Sony KV-21FT1B, Service Manual

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14
Purity control corrects
this area
Disk magnets or
rotatable disk
magnets correct
these areas (a-d)
Deflection yoke positioning
corrects these areas
a
c d
b
Disk Magnets
GREEN
BLUE
RED
Preparation:
1. In order to reduce the influence of geomagnetism on the
set’s picture tube, face it in an easterly or westerly direction.
2. Switch on the set’s power and degauss with the degausser.
1. Input an all white signal from the pattern generator. Set the
Contrast and Brightness to normal.
2. Set the pattern generator raster signal to Red.
3. Move the deflection yoke forward and adjust with the
purity control so that the Red is at the centre and the Blue
and Green take up equally sized areas on each side of the
screen. [See Fig.3-1 - 3-3].
4. Move the deflection yoke backwards and adjust so that the
entire screen becomes Red. [See Fig.3-1]
5. Switch the raster signal to Blue, then to Green and verify
the condition.
6. When the position of the deflection yoke has been
determined, fasten the deflection yoke with the screws.
7. If the beam does not land correctly in all the corners, use a
magnet to correct it. [See Fig.3-4]
•
When complete readjustment is necessary or a new picture
tube is installed, carry out the following adjustments.
•
Unless there are specific instructions to the contrary, carry
out these adjustments with the rated power supply.
•
Unless there are specific instructions to the contrary, set the
controls and switches to the following settings :
Contrast .................... 80% [or remote control normal]
Brightness ................... 50%
Carry out the adjustments in the following order :
3-1.
Beam Landing.
3-2. Convergence.
3-3. Focus.
3-4. White Balance.
Note : Test equipment required.
1.
Color bar/pattern generator.
2. Degausser.
3. Oscilloscope.
4. Digital multimeter.
SECTION 3
SET-UP ADJUSTMENTS
3-1. Beam Landing
Caution :
High voltages are present on the Deflection yoke terminals
- take care when handling the Deflection yoke whilst carrying
out adjustments.
Fig.3-4
Fig. 3-1.
Fig. 3-3.
Fig. 3-2.
Purity