Sony KV-28FS20U Service Manual ▷ View online
17
5 Neck assy
Cushion
8 Degaussing coils
9 Spring Extension
2 Chassis assy
10 Four PT screws
11 Picture tube
2-7. PICTURE TUBE REMOVAL
Anode button
a
* REMOVING PROCEDURES.
Turn up one side of the rubber cap in
the direction indicated by the arrow a
the direction indicated by the arrow a
1
2 Using a thumb pull up the rubber cap
firmly in the direction indicated by the
arrow b
firmly in the direction indicated by the
arrow b
3 When one side of the rubber cap is
separated from the anode button, the
anode-cap can be removed by turning
up the rubber cap and pulling it up in
the direction of the arrow c
separated from the anode button, the
anode-cap can be removed by turning
up the rubber cap and pulling it up in
the direction of the arrow c
b
b
c
Note : Short circuit the anode of the picture tube and the anode cap to the metal chassis, CRT
shield or carbon paint on the CRT, after removing the anode.
shield or carbon paint on the CRT, after removing the anode.
• REMOVAL OF ANODE-CAP
•
HOW TO HANDLE THE ANODE-CAP
1
To prevent damaging the surface of the anode-cap do not use sharp materials.
2
Do not apply too great a pressure on the rubber, as this may cause damage to the
anode connector.
anode connector.
3
A metal fitting called a shatter hook terminal is fitted inside the rubber cap.
Do not turn the rubber foot over excessively this may cause damage if the shatter
hook sticks out.
Do not turn the rubber foot over excessively this may cause damage if the shatter
hook sticks out.
3 C board
Anode cap
1
1
7 DGC holders
6 Deflection yoke
4 VM Board
18
Fig 2
NUMERICAL MARKINGS
ATTENTIONATTENTION
THIS PLA
TE MUST BE REMO
VED
(TURN 180' NO
T FLIP O
VER)
AFTER CUTTING A
W
A
Y
FOR SAFETY REASONS
THIS PLA
TE MUST BE REMO
VED
AFTER CUTTING A
W
A
Y FOR
THE SAFETY REASON.
2
2
2
2
1
1
4
4
3
4
4
REFITTING
REFITTING
ATTENTIONATTENTION
THIS PLA
TE MUST BE REMO
VED
(TURN 180' NO
T FLIP O
VER)
AFTER CUTTING A
W
A
Y
FOR SAFETY REASONS
2
2
2
2
1
1
Cut points
Fig 1
MAIN BRACKET
INSERT FROM
THE BOTTOM
SIDE
THE BOTTOM
SIDE
FIG 3
Fig 4
REMOVAL AND REPLACEMENT OF THE MAIN-BRACKET
BOTTOM PLATES.
BOTTOM PLATES.
(1)
REMOVING THE PLATES
In the event of servicing being required to the solder side of the D Board printed
wiring board, the bottom plates fitted to the main chassis bracket require to be
removed.
This is performed by cutting the gates with a sharp wire cutter at the locations
indicated by arrows.
wiring board, the bottom plates fitted to the main chassis bracket require to be
removed.
This is performed by cutting the gates with a sharp wire cutter at the locations
indicated by arrows.
Note :There are 4 plates fitted to the main bracket and secured by 6 gates.
Only remove the necessary plate to gain access to the printed wiring board.
(2)
REFITTING THE PLATES
Because the plates differ in size it is important that the correct plates are refitted in
their original location.
The plates are identified by numerical markings on their top side e.g. 1,2
their original location.
The plates are identified by numerical markings on their top side e.g. 1,2
1.
Identify the plate by locating its marking.
2.
Rotate the plate through 180’ (do not flip over).
3.
Locate the corresponding numerical markings indicated on the main
chassis. See Fig 2.
chassis. See Fig 2.
4.
Refit the plate as indicated in Fig 3 with the markings located next to each
other.
other.
£
For safety reasons, on no account should the plates be
removed and not refitted after servicing.
removed and not refitted after servicing.
In the event of the plates requiring to be removed
at a later stage, this can be achieved by inserting a
screwdriver in the snap-recess indicated as in Fig 4
and lifting out.
at a later stage, this can be achieved by inserting a
screwdriver in the snap-recess indicated as in Fig 4
and lifting out.
19
•
When complete readjustment is necessary or a new
picture tube is installed, carry out the following
adjustments.
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.
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:
controls and switches to the following settings:
Contrast
...............
normal
Brightness
...............
normal
Carry out the following adjustments in this order:
3-1.
3-1.
Beam Landing
3-2.
Convergence
3-3.
Focus
3-4.
White balance
Note:
Test equipment required
1.
1.
Color bar/pattern generator.
2.
Degausser.
3.
Digital multimeter.
4.
Oscilloscope.
