Adjustments - Zenith Presentation Series Service Manual

ADJUSTMENTS

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 converged
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. Convergence at 3
and 9 o'clock should be maintained during 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)
position. Follow through on the horizontal tilt
adjustment by using the 2 and 10 o'clock positions
and secure each wedge with a piece of tape, as described
above.
6 Pole Magnets
2 Pole Magnets
4 Pole Magnets
SR23 - 923-03509
ADJUSTMENTS
X
Clamp and Screw
IMPROVING CRT CORNER PURITY
CRTs that display corner purity problems even after
following the service procedures can be modified with
a picture correction kit (P/N 949-50). The purity can
be improved by placing a picture-correction magnet
(included in the kit) on the CRT funnel. Refer to the
following modification steps and illustration to place
the magnet properly. 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 exhib-
iting impurity.
2. Rotate the magnet in place to the position shown
for best purity.
3. Place 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
magnet shield, any apparent purity correction
will disappear after degaussing. Reposition
the correction magnet off the internal shield
and degauss again.
3-13
2" To 3"
MAGNET
CS - SERVICING