Electrical adjustments
Setting conditions
All electrical settings should be made under the
following conditions:
l
supply voltage: 220 240 V 10%;
50
Hz 5%
l
warming-up time 10 minutes
the voltages and oscillograms have been
measured with regard to tuner earth.
l
measuring probe: Ri 10
Ci 2.5
1. Settings on the carrier board
1 . 1
1.2
1.3
1 . 4
1.5
1.6
1.7
1.8
a .
+
+ 95V supply voltage
Connect a voltmeter over
Using R3635,
set the‘supply voltage to + 148V
for 25”
and 28” units or to 95V
for
units.
Focusing
This is set using the focusing potentiometer (on the
top of the line output transformer).
Vg2 setting
Connect a pattern generator and supply a blanking
frame signal (black picture). Switch the unit to the
service default mode (see section 9).
Connect an oscilloscope to the emitters of
transistors 7304 and 7364 on the picture tube
module. Set the oscilloscope to frame frequency.
Measure the DC voltage level of the measuring
pulses (see Fig. 7.2). Using the Vg2 potentiometer
on the line output transformer, set the measuring
pulse with the lowest DC voltage level to:
+ 145V 5V for 25” and 28” blackline units
(protected
cable)
130V 5V for 28” non-blackline units
+
5V for 25” non-blackline units
+
5V for 21” units.
Horizontal synchronization
Connect pin
to pin
Supply an aerial signal and tune the set.
Adjust potentiometer 3457 until the picture is
straight. Remove the interconnection.
Horizontal
Set using potentiometer 3461.
Vertical
Set using potentiometer 35 16.
Picture height
Set using potentiometer 3504.
Chroma
filter
Setting for
sets
Connect a signal generator (e.g. PM 5326) to
pin 20 of the euroconnector
and set its
frequency to 4.286
Vpp. Switch the unit
to
Connect pin
to pin
12V). Connect an oscilloscope to pin
Set 5301 to maximum amplitude.
Remove the interconnection.
b .
1.9
1 . 1 0
1.11
1 . 1 2
1 . 1 3
1 . 1 4
Setting for PAL sets
Connect a signal generator (e.g. PM 5326) to
pin 20 of the euroconnector
and set its
frequency to 4.43 MHz. Connect the unit to
Connect an oscilloscope to pin
5301 to maximum amplitude.
Chroma auxiliary oscillator
Connect a pattern generator and supply
a
PAL
colour bar pattern. Connect pin 1
or pin
to earth.
Set 2313 so that the colour on the screen has
practically stopped. Remove the interconnection.
SECAM demodulators for
sets
Connect a pattern generator and supply a SECAM
black pattern. Connect an oscilloscope to pin
Set 5304 to minimum
amplitude.Connect the oscilloscope to
pin
Set 3312 to minimum
amplitude.
White balance
Connect a pattern generator and select a white
picture. Switch on the service menu (see section
and select “WHITE BALANCE”.
Set the value of “Green” to 51, and the Value of
“Blue” to 46. In most cases-no futher adjustments
are required.
Peak white limit
Switch on the service menu (see section 9) and
select WHITE BALANCE”.
Set “WHITE LIMIT” to the value:
43 for blackline units
53 for non-blackline units
53 for 21 units.
Cut-off points of the picture tube
Connect a pattern generator and select a black
picture. Switch on the service menu (see section
and select “CUT OFF”.
Set the value of “Red” to 56, and fore “Green”
to 16, and for “Blue” to 15. In most cases no
futher adjustments are required.
Options
Switch on the service menu and select
“OPTION 1” or “OPTION 2”.
Switch the options “ON” and “OFF” according to
whether the following options are present:
“PIP” on a PIP set
SCART” on a set with two
euroconnectors
“TELETEXT” on a teletext set
for the Y/C connector in mono sets
“MULTI SYSTEM”
for multisystem sets
“HYPERBAND” for a tuner which can be tuned
to the frequency band of 300 MHz to 450 MHz
“UHF ONLY” for a tuner which can only be
tuned to the UHF band
“NICAM TWIN” for stereo sets which can also
receive NICAM sound.
“SIXTEEN/NINE” for switching between normal
screen size and wide screen size.
