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ADJUSTMENT
COLOUR PURITY ADJUSTMENT
For best results, it is recommended that the purity adjust-
ment be made in final receiver location. If the receiver will
be moved, perform this adjustment with it facing east. The
receiver must have been operating 15 minutes prior to this
procedure and the faceplate of the CRT must be at room
temperature. The receiver is equipped with an automatic
degaussing circuit. However, if the CRT shadow mask has
become
excessively
magnetized,
it may be necessary
to
degauss it with manual coil. Do not switch the coil OFF
while the raster shows any effect from the coil.
The following procedure is recommended while using a Dot
Generator.
1. Check for correct location of all neck components.
(See Figure 6.)
2. Rough-in the static convergence
at the center of the
CRT, as explained in the static convergence procedure.
3. Rotate the picture control to centre of its rotation range
and rotate Brightness control to maximum CW position.
4. To obtain a blank raster, connect a short clip lead be-
tween pin 2
of IC801 and earth. Then, rotate screen
control CW until normal raster is obtained.
5. Rotate the Red Bias and Blue Bias controls to maximum
CCW position Rotate the Green bias control sufficiently
in a CW direction to produce a green raster.
6. Loosen
the deflection
yoke
tilt adjustment
wedges
(three), loosen
the deflection yoke clamp screw and
push the deflection yoke as close as possible to the CRT
screen.
7, Begin the following adjustment with the tabs on the
round purity magnet rings set together, initially move
the tabs on the round purity magnet rings to the side of
the CRT neck. Then, slowly separate the two tabs while
_ at the same time rotating them to adjust for a uniform
green vertical band at the centre of the CRT screen.
8. Carefully slide the deflection yoke backward to achieve
green purity (uniform green screen).
NOTE:
Center
purity
was obtained by adjusting the
tabs on the round purity magnet rings, outer edge
purity was obtained by sliding the deflection yoke
forward. Tighten the deflection yoke clamp screw.
9, Check for red and blue field purity by reducing the
output
of the Green
Bias control and alternately in-
creasing output of Red and Blue Bias controls and touch
up adjustments, if required.
10. Disconnect between pin @2 of IC801 and earth, if
connect in connect in step 4.
11. Perform BLACK
AND WHITE
TRACKING procedure.
STATIC (CENTER) CONVERGENCE ADJUSTMENT
1. Switch the Receiver ON and allow it to warm up for 15
minutes.
2. Connect
the output of a Crosshatch Generator to the
Receiver and, concentrating on the centre of the CRT
screen, proceed as follows:
a. Locate the pair of 4 pole magnet rings. Rotate indi-
vidual rings (change spacing between
tabs) to con-
verge the vertical red and blue lines. Rotate
the
pair of rings (maintaining spacing between tabs) to
converge the horizontal red and blue lines.
b. After completing red and blue centre convergence,
locate the pair of 6 pole magnet rings. Rotate indi-
vidual rings (change spacing between
tabs) to con-
verge the vertical red and blue (magenta) and green
lines. Rotate the pair of rings (maintaining spacing
between
tabs) to converge
the horizontal
red and
blue (magenta) and green lines.
DEFLECTION
YOKE
PURITY
MAGNETS
CLAMP
SCREW
6 POLE
CONV.
MAGNETS
L, POLE CONV,
MAGNETS
L DEFLECTION
YOKE
TILT ADJUSTMENT
WEDGE
|
DEFLECTION
YOKE
TAPE
Figure 6. Picture Tube Neck Components Location
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