SERVICING
3828VD0171G
3-4
DIGITAL FCS - SERVICING
HORIZONTAL-TILT WEDGE ADJUST-
MENT
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, which-
ever 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 the 3 and 9 o’clock should
be maintained during this operation.
When the 3 wedges are firmly installed
and positioned for acceptable conver-
gence, lock the wedges in place by ap-
plying a 2.5 inches long strip of tape
across the tabs of each wedge firmly
against the CRTM 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 ver-
tical tilt in the opposite (up) direc-
tion 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
4 Pole Magnets
Clamp and Screw
6 Pole Magnets
2 Pole Magnets
2" To 3"
MAGNET
positions and secure each wedge with a
piece of tape, as described above.
IMPROVING CRT CORNER PURITY
CRTs that display corner purity prob-
lems even after following the service
procedures can be modified with a pic-
ture correction kit (P/N 949-00050).
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 prop-
erly. Fully degauss the CRT before in-
stalling correction magnets.
MODIFICATION 1. Place the magnet on
the CRT funnel as shown in the figure
displayed below, in the quadrant ex-
hibiting 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.
