Sony KV-28FQ70B Service Manual ▷ View online
- 17 -
REMOVAL AND REPLACEMENT OF THE MAIN
-
BRACKET
BOTTOM PLATES.
(1) REMOVING THE PLATES
In the event of servicing being required to the solder side of the printed wiring boards, 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 the arrows.
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 the arrows.
Note : There are 2 plates fitted to the main bracket. 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.
location.
Please note that the plates need to be rotated 180 degrees from their cut position to allow the
tabs to be fitted into their catch positions.
tabs to be fitted into their catch positions.
Tab
Catch
For safety reasons, on no account should the plates be removed
and not refitted after servicing.
and not refitted after servicing.
- 18 -
•
When complete readjustment is necessary or a new picture tube
is installed, carry out the following adjustments.
is installed, carry out the following adjustments.
•
Unless there are specific instructions to the contrary, carry out
these adjustments with the rated power supply.
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
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 TV set’s power and degauss with a degausser.
(1) Adjustment of Correction Magnet for Y-Splitting 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.
Loosen the deflection yoke fixing screw.
5.
Move the deflection yoke as far forward as is possible.
6.
Adjust the upper and lower pin symmetrically by opening or
closing the Y-splitting axis correction magnets located on the
neck assembly. [See Fig 3-3]
closing the Y-splitting axis correction magnets located on the
neck assembly. [See Fig 3-3]
7.
Return the deflection yoke to its original position and re-tighten
its fixing screw.
its fixing screw.
Carry out the adjustments in the following order :
3-1.
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.
Fig.3-1
(2) Landing
Note : Before carrying out the following adjustments adjust the
magnets as indicated [See Fig.3-4].
1.
Input a crosshatch signal from the signal generator.
2.
Rough-adjust the focus and horizontal convergence.
3.
Switch from the crosshatch pattern to an all-red pattern.
4.
Move the deflection yoke backwards and adjust with the purity
magnet so that the red is at the centre and it aligns
symmetrically [See Fig.3-5].
magnet so that the red is at the centre and it aligns
symmetrically [See Fig.3-5].
5.
Move the deflection yoke forward to the point where the entire
screen just becomes red [Mark its position].
screen just becomes red [Mark its position].
6.
Move the deflection yoke further forward until the screen just
changes colour at the edges. [Mark its position]
changes colour at the edges. [Mark its position]
7.
Position the deflection yoke between the two marks indicated
above.
above.
8.
Input a crosshatch pattern from the pattern generator and rotate
the deflection yoke so that the horizontal lines are parallel with
the top and bottom of the screen.
the deflection yoke so that the horizontal lines are parallel with
the top and bottom of the screen.
9.
When the position of the deflection yoke has been determined,
fasten it with its fixing screw.
fasten it with its fixing screw.
10. Switch the pattern generator to green then blue and confirm the
purity.
11. If the beam does not land correctly in all the corners of the
screen, use disk magnets to correct it. [Confirm the corner
landing forgreen and blue]
landing forgreen and blue]
Caution :
High voltages are present on the Deflection yoke terminals - take care
when handling the Deflection yoke whilst carrying out
adjustments.
when handling the Deflection yoke whilst carrying out
adjustments.
Y-splitting axis correction magnet
Fig.3-3
Fig.3-2
Neck assy
Align the edge
of the neck assy with
the edge of the G2 grid
on the G3 side.
of the neck assy with
the edge of the G2 grid
on the G3 side.
G2
G1
G3
+
SECTION 3 SET-UP ADJUSTMENTS
3-1. Beam Landing
- 19 -
GREEN
BLUE
RED
(1) Screen centre convergence [Static convergence]
1.
Input a dot pattern signal from the pattern generator.
2.
Normalize the picture setting.
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.
3-2. Convergence
By opening or closing the V.STAT magnet, the red green and
blue dots move in the direction indicated below.
blue dots move in the direction indicated below.
Note:
Do not adjust the H.STAT by rotating the V.STAT
magnets as this can affect the focus setting.
magnets as this can affect the focus setting.
B
G
R
B
G
R
Fig.3-5
Purity magnets
Align pips on
each magnet
each magnet
Fig.3-4
Align both Purity
magnets to the vertical
position
magnets to the vertical
position
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
a
c
d
b
Disk Magnets
Center dot
R
G
B
R
G
B
C Board
RV7375 (H STAT)
H STAT Convergence
(on mount side)
H STAT Convergence
(on mount side)
H STAT
convergence
control
V.STAT Vertical Static Magnet
Purity control magnets
- 20 -
4.
Correction for HMC [Horizontal mis-convergence] and VMC
[Vertical mis-convergence] by using the BMC [Hexapole]
magnet.
[Vertical mis-convergence] by using the BMC [Hexapole]
magnet.
a). HMC correction by BMC [Hexapole] magnet and movement of
the electron beam.
b). VMC correction by BMC [Hexapole] magnet and movement of
the electron beam.
Adjust the HAMP using HAMPL and HAMPR registers in the
Dynamic Convergence section of the service menu.
Dynamic Convergence section of the service menu.
HTIL correction can be performed by adding a THL correction
assembly to the Deflection yoke.
assembly to the Deflection yoke.
C < D
C = D
C > D
C = D
R
G
G
B
C
D
C
D
R
G
B
R
G
B
R
G
B
V M C c o r r e c t i o n ( A )
V M C c o r r e c t i o n ( B )
THL Correction assy
HAMP Adjustment
HTIL Adjustment
YCH Adjustment
H M C c o r r e c t i o n ( A )
H M C c o r r e c t i o n ( B )
A < B
A = B
R G
B
R G B
A > B
A = B
R
G B
R G B
TLV Adjustment
H-TRAP Adjustment
The H-TRAP should not be adjusted unless absolutely necessary as it
affects the TLV settings.
affects the TLV settings.
+
+
+
YCH VR
Deflection Yoke
+
+
+
TLV VR
Deflection Yoke
HTRAP VR
+
+
+
Deflection Yoke
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