@CAUTION
1)
Safety requirements stipulate that, during repair, the
set should be restored
to
its original state and
that
parts indentical
to
the specified ones, should be
applied.
2)
For safety reasons, the parts indicated with the sign
A should be replaced by identical parts (for code
numbers see electrical parts
lists).
3)
To avoid damage to ICs and transistors, flash-over
of
the high-tension should be avoided.
4)
Be careful when performing measurements in the
high-tension section and on the picture tube.
5)
Never change parts when the set is still switched on.
6)
Safety goggles must be worn during replacement
of
the picture tube.
ELECTRICAL ADJUSTMENTS
1.
ADJUSTMENTS
ON
THE CHASSIS
1.1
+128V supply voltage (3414)
- Apply video signal to the monitor.
-
Set volume control 3295, brightness control 3662 and
contrast control 3658
to
minimum.
-
Set trimming potentiometer 3414
in
mid-position.
(This is a presetting).
- Connect
DC
voltmeter
to
junction
of
resistor 3520 and
diode 6453.
- Switch on monitor.
- With trimming potentiometer 3414 set the
DC
voltage
at junction 3524/6453 to
128V.
1.2 Horizontal synchronization (3257)
- Apply video signal
(cross-hatch
pattern) to the monitor.
- Short capacitor
2270. (This capacitor is connected
to
pin 5
of
IC
7270.)
- With trimming potentiometer 3257, adjust the picture
so that it
is
straight.
- Remove the
short-circuit
on 2270.
1.3 Picture position
General: For the following adjustments apply a video
signal
(cross-hatch
pattern) to the monitor.
1.3.1
East-west
correction (3537)
- With potentiometer 3537, make the vertical lines on
the left and
right-hand
side
of
the screen as straight
as possible.
1.3.2 Picture width (3534)
- With potentiometer 3534, set the picture width
for
14
blocks to
260 mm.
1.3.3 Horizontal picture centering (3264)
- With potentiometer 3264, set the correct horizontal
centering.
1.3.4
Vertical picture centering (3583)
- With potentiometer 3583, set the correct vertical
picture centering.
1.3.5 Picture height
(3550)
- With potentiometer 3550, set the picture height
for
1 0
blocks to 186 mm.
1.3.6.
Vertical linearity (3573)
- Adjust the correct vertical linearity with
Pre-set
potentiometer 3573. If necessary repeat 1.3.5 and
1.3.6.
1.4
Setting
of:
• VG2 (bottom knob on the line output transformer)
•
cut-off
points
of
the picture tube
(31
07, 3117 and 3127)
• white
"D"
(3671, 3680)
Set
the brightness
to
1/4
of
its range and set the
contrast to minimum.
Set the potentiometers
3107,3117,3127,3671
and
3680
in
mechanical
mid-position.
Set VG2 potentiometer
to
minimum.
Set the signal generator
in
"pur" position and
introduce the respective colours red, green and blue.
- Using potentiometers
3107, 3117 and 3127 with the
corresponding colour pattern, set the voltage on the
picture tube pins
8,
6 and
11
to
1
OOV.
- Apply a white frame and adjust the VG2 potentiometer
so
that
any colour among red, green
or
blue
becomes
visible.
-
Set the pattern generator
to
purity with
the
colour that
was
first visible.
- Reset
VG2 potentiometer
to
just
visible light.
- Adjust the
two
remaining colours with
their
corresponding purity colour
to
the same light
output
using potentiometers
31
07, 3117
or
3127.
- Return the signal generator
to
white
frame
and adjust
the potentiometers
3107,3117
and 3127
so
that
an
optimum background colour is obtained.
- Using potentiometers 3671 and
3680 (with white
frame) adjust the background colour
so
that
at
minimum brightness and maximum brightness the
background colour is the same.
1.5 Focusing (top knob
on
line output transformer)
- Apply white pattern to monitor.
- Adjust focusing so that the picture
at
2/3
of
the
diagonal lines (counting from center
to
four
corners)
of
the displayed screen is as sharp as
possible.
1.6 Subcarrier oscillator (2613)
- Apply colour bar pattern
to
monitor.
- Connect
470Q resistor between point
11
of
IC
761
0
and earth.
- Adjust 2613 so that the colour picture
on
the screen is
stationary.
- Remove the
470Q resistor.
1.7 PAL delay line (3619, 5632)
-
Apply
OEM pattern from a pattern
generator
to
the
monitor.
Set brightness control 3662,
contrast
control
3658 and
colour
saturation control 3654 to
3/4
of
the
range.
Adjust 3619
so
that the "venetian blinds"
in
the
third
bar
disappear.
Then adjust 5632 until the
"venetian
binds"
in
the first
and fourth
bar
disappear.
Readjust 3619 as described above.
1.8 Chrominance suppression
(5605)
- Apply colour bar pattern to the monitor.
- Connect oscilloscope
to
pin 15
of
IC 7540.
- Set 5605
so
that the chrominance
sig~al
is
minimum.
(The chrominance signal
is
superimposed
on the
grey
steps
of
the luminance signal).
1.9 Audio balance (3298)
- Apply sinusoidal signal
of
177mVrms
11
K
tlz)
to
both
audio inputs LfR.
-
Set volume control
in
mid-position.
- Replace the
two
loudspeakers with a
160
resistor.
-
Set 3298 so
that
the
output
level on
b~th
16Q
resistors is the same.
cs
30
396
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