Purity And Convergence; Purity Adjustment - Sanyo C21ZM40 Service Manual

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 usingan external
degaussing coil. When replacing picture tube or deflection
yoke, mount deflectionyoke and purity - convergence
magnets assembly properly, s ee figures 1 and 4.
2.Turn Red and Blue guns offand provideonly Green raster.
Rotate Screen control to fully counterclockwise. Rotate Red
and Blue Bias controls fully counterclockwise. Slowly rotate
Green Biascontrol clockwke to produce Green raster.
3. Loosen the screw holdingthe Deflection Y oke and remove
the 3 Rubber Wedges, and slidethe Deflection Yoke fully
frontward.
4. Rotate and spread the Tabs of the two PurityMagnets to
centerthevertical green belt inthe picture screen. The Purity
Magnets are also adjustedto obtainvertical centering of the
raster.
5. Slowly slidethe Deflection Yoke backward until a uniform
green screen isobtained.
6. Check the purity of the red and blue screens foruniformity,
turn off other Colours to check this (use bias controls).
Readjustthe yoke position ifnecessary until all screens are
pure.
7. Adiusteach Bias control and screen control to
obtain white
.
raster, R efer to Gray Scale Adjustment.Ifpartof the picture
screen
is coloured, adjust the Deflection Yoke position
forward or backward slightly.
FOUR-POLE
MAGNET TABS
Px
SIX- POLE
~AGNET TABS
P~
A
ANGLE 9
OF TABS
1!
(
PURITY
MAGNET
TABS
'~
Figure- 1. PURITY AND CONVERGENCE MAGNETS
Adjusttabs angleto superimpose
blueand red vertical line
J
Adjusttabstogether to
RED
+
I_
superimpose red and
1--- : L/
bluehorizontal line
+---
BLUE
Figure-2 BLUE AND RED LINE MOVEMENT
8.Tightenthe mounting screw of the Deflection Y oke. Adjust
Convergence next.
CENTER CONVERGENCE ADJUSTMENT
1.
Use a dotcrosshatch pattern signal.
2.Turn Red and Blue guns on and turnoffGreen gun. Adjust
the angle between the Tabs of the Four Pole Magnet 1and
2,and superimpose the Red and Blue vertical l inesin the
centerarea ofthe picture screen.Refertofigure 2.
3. Keeping the mutual angle of the Tabs of the Four Pole
Magnet turnthem together to superimpose the Blue and Red
horizontal lines inthe centerarea ofthe picture screen.Refer
tofigure 2.
4.Turn Green gun on and adjust Six Pole Magnet 3 and 4 s that
the Green line superimposed on the Red/Blue lines.
Thisisthe same procedureused insteps2 and 3.
Refertofigure 3.
OUTER AREA CONVERGENCE ADJUSTMENT
Slightly l oosen the screw holdingthe Deflection Y oke. Adjust
the Deflection Y oke to converge the detail i nthe outerarea (left
sideand right side) ofthe picture screen by orbital movement of
the frontof the Yoke, then secure the Deflection Yoke in
appropriatepositionby puttingthe wedges as illustrated.
Tightenscrew holding the Deflection Yoke.
DEFLECTION YOKE
Figure- 4. ADJUSTMENT DEFLECTION YOKE
Adjusttabsangletosuperimpose
red/blue and green vertical line
J
Adjusttabstogether to
+
GREEN
I_
/
superimpose red/blue
\--- [--_l_
and green horizontal line
BLUE/RED
Figure- 3 BLUE/RED AND GREEN LINE MOVEMENT
–lo-