11
9. SUB-BRIGHTNESS ADJUSTMENT
1) Tune in a color program.
2) Set the CONTRAST control to maximum and the BRI-
GHTNESS control to maximum and the SHARPNESS
control to the center position.
3) Set the COLOR and TINT controls to center.
4) Set the SUB-BRIGHT control R554 to center and leave
the receiver on five minutes in this state.
5) Watching the picture carefully, adjust the SUB-BRIGHT
control in the position where the picture does not show
evidence of blooming in high brightness area and not
appear too dark in low bright area.
6) Check for BRIGHTNESS controls at both extremes.
7) If the picture does not appear dark with the
CONTRAST and BRIGHTNESS control turned to
minimum, or not appear bright with the controls turned
to maximum, adjust the SUB-BRIGHT control again for
an acceptable picture.
10. CONVERGENCE MAGNET ASSEMBLY
POSITIONING
If Convergence magnet assembly and rubber wedges
need mechanical positioning follow figure 2.
10-1. COLOR PURITY ADJUSTMENT
NOTE
: Before attempting any purity adjustments, the
receiver should be operated for at least 15
minutes.
1) Demagnetize the picture tube with a degaussing coil.
2) Adjust the CONTRAST and BRIGHTNESS controls to
maximum
3) Adjust RED and BLUE Bias controls (R971 and R973)
to provide only a green raster. Adjust the GREEN BIAS
control (R972) if necessary.
4) Loosen the clamp screw holding the yoke, and slide
the yoke backward th provide vertical green
belt(zone)in the picture screen.
5) Remove the Rubber Wedges.
6) Rotate and spread the tabs of the purity magnet (See
figure 2) around the neck of the picture tube until the
green belt is in the center of the screen. At the same
time, center the raster vertically.
7) Move the yoke slowly forward until a uniform green
screen is obtained. Tighten the clamp screw of the
yoke temporarily.
8) Check the purity of the red and blue raster by adjusting
the BIAS controls.
9) Obtain a white raster, referring to CRT GRAY SCALE
ADJUSTMENT
10) Proceed with covergence adjustment.
DEFLECTION
YOKE
CONVERGENCE
MAGNET ASS'Y
TEMPORARY
MOUNTING
RUBBER
WEDGES
DEF.
YOKE
ADHESIVE
GLASS CLOTH
TAPE
Fig. 2 Rubber Wedges Location
PICTURE TUBE
RUBBER
WEDGES
30
30
30
