-16-
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-con-
vergence 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 counterclock-
wise. Slowly rotate Green Bias control clockwise to pro-
duce Green raster.
3. Loosen the screw holding the Deflection Yoke and
remove the 3 Rubber Wedges, and slide the Deflection
Yoke fully forward.
4. Rotate and spread the Tabs of the two Purity Magnets
to centre the vertical green belt in the picture screen.
The Purity Magnets are also adjusted to obtain vertical
centring of the raster.
5. Slowly slide the Deflection Yoke backward until a uni-
form green screen is obtained.
6. Check the purity of the red and blue screens for unifor-
mity, turn off other colours to check this (use bias con-
trols). 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 part of
the picture screen is coloured, adjust the Deflection
Yoke position forward or backward slightly.
8. Tighten the mounting screw of the Deflection Yoke.
Adjust Convergence next.
CENTRE 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 1 and 2, and superimpose the Red and Blue
vertical lines in the centre 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 centre area of the picture
screen. Refer to figure 2.
4. Turn Green gun on and adjust Six Pole Magnet 3 and 4
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.
RED
BLUE
Adjust tabs together to
superimpose red and
blue horizontal line.
Figure- 2 BLUE AND RED LINE MOVEMENT
Figure- 3 BLUE/RED AND GREEN MOVEMENT
Adjust tabs together to
superimpose red/blue
and green horizontal
line.
Adjust tabs angle to superimpose
blue and red vertical line.
Adjust tabs angle to superimpose
red/blue and green vertical line.
GREEN
BLUE / RED
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