Purity Adjustment - JVC AV-21W83 Service Manual

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PURITY ADJUSTMENT

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Note: The final adjustment of CONVERGENCE must be done after the
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FOCUS adjustment. (CONVERGENCE is changed by FOCUS
adjustment.)
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When makes difference by FOCUS adjustment, should be
reconfirming PURITY adjustment.
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1. Demagnetize CRT with the demagnetizer.
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2. Loosen the retainer screw of the deflection yoke.
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3. Remove the wedges.
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4. Input a green raster signal from the signal generator, and turn the
screen to green raster.
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5. Move the deflection yoke backward.
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6. Bring the long lug of the purity magnets on the short lug and position
them horizontally. (Fig. 2)
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7. Adjust the gap between two lugs so that the GREEN RASTER will
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come into the centre of the screen. (Fig. 3)
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8. Move the deflection yoke forward, and fix the position of the deflec-
tion yoke so that the whole screen will become green.
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9. Insert the wedge to the top side of the deflection yoke so that it will
not move.
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10. Input a crosshatch signal.
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11. Verify that the screen is horizontal.
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12. Input red and blue raster signals, and make sure that purity is prop-
erly adjusted.
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CRT
• P/C MAGNETS
P : PURITY MAGNET
4 : 4 POLES (convergence magnets)
6 : 6 POLES (convergence magnets)
Long lug
Short lug
(FRONT VIEW)
No. 52016
AV-21W83
AV-21W93
AV-21W93B
WEDGE
DEFLECTION
YOKE
P
4 6
P / C
MAGNETS
Fig. 1
PURITY MAGNETS
Bring the long lug over the short lug
and position them horizontally.
Fig. 2
GREEN RASTER
CENTRE
Fig. 3
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