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Preparation for VCO Adjustment
1.
Connect the measuring equipment to the TV as shown in Fig. 1.
2. Set RF output level of sweep S.G.(Signal Generator) to 80dBuV.
3. Set Alignment Scope, Volts/Div to 100mV, AC/DC switch to
AC, Line/Ext switch to Ext.
38.9MHz
Signal
generator
GND
12Vdc
Power
Supply
GND(C26(-))
* VCO (Voltage Controlled Oscillation) Adjustment
a) For B/G system
Test Poin t
Adjust
1)
Turn on DC power supplies.
2) Adjust VCO adjust coil(L107)so that DMM reads 2.5Vdc+_0.1V.
Ceramic
CAP.
10000pF
3
4
Ceramic
CAP.
10000pF
C25(+)
C25(-)
Fig.1: Connection Diagram of Equipment for BG VCO Adjustment
Pin 24 of IC101 (+ lead of C123)
:
: L107
MAIN BOARD
IC101
TDA4474
Z101
L107
5
G3962
C123(+)
24
J77
J169
R139
R124
Multimeter &
oscilloscope
2.5Vdc
5V
SW1
AM/FM SW
GND
SW2
L/L'SW
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