Adjustment - Sanyo C20VTI I-M Service Manual

8. Purity and Convergence Adjustment
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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 part of the picture
screen is coloured, adjust the Deflection Yoke position
forward or backward slightly.
FOUR- POLE
MAGNET TABS
SIX- POLE
MAGNET TABS
A
PURITY V .
MAGNET
TABS
Figure- 1. PURITY AND CONVERGENCE MAGNETS
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 YOKP
Figure- 4. ADJUSTMENT DEFLECTION YOKE
Adjust tabs angle to superimpose
Adjust tabs angle to superimpose
blue and red vertical line red/blue and green vertical line
J Adjust tabs together to
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Adjust tabs together to
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+
GREEN
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superimpose red/blue
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and green horizontal line
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BLUE
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BLUE/RED
Figure-2 BLUE AND RED LINE MOVEMENT Figure-3 BLUE/RED AND GREEN LINE MOVEMENT
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