Purity Adjustment - JVC AV-20N3 Service Manual

PURITY / CONVERGENCE ADJUSTMENT

PURITY ADJUSTMENT

1. Demagnetize CRT with the demagnetizer.
2. Loosen the retainer screw of the deflec tion yoke.
3. Remove the wedges.
4. Input a green raster signal from the signal generator, and turn
the screen to green raster.
5. Move the deflection yoke backward.
6. Bring the long lug of the purity magnets on the short lug and
position them horizontally. (Fig.2)
7. Adjust the gap between two lugs so that the GREEN RASTER
will come into the c enter of the screen. (Fig.3)
8. Move the deflection yoke forward, and fix the pos ition of the
deflection yoke so that the whole screen will bec ome green.
9. Ins ert the wedge to the top side of the deflection yoke so that it
will not move.
10. Input a cross hatch signal.
11. Verify that the screen is horizontal.
12. Input red and blue raster signals, and make sure that purity is
properly adjusted.
CR T
Long lug
Short lug
Bring the long lug over the short lug
and position them horizontally.
(F RONT VIEW )
No. 52025
W EDGE
DEF LECT ION
YOKE
P
4 6
P / C
MAGNET S
# P/C MAGNETS
P : PURITY MAGNET
4 : 4 POLES (convergence magnets)
6 : 6 POLES (convergence magnets)
Fig.1
PURIT Y MAGNET S
Fig.2
GREEN RASTER
CEN TER
Fig.3
AV-20N3
AV-20NMG3
AV-20NMG3B
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