Electrical Adjustmens - Sony ICF-SC1 Service Manual

Setting :
trackig generator
spectrum analyzer
FM RF signal
generator
digital
voltmeter
(GND)
RF BOARD (SINGLE) ADJUSTMENT
1. 2nd local oscillator Adjustment
Procedure :
(1) Connect a tracking generator to TP10 and a spectrum ana-
lyzer to TP6.
(TG level = – 40 to – 50dBm, spectrum analyzer span =
200MHz)
(2) Receive a 600MHz signal.
(3) Repeatedly adjust CT303, 304 and 305 for an optimal wave-
form at center frequency of 277.5MHz.
(4) Receive the 25MHz signal.
(5) Adjust the 2nd local oscillator to 555MHz with CT302.
(spectrum analyzer span = 10kHz)
2. 1st local oscillator Adjustment
Procedure :
(1) Connect a spectrum analyzer to TP5.
(2) Receive a 767.5MHz signal.
(3) Adjust the CT301 so that 1st local oscillator = 1000MHz
(spectrum analyzer span = 10kHz)
3. 1st IF (low) Adjustment
Procedure :
(1) Connect a tracking generator to TP5 and a spectrum analyzer
to TP7.
(2) Recive a 500MHz signal.
(3) Repeatedly adjust CT201, 202 and 203 for an optimal wave-
form (ladder shape) at center frequency of 232.5MHz.
(TG level = – 30 to – 40dBm, spectrum analyzer span =
200MHz)
Adjustment Location : RF board (see page 14)
SECTION 4
ELECTRICAL ADJUSTMENTS
(GND)
(GND)
(GND)
IF BOARD (SINGLE) ADJUSTMENT
1. 3rd local oscillator Adjustment
Procedure :
(1) Connect a spectrum analyzer to TP2.
(2) Receive a 49.975MHz signal.
(3) Adjust the CT401 so that the 3rd local oscillator =
44.5500MHz. (spectrum analyzer span = 10kHz)
(4) Recive a 50.0125MHz signal.
(5) Adjust the 3rd local oscillator to 44.5425MHz with RV401.
(spectrum analyzer span = 10kHz)
Adjustment Location : IF board (see page 14)
RF & IF BOARD (COMBINATION) ADJUSTMENT
1. 2nd IF (narrow) Adjustment
Procedure :
(1) Connect a tracking generator to RF (RF board) TP6 and con-
nect a spectrum analyzer to IF (IF board) TP1 by way of a
0.5pF capacitor.
(2) Receive a 29MHz signal.
(3) Align for an optimal waveform with T206.
(ladder waveform with minimum ripple)
(TG level = – 50dBm, spectrum analyzer Center freq. =
45MHz, span = 100kHz)
2. 2nd IF (wide) Adjustment
Procedure :
(1) Connect a tracking generator to RF (RF board) TP6 and con-
nect a spectrum analyzer to IF (IF board) TP3.
(2) Receive a 70MHz signal.
(3) Adjust so the 45MHz is at maximum by using CT402 and
T205.
(TG level = – 50dBm, spectrum analyzer Center freq. =
45MHz, span = 50MHz)
3. AGC Adjustment
Procedure :
(1) Connect a FM RF signal generator to the BNC (ANT IN)
connector.
(2) Connect a digital voltmeter to RV403 center tap (COMMON).
(3) Receive a 122MHz signal (input level 80d
lation 30%).
(4) Adjust RV403 so that digital voltmeter reading is at 1.68
0.02V.
Adjustment Location : RF, IF board (see page 14)
* Use semirigid cable when connecting the tracking generator and
spectrum analyzer to the circuit board.
* Spectrum analyzer settings shown in the ( ) are reference values.
– 13 –
(IF board)
µEMF, AM, modu-
±