Sharp 14VT10X1, Service Manual

Page: 44 / 138

PURITY ADJUSTMENT
Note:
l During the adjustment, keep the unit facing the
east.
Purity
adjustment
Prior to the purity adjustment, warm
up
the unit
with beam current of more than for
more than 30 minutes.
2. Receive the green signal alone and adjust the
beam current to about
3. Fully degauss the CRT with the degaussing coil.
4. Before the purity adjustment,
is needed to
roughly adjust the static convergence.
5. Set the purity magnet
at
the position which gives
zero (0) magnetic field.
Adjustment:
6. Observe the green spots
(“a”
and “b”) with a
microscope as shown Fig. and adjust the
purity magnet so that they are at the specified
landing position.
Figure 3-3.
7. If the right and left green spots are both
deviated outwards from their landing positions
as shown in Fig. 3-4 push the deflection yoke
forwards until their positions are corrected.
,
,
,
The landing is shifted
outwards.
Figure 3-4.
T h e b e a m
to right.
Figure 3-5.
The beam landing shifted
to
F i g u r e 3 - 6 .
9. Adjust the purity magnet so that the beam
landing is correct at either of the part,
right and left parts of screen, then check that
the green beams at four corners of screen are
all correctly positioned.
Finally, check that the beam landing at any pat
of screen is satisfactory with the Rank “B”
specifications.
If the green beam is positioned to mix with the
o t h e r p u l l t h e d e f l e c t i o n y o k e
backward.
l Outside of the specified landing: To front of the
deflection yoke
l Inside of the specified -landing: To back of the
deflection yoke
Receive “MONOSCOPE PATTERN” signal or
“CROSSHATCH PATTERN” signal.
12. Set the raster rotation at position (with the
unit fasing the east.)
13. Tighten the screws of the deflection coil.
Tightening torque: 11 kg 2kg
8. If the beam landing is shifted to right or to left as
shown in Figs. 3-5. and adjust the opening
degree of the purity magnet so that the beam
landing is correctly positioned.
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