Sony SPP-874, Service Manual, Page: 19 / 38

0 V
Adjust so that they
synchronize at 0 V.
RSSI output waveform RF signal EXT
signal 20 Hz
RSSI WAVEFORM
+
–
level meter
TP23 (SP)
TP22 (SP)
+
–
digital voltmeter
TP8 (RX VT)
TP4 (GND)
RV101
L101
L3
RV1
TP23
TP1
TP4
TP22
TP8
TP103
TP36
TP27
50
Ω
L4
– 19 – – 20 –
HANDSET SECTION
Note:
• Apply 4V dc from regurated DC power supply.
• Perform the adjustment at T1CH (26CH : 43.780 MHz) as a rule.
• Set to handset machine test mode. (Refer to page 14.)
TX SECTION ADJUSTMENT
TX VT Adjustment
Setting :
Procedure :
1. The digital voltmeter connected TP103 (TX VT) to TP4 (GND).
2. Adjust the L101 for 1.0
±
0.1V reading on the digital voltmeter.
RX VT Adjustment
Setting :
Procedure:
1. The modulation analyzer connected TP1 to TP4 (GND).
2. Adjust the RV101 for 2.0
±
0.5 mW reading on the modulation
analyzer.
Procedure :
1. Adjust the L4 for the maximam reading on the level meter.
Also check that the output level is the specified values.
Specified Value : –8.6 to –16.6 dBV
RSSI Hi Adjustment
Note:
• Perform the adjustment at T1CH (26CH : 43.780 MHz) as a rule.
Setting :
Procedure :
1. The digital voltmeter connected TP8 (RX VT) to TP4 (GND).
2. Adjust the L3 for 3.2
±
0.1 V reading on the digital voltmeter.
RX SECTION ADJUSTMENT
Power Level Adjustment
Note:
• Connect a resistor of 50
Ω
between TP1 and TP4 on Hand main
board before adjustment.
After adjustment, remove the resistor.
Setting:
Procedure :
1. Use the oscilloscope to confirm the FM RF signal generator
input (AF) signal waveform and RSSI signal, and use the RV1
so that they are synchronized (duty is synchronized).
Carrier frequency : 43.780 MHz
Modulation
: 1 kHz
Deviation : FM 3 kHz
Output level : 60 dB
µ
V (1 mV) (EMF)
RX DISCRI Adjustment
Note:
• Perform the adjustment at T1CH (26CH : 43.780 MHz) as a rule.
Setting :
Carrier frequency : 43.780 MHz
Modulation
: 20 Hz (EXT)
Deviation : AM 50%
Output level : 0 dB
µ
V (1
µ
V) (EMF)
Adjustment Location :
– hand main board (side A) –
– hand main board (side B) –
+
–
digital voltmeter
TP103 (TX VT)
TP4 (GND)
+
–
modulation
analyzer
TP1
TP4 (GND)
FM RF
signal generator
TP1
TP4 (GND)
FM RF
signal generator
TP1
TP4 (GND)
AF oscillator
Output: 20 Hz
+
–
oscilloscope
(DC range)
TP27 (SIG IN)
TP4 (GND)
Adjustment Location : hand main board (See page 20).