LG RU-27FB30C Series Service Manual page 38

VERTICAL-TILT WEDGE ADJUSTMENT
The vertical lines at 6 and 12 o'clock are converged by
vertically tilting the yoke and inserting a wedge at the
top of the yoke until it is firmly seated between the CRT
glass and the horizontal coils.
HORIZONTAL-TILT WEDGE ADJUSTMENT
The vertical lines at 3 o'clock and 9 o'clock are con-
verged by horizontally tilting the yoke and inserting a
wedge. Adjust first at 4 or 8 o'clock, whichever has the
larger space, until the wedge is firmly seated between
the CRT glass and yoke coils. Then, insert the 3rd wedge
in the remaining horizontal tilt position until it is firmly
seated between the CRT glass and yoke coils. Conver-
gence at the 3 and 9 o'clock should be maintained dur-
ing this operation.
When the 3 wedges are firmly installed and positioned
for acceptable convergence, lock the wedges in place
by applying a 2.5 inches long strip of tape across the
tabs of each wedge firmly against the CRT glass. The
CRT glass surface should be clean and free of dust and
other foreign material.
UNUSUAL TILT CASE
There may be some instances where the picture tube
and yoke will require vertical tilt in the opposite (up)
direction to obtain convergence. In such cases, insert
the vertical tilt wedge at the bottom (6 o'clock) posi-
tion. Follow through on the horizontal tilt adjustment
by using the 2 and 10 o'clock positions and secure wedge
with a piece of tape, as described above.
2 Pole Magnets
4 Pole Magnets
3828VD0210A
SERVICING
Clamp and Screw
6 Pole Magnets
IMPROVING CRT CORNER PURITY
CRTs that display corner purity problems even after fol-
lowing the service procedures can be modified with a
picture correction kit. The purity can be improved by
placing a picture-correction magnet (included in the
kit) on the CRT funnel. Refer to the following modifica-
tion steps and illustration to place the magnet prop-
erly. Fully degauss the CRT before installing correction
magnets.
MODIFICATION
1. Place the magnet on the CRT funnel as shown in the
figure displayed below, in the quadrant exhibiting
impurity.
2. Rotate the magnet in place to the position shown
for best purity.
3. Piece a piece of 1/2" by 2" long Fiberglass tape over
the magnet to hold it in place.
4. Degauss the CRT once magnet is in place to insure
that the magnet is not over the internal magnet
shield.
Note: If the magnet is placed over the internal mag
net shield, any apparent purity correction will
disappear after degaussing. Reposition the cor
rection magnet off the internal shield and de
auss again.
3-6
2" To 3"
MAGNET
FCN - SERVICING