Sony KV-20S90 Service Manual ▷ View online
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KV-20S90 / 21SE43C
1-1. REAR COVER REMOVAL
1-2. CHASSIS ASSEMBLY REMOVAL
1-3. SERVICE POSITION
SECTION 1: DISASSEMBLY
Screw +BVTP 4x16
Chassis Assembly
C Board
A Board
Screw +BVTP 4x16
2 Screws +BVTP 4x16
Claw
Rear Cover
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KV-20S90 / 21SE43C
1. Discharge the anode of the CRT and remove the anode cap.
2. Unplug all interconnecting leads from the defl ection yoke, neck
assembly, degaussing coils and CRT grounding strap.
3. Remove the C Board from the CRT.
4. Remove the chassis assembly.
5. Loosen the neck assembly fi xing screw and remove.
6. Loosen the defl ection yoke fi xing screw and remove.
7. Place the set with the CRT face down on a cushion and remove
the degaussing coil holders.
8. Remove the degaussing coils.
9. Remove the CRT grounding strap and spring tension devices.
10. Unscrew the four CRT fi xing screws [located on each CRT
corner] and remove the CRT [Take care not to handle the CRT
by the neck].
by the neck].
1-4. PICTURE TUBE REMOVAL
WARNING: BEFORE REMOVING THE ANODE CAP
High voltage remains in the CRT even after the power is disconnected. To avoid electric shock,
discharge CRT before attempting to remove the anode cap. Short between anode and CRT
coated earth ground strap.
High voltage remains in the CRT even after the power is disconnected. To avoid electric shock,
discharge CRT before attempting to remove the anode cap. Short between anode and CRT
coated earth ground strap.
Coated
Earth
Ground
Strap
Earth
Ground
Strap
ANODE CAP REMOVAL PROCEDURE
WARNING: High voltage remains in the CRT even after the power is disconnected. To avoid electric shock, discharge CRT before attempting to
remove the anode cap. Short between anode and coated earth ground strap of CRT.
NOTE: After removing the anode cap, short circuit the anode of the picture tube and the anode cap to either the metal chassis, CRT shield, or
carbon painted on the CRT.
remove the anode cap. Short between anode and coated earth ground strap of CRT.
NOTE: After removing the anode cap, short circuit the anode of the picture tube and the anode cap to either the metal chassis, CRT shield, or
carbon painted on the CRT.
HOW TO HANDLE AN ANODE CAP
1. Do not use sharp objects which may cause damage to the surface of the anode
cap.
2. To avoid damaging the anode cap, do not squeeze the rubber covering too hard.
A material fi tting called a shatter-hook terminal is built into the rubber.
3. Do not force turn the foot of the rubber cover. This may cause the shatter-hook
terminal to protrude and damage the rubber.
10
1
9
8
7
6
5
4
3
2
a
b
Anode Button
c
Turn up one side of the rubber cap in
the direction indicated by arrow a .
the direction indicated by arrow a .
1
Use your thumb to pull the rubber
cap fi rmly in the direction indicated
by arrow b .
cap fi rmly in the direction indicated
by arrow b .
2
When one side of the rubber cap separates from
the anode button, the anode cap can be removed
by turning the rubber cap and pulling it in the
direction of arrow c .
the anode button, the anode cap can be removed
by turning the rubber cap and pulling it in the
direction of arrow c .
3
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KV-20S90 / 21SE43C
The following adjustments should be made when a complete
realignment is required or a new picture tube is installed.
realignment is required or a new picture tube is installed.
These adjustments should be performed with rated power supply
voltage unless otherwise noted.
voltage unless otherwise noted.
Set the controls as follows unless otherwise noted:
VIDEO MODE: Standard
PICTURE CONTROL: Normal
BRIGHTNESS CONTROL: Normal
VIDEO MODE: Standard
PICTURE CONTROL: Normal
BRIGHTNESS CONTROL: Normal
SECTION 2: SET-UP ADJUSTMENTS
Perform the adjustments in order as follows:
1.
Beam Landing
2.
Convergence
3.
Focus
4.
Screen (G2)
5.
White Balance
Note Test Equipment Required:
1.
Color Bar Pattern Generator
2.
Degausser
3.
DC Power Supply
4.
Digital Multimeter
2-1. BEAM LANDING
Before beginning adjustment procedure:
1. Degauss the entire screen.
2. Feed in the white pattern signal.
ADJUSTMENT PROCEDURE
1. Input a raster signal with the pattern generator.
2. Loosen the defl ection yoke mounting screw, and set the purity control
to the center as shown below:
Purity Control
3. Turn the raster signal of the pattern generator to green.
4. Move the defl ection yoke backward, and adjust with the purity control
so that green is in the center and red and blue are even on both
sides.
sides.
Blue
Red
Green
5. Move the defl ection yoke forward, and adjust so that the entire screen
becomes green.
6. Switch over the raster signal to red and blue and confi rm the
condition.
7. When the position of the defl ection yoke is determined, tighten it with
the defl ection yoke mounting screw.
8. If landing at the corner is not right, adjust by using the disk magnets.
a
c
b
d
b
a
c
d
Purity control
corrects this area
Disk magnets
or rotatable disk
magnets correct
these areas (a-d)
Deflection yoke positioning
corrects these areas
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KV-20S90 / 21SE43C
2-2. CONVERGENGE
Before starting convergence adjustments:
1 Perform FOCUS, VLIN and VSIZE adjustments.
2. Set BRIGHTNESS control to minimum.
3. Feed in dot pattern.
VERTICAL STATIC CONVERGENCE
1. Adjust V. STAT magnet to converge red, green and blue dots in the
center of the screen (Vertical movement adjust V.STAT RV701 to
converge).
converge).
B
G
R
Center dot
R G B
V.STAT magnet
2. Tilt the V. STAT magnet and adjust static convergence to open or close
the V. STAT magnet.
When the V. STAT magnet is moved in the direction of arrow a and b,
red, green, and blue dots move as shown below:
B
R
G
B
R
G
R
G B
B
G R
1
2
b
b
b
b
b
b
b
a
a
b
a
a
a
a
3
R
G
B
B
G
R
If the blue dot does not converge with the red and green dots, peform
the following:
1. Move BMC magnet (a) to correct insuffi cient H.Static convergence.
the following:
1. Move BMC magnet (a) to correct insuffi cient H.Static convergence.
2. Rotate BMC magnet (b) to correct insuffi cient V.Static convergence.
3. In either case, repeat Beam Landing Adjustment.
BMC MA
GNET
PURITY
V.STAT
b
BMC magnet
a
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