Purity And Convergence Adjustment - Sanyo CP29EF1 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:
Signals: Use a pattern generator which can output red,
green, blue and white raster and crosshatch
pattern signals.
Procedure: Carry out purity adjustment first, and then carry
out convergence adjustment.
Preparation: The deflection yoke may have several
correction magnets attached to its outer
edge. If replacing the picture tube, the
positions of the magnets can be changed and
they can be re-used, so remove these
magnets and keep them safely so that they
do not get lost.
PURITY ADJUSTMENTS
1. Place the picture so that its front faces west.
2. Insert the power plug into a wall outlet, and then turn on
the power for the TV and de-magnetize the TV using its
own degaussing circuit.
3. Loosen the screw which is holding the deflection yoke
(with integrated purity magnets), and then move the
deflection yoke forward as far as it will go. Remove the
rubber wedge at this time.
4. Turn off the red and blue raster so that only the green
raster is on.
5. Adjust the angle between the tabs (wings) on purity
magnets to center the vertical green belt in the picture
tube screen. (See Figures 2 and 3.)
NOTE: This adjustment can only be carried out by
changing the angle, not by rotating the tabs up and
down.
6. Gently move the deflection yoke back to the position
where the green band fills the whole of the picture tube
screen, and then tighten the screw to secure the
deflection yoke in place.
7. If there is any color distortion around the edges, correct
it by attaching magnets to the outer edge of the
deflection yoke. The magnets should be attached so
that the line running from the position of the distortion to
the center of the picture tube intersects the deflection
yoke. The colors on the magnets indicate the north and
south poles of the magnets. Attach the magnets in
whichever direction causes the distortion to
disappear.(See Figures 1 and 4. The south and north
pole positions are shown as a guide.)
8. Switch the screen to red and blue rasters and check that
there is no color distortion. If there is any distortion,
adjust the angles of purity magnets tabs or the forward-
back position of the deflection yoke, or change the
attachment positions of the
correction magnets.
Figure 1
Correction
magnet
Figure 2
Change the angle to adjust the green band so that it is
centered in the screen.
Figure 3
Figure 4
N
Magnet attachment position
S
-17-
Move the deflection
yoke back and forth to
adjust the purity
FOUR-POLE
MAGNET TABS
3
ANGLE
OF TABS
PURITY
MAGNET
TABS
Color Distortion
Deflection Yoke
outer edge
Rubber wedge
Deflection yoke
mounting scrrew
SIX-POLE
MAGNET TABS
GREEN band