Sony SPP-A946, Service Manual

Page: 21 / 56

– 21 –
SECTION 4
ELECTRICAL ADJUSTMENTS
• Make the set in test mode. (See page 16)
• Remove the solder of the BP (ANT) on the BASE MAIN board
when performing adjustments. After completing the adjustments,
short the BP (ANT) by solder.
– TX Adjustments –
1. TX Power Adjustment
Setting:
Procedure:
1. Connect a power meter to TP (ANT) and TP (GND) on the
BASE MAIN board.
2. Adjust RT301 on the BASE RF board (the BASE RF board is
mounted on the BASE MAIN board) so that the value of power
meter becomes –5 dBm.
2. TX Frequency Adjustment
Setting:
Procedure:
1. Connect a frequency counter to TP (ANT) and TP (GND) on
the BASE MAIN board.
2. Adjust CT1 on the BASE MAIN board so that the value of
frequency counter becomes 926.897468 MHz.
3. Modulation Sensitivity Adjustment
Setting:
Procedure:
1. Connect an AF OSC to the LINE jack (J1) on the BASE MAIN
board.
2. Connect a deviation meter to TP (ANT) and TP (GND) on the
BASE MAIN board.
3. Set the
[DIAL MODE]
switch (S2) to the
[PULSE]
position.
4. Press the
[INTERCOM]
key once to change the test mode step
to TX MOD CHECK.
5. Adjust RT3 on the BASE MAIN board so that the value of
deviation meter becomes
±
8 kHz deviation.
0 dBm = 0.775 V, 0 dBV = 1 V
BASE UNIT
+
–
power meter
TP (ANT)
TP (GND)
+
–
frequency counter
TP (ANT)
TP (GND)
AF OSC
1 kHz, –20 dBm
+
–
600
Ω
LINE jack (J1)
+
–
deviation meter
TP (ANT)
TP (GND)
– RX Adjustments –
1. DISCRI Voltage Adjustment
Setting:
Procedure:
1. Connect a SSG to TP (ANT) and TP (GND) on the BASE
MAIN board.
2. Connect a digital voltmeter to TP (DISCRI) and TP (GND) on
the BASE MAIN board.
3. Set the
[DIAL MODE]
switch (S2) to the
[PULSE]
position.
4. Press the
[INTERCOM]
key three times to change the test mode
step to RX SENS.
5. Adjust L3 on the BASE MAIN board so that the value of digi-
tal voltmeter becomes 1 V.
2. TEL Out Level Adjustment
Setting:
Procedure:
1. Change the modulation of SSG to 1 kHz,
±
8 kHz deviation.
2. Connect a noise meter to the LINE jack (J1) on the BASE
MAIN board.
3. Adjust RT2 on the BASE MAIN board so that the value of
noise meter becomes –8.5 dBm.
SSG
Carrier frequency: 902.902467 MHz
Modulation: no modulation
Output level: – 47 dBm
TP (ANT)
TP (GND)
+
–
digital voltmeter
TP (DISCRI)
TP (GND)
SSG
Carrier frequency: 902.902467 MHz
Modulation: 1 kHz,
±
8 kHz deviation
Output level: – 47 dBm
TP (ANT)
TP (GND)
noise meter
600
Ω
+
–
LINE jack (J1)