Sharp VT-3448X, Service Manual

Page: 14 / 144

PURITY ADJUSTMENT
PURITY ADJUSTMENT
First of all, let a beam current of over flow
in the set to warm it up for minutes or longer.
(over for
Keep the purity magnet in the zero magnetic field
in advance. Roughly adjust the static conver-
gence.
Receive the green-only signal. Adjust the
beam current to about (about for
the cathode ray tube enough with the
coil.
ADJUSTMENT
Eastward magnetic field specified
Observe the beam landings “a” and as
shown in Fig. A, through a microscope. Ad-
just the landings as specified.
If the right and left landings are equally out-
ward as shown in Fig. move the deflection
yoke forward.
If the right or left landing is shifted to the right
or to the left, as shown in Fig. C and Fig.
adjust the opening angle of the purity magnet.
Make sure the right and left beam landings are
just as specified about the screen center. Now
check the cathode ray tube corners.
Be sure that all the landings are at rank
If any other appears on the screen,
move the deflection yoke back and forth.
LANDING ERROR
l
Outward: Move the deflection yoke forward.
l
Inward: Move the deflection yoke backward.
Receive the monoscope pattern signal.
RASTER ROTATION
Adjust the raster rotation to eastward.
l
Adjustment error : 0 mm
Tighten up the deflection coil screws.
l
Tightening torque : kg
Note : Each time the key is pressed,
the screen changes as follows.
a b
- - - - - -
I
Left
,
Left
Fig. A
Right
Beam landing equally outwards
Fig. B
.
:I’
m
Left
landing shifted to right.
Fig. C
Right
Right
Beam landing shifted to the left.
Fig. D