Electrical Adjustments - Sony SRF-M73 Service Manual

0 dB = 1 µV
[AM]
Setting:
Band switch: AM
Put the lead-wire
AM RF signal
antenna close to
generator
the set.
30% amplitude
modulation by
400 Hz signal
Output level: as low as possible
[FM]
Setting:
Band switch: FM
FM RF signal
generator
0.01 µ F
22.5 kHz frequency
deviation by 400 Hz
signal
Output level: as low as possible
• Repeat the procedures in each adjustment several times, and the
tracking adjustments should be finally done by the trimmer ca-
pacitors.
digital voltmeter
MAIN board
TP (VT)
+
–
Adjustment Location: Main Board (See page 7)
SECTION 4

ELECTRICAL ADJUSTMENTS

level meter
32 Ω
+
set
–
2 jack (J1)
MAIN board
level meter
TP (FM IN)
32 Ω
+
set
–
2 jack (J1)
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter
T1
AM VCO VOLTAGE ADJUSTMENT
Adjustment Part Frequency Display
L4 530 kHz (531 kHz)
Confirmation 1710 kHz (1602 kHz)
AM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L1
CT1
FM VCO VOLTAGE CONFIRMATION
Frequency Display
87.5 MHz
108 MHz
FM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L2
CT2
( ): Panama model
FM Free-Run Adjustment
Setting:
FM RF signal
generator
Carrier frequency : 98 MHz
Modulation
Output level
Procedure:
1. Connect the frequency counter to TP (MPX) as shown the fig-
ure below.
2. Tune the set to 98 MHz.
3. Adjust RT1 for 76 kHz reading on the frequency counter.
Specification: 75.8 kHz to 76.2 kHz
MAIN board
TP (MPX)
Adjustment Location: MAIN board (See page 7)
– 6 –
450 kHz
Reading on Digital Voltmeter
3 ± 0.1V
9 ± 1V (8.5 ± 1V)
580 kHz (621 kHz)
1,490 kHz (1,395 kHz)
Reading on Digital Voltmeter
3 ± 0.3V
Less than 11 ± 1V
87.5 MHz
108 MHz
MAIN board
TP (FM IN)
0.01 µ F
set
: no modultion
: 0.1 V (100 dB)
frequency
counter
1 µ F
+
+
–