SECTION 3
SET-UP ADJUSTMENTS
Fig.3-1
Fig.3-2
Purity
Align Pips
on each
magnet
on each
magnet
Neck assy
Align the bottom edge
of the neck assy with
the G3 hole centre.
of the neck assy with
the G3 hole centre.
Deflection yoke
3-1. BEAM LANDING
Preparation:
1.
In order to reduce the influence of geomagnetism on the set’s
picture tube, face it in an easterly or westerly direction.
picture tube, face it in an easterly or westerly direction.
2.
Switch on the set’s power and degauss with the
degausser.
degausser.
(1)
Adjustment of Correction Magnet for Y-Splitting
Axis
Axis
1.
Input a crosshatch signal from the pattern generator.
2.
Set the Picture control to minimum and confirm that the
Brightness control is set to normal.
Brightness control is set to normal.
3.
Position the neck assembly as indicated in Fig.3-2.
4.
Move the deflection yoke as far forward as is possible.
5.
Adjust the upper and lower pin symmetrically by opening or
closing the Y-splitting axis correction magnets located on the
neck assembly.
closing the Y-splitting axis correction magnets located on the
neck assembly.
6.
Return the deflection yoke to its original position.
Caution :
High voltages are present on the Deflection yoke terminals -
take care when handling the Deflection yoke whilst carrying
out adjustments.
take care when handling the Deflection yoke whilst carrying
out adjustments.
(2) Landing
Note :Before carrying out the following adjustments
adjust the magnets as indicated below [See Fig.3-3].
1.
Input an all-white signal from the pattern generator.
Maximize the picture setting and adjust the Brightness
setting.
Maximize the picture setting and adjust the Brightness
setting.
2.
Rough-adjust the focus and horizontal convergence.
3.
Loosen the deflection yoke screws and align the purity
adjustment knob to its central position. [See Fig.3-1].
adjustment knob to its central position. [See Fig.3-1].
4.
Switch from the all-white pattern to an all-green pattern.
5.
Move the deflection yoke backwards and adjust with the
purity magnet so that the green is at the centre and it aligns
symmetrically. [See Fig.3-4].
purity magnet so that the green is at the centre and it aligns
symmetrically. [See Fig.3-4].
6.
Move the deflection yoke forward and adjust so that the
entire screen becomes green.
entire screen becomes green.
7.
Switch the raster signal to red, then to blue and verify the
landing condition.
landing condition.
8.
When the position of the deflection yoke has been determined,
fasten the deflection yoke with the screw.
fasten the deflection yoke with the screw.
9.
If the beam does not land correctly in all the corners of the
screen, use magnets to correct it. [See Fig.3-5].
screen, use magnets to correct it. [See Fig.3-5].
Y-splitting axis correction magnet
Fig.3-3
20
Fig.3-4
Fig. 3-5
3-2. CONVERGENCE
(1)
Screen centre convergence
[Static convergence]
[Static convergence]
1.
Input a dot signal from the pattern generator.
Normalize the picture setting.
Normalize the picture setting.
2.
[Moving horizontally], adjust the H.STAT control so that the
horizontal red, green and blue dots coincide at the centre of the
screen.
horizontal red, green and blue dots coincide at the centre of the
screen.
3.
[Moving vertically], adjust the V.STAT magnet so that the
vertical red, green and blue dots coincide at the centre of the
screen.
vertical red, green and blue dots coincide at the centre of the
screen.
•
If the horizontal dots are unable to coincide with the variable
range of the H.STAT convergence, adjust together with the
V.STAT convergence while tracking.
[Adjust the convergence by tilting the V.STAT convergence or
by opening and closing the V.STAT convergence.]
range of the H.STAT convergence, adjust together with the
V.STAT convergence while tracking.
[Adjust the convergence by tilting the V.STAT convergence or
by opening and closing the V.STAT convergence.]
4.
Movement of the red, green and blue dots by tilting the
V.STAT magnet and by opening or closing the V.STAT
magnet.
V.STAT magnet and by opening or closing the V.STAT
magnet.
a).
By opening or closing the V.STAT magnet, the red, green and
blue dots move as indicated below.
blue dots move as indicated below.
b).
By rotating the V.STAT magnet counter clockwise, the red,
green and blue dots move as indicated below.
green and blue dots move as indicated below.
Purity control corrects
this area.
this area.
Disk magnets or
rotatable disk
magnets correct
these areas (a-d).
rotatable disk
magnets correct
these areas (a-d).
Deflection yoke positioning
corrects these areas
corrects these areas
H.STAT
convergence
control
V.STAT
vertical static magnet
Center dot
H.STAT VR on
mount side
H.STAT convergence
(Open)
(Close)
B
G
R
B
G
R
B
G
R
GREEN
BLUE
RED
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