LG RE-21FB50RX Service Manual page 15

1.ADJUST YOKE Z-AXIS FIRST
TO GET EQUAL BLUE
COLOR CIRCLES
MAGNETS
8. Referring to above, perform the following two steps:
a. Adjust the yoke Z-axis to obtain equal blue circles.
b. Adjust the appropriate beam bender tabs to obtain correct
purity (four equal circles).
9. After correct purity is set, tighten the yoke clamp screw and
remove the two screen magnets.
10. Remove the AC power and rotate the receiver 180 degrees
(facing "magnetic south").
11. Reconnect the internal degaussing coil.
12. Turn the receiver on for 10 seconds (make sure the receiver
came on) to perform internal degaussing, and then turn the
receiver off.
13. Unplug the internal degaussing coil.
14. Turn on the receiver and check the purity by holding one (1)
round magnet at the 3 o'clock and a second round magnet at
9 o'clock position. If purity is not satisfactory, repeat steps 8
through 14.
15. Turn off the receiver and reconnect the internal degaussing
coil.
¡ Convergence Adjustment
Caution: This procedure DOES NOT apply to bonded yoke and
picture tube assemblies.
Do not use screen magnets during this adjustment
procedure. Use of screen magnets will cause an
incorrect display.
1. Remove AC power and disconnect the internal degaussing
coil.
2. Apply AC Power and set the brightness to the Picture Reset
condition. Set the Color control to minimum.
3. Make a horizontal line.
4. Adjust the Red, Green and Blue Bias controls to get a dim
white line.
5. Restore the screen by removing the horizontal line.
RED
2 .ADJUST BEAM BENDER 2 POLE
MAGNET TO GET FOUR EQUAL
COLOR CIRCLES
6. Reconnect the internal degaussing coil and apply AC power.
7. Turn the receiver on for 10 seconds to perform internal
degaussing and then turn the receiver off again.
8. Unplug the internal degaussing-coil.
9. Turn on the receiver, connect a signal generator to the VHF
antenna terminal and apply a crosshatch signal.
Caution: During the convergence adjustment procedure, be
very careful not to disturb the purity adjustment tabs
are accidentally move, purity should be confirmed
before proceeding with the convergence adjustments.
Note: Make sure the focus is set correctly on this instrument
before proceeding with the following adjustment.
10. Converge the red and blue vertical lines to the green vertical
line at the center of the screen by performing the following
steps (below TABLE).
a. Carefully rotate both tabs of the 4-pole ring magnet
simultaneously in opposite directions from the 12 o'clock
position to converge the red and blue vertical lines.
b. Carefully rotate both tabs of the 6-pole ring magnet
simultaneously in opposite directions form the 12 o'clock
position to converge the red and blue (now purple)
vertical lines with the green vertical line.
11. Converge the red and blue horizontal with the green line at
the center of the screen by performing the following steps.
(below TABLE)
a. Carefully rotate both tabs of the 4-pole ring magnet
simultaneously in the same direction (keep the spacing
between the two tabs the same) to converge the red and
blue horizontal lines.
b. Carefully rotate both tabs of the 6-pole ring magnet
simultaneously in same direction (keep the spacing
between the two tabs the same) to converge the red and
blue (now purple) horizontal lines with the green
horizontal line.
c. Secure the tabs previsouly adjusted by locking them in
place with the locking tabs on the beam bender.
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RED