil. When replacing
picture tube or deflection
yoke,
mount
deflection
yoke
and
purity -
convergence
magnets assembly properly, see figures 1 and 4.
2,Turn Red and Blue guns off and provide only Green raster.
Rotate Screen control to fully counterclockwise.
Rotate Red
and Blue Bias controls fully counterclockwise.
Slowly rotate
Green Bias control clockwise to produce Green raster.
3, Loosen the screw holding the Deflection
Yoke and remove
the 3 Rubber Wedges,
and slide the Deflection
Yoke fully
frontward.
4. Rotate and spread the Tabs of the two Purity Magnets
to
center the vertical green belt in the picture screen.
The Purity
Magnets are also adjusted to obtain vertical centering
of the
raster.
5. SIOWIY slide the Deflection
Yoke backward
until a uniform
green screen is obtained.
6. Check the purity of the red and blue screens for uniformity,
turn
off other
colours
to check
this
(use bias
controls).
Readjust the yoke position if necessary
until all screens are
pure.
7. Adjust each Bias control and screen control to obtain white
raster. Refer to Gray Scale Adjustment.
If pan of the picture
screen
is coloured,
adjust
the
Deflection
Yoke
position
forward or backward slightly.
FOUR-POLE
MAGNET TABS
-'d
SIX- POLE
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TABS
Figure- 1. PURITY AND CONVERGENCE
MAGNETS
Adjust tabs angle to superimpose
blue and red vertical line
J
Adjust tabs together to
RED
+
I_
superimpose
red and
1---
~___
L/
blue horizontal line
BLUE
Figure- 2 BLUE AND RED LINE MOVEMENT
8. Tighten the mounting
screw of the Deflection
Yoke.
Adjust
Convergence
next.
CENTER CONVERGENCE
ADJUSTMENT
1. Use a dot crosshatch pattern signal.
2. Turn Red and Blue guns on and turn off Green gun. Adjust
the angle between the Tabs of the Four Pole Magnet
1and
2,and superimpose
the Red and Blue vertical
lines in the
center area of the picture screen, Refer to figure 2.
3, Keeping
the mutual
angle
of the Tabs
of the Four
Pole
Magnet turn them together to superimpose
the Blue and Red
horizontal lines in the center area of the picture screen. Refer
to figure 2.
4. Turn Green gun on and adjust Six Pole Magnet 3 and 4s that
the Green line superimposed
on the Red/Blue lines.
This is the same procedure used in steps 2 and 3.
Refer to figure 3.
OUTER AREA CONVERGENCE
ADJUSTMENT
Slightly loosen the screw holding the Deflection
Yoke.
Adjust
the Deflection Yoke to converge the detail in the outer area (left
side and right side) of the picture screen by orbital movement
of
the front
of the Yoke,
then
secure
the
Deflection
Yoke
in
appropriate
position
by putting
the
wedges
as
illustrated.
Tighten screw holding the Deflection Yoke.
DEFLECTION
YOKE
Figure- 4. ADJUSTMENT
DEFLECTION
YOKE
Adjust tabs angle to superimpose
red/blue and green vertical line
-Jr
Figure- 3 BLUE/RED AND GREEN LINE MOVEMENT
–11–
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