Sony SPP-A400 - Cordless Telephone With Answering Machine, Service Manual

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2. Confirmation of distortion factor
Setting:
Precedure:
• Measure the distortion factor with an audio analyzer to confirm
that it is below 2.8 %.
3. Confirmation of RX gain
Setting:
Precedure:
• Measure the distortion factor with an audio analyzer to confirm
that it is below –10 dB.
4. Adjustment of RSSI (H) gain
Setting:
Precedure:
• Observing RSSI signal with an oscilloscope, adjust RV101 so
that the duty became 50 %.
5. Adjustment of RSSI (L) gain
Setting:
Precedure:
• Press
[5]
key to set the RSSI gain of the Handset to “Low”.
• Observe the RSSI signal with an oscilloscope to confirm that the
RSSI gain is “Low”.
• Change RF output of the SG to 18 dBµV EMF, then observe the
RSSI signal with an oscilloscope to confirm that the RSSI gain is
“High”.
SG
ANTENNA TERMINAL
TP3 (RF GND)
Frequency : 43.780 MHz
RF output
: 60 dB
µ
V EMF
Signal : 1 kHz INT
Deviation : FM 3 kHz DEV
+
–
Audio analyzer
MEAS. mode : Distortion
Input range
: – 10 dBV, 3%
Filter : 400 Hz>, <20 kHz
TP47 (RX)
TP30 (GND)
+
–
Audio analyzer
MEAS. mode : Distortion
Input range
: – 10 dBV, 3%
Filter : 400 Hz>, <20 kHz
TP47 (RX)
TP30 (GND)
+
–
TP8 (RSSI)
TP30 (GND)
oscilloscope
ANTENNA TERMINAL
TP3 (RF GND)
Frequency : 43.780 MHz
RF output
: 39 dB
µ
V EMF
Signal : 1 kHz INT
Deviation : FM 3 kHz DEV
SG
+
–
TP8 (RSSI)
TP30 (GND)
oscilloscope
AF oscillator
ANTENNA TERMINAL
TP3 (RF GND)
20 Hz
SG
Frequency : 43.780 MHz
RF output : 3 dB
µ
V EMF
Signal : 20 Hz EXT
Deviation : AM50% MOD
SG
ANTENNA TERMINAL
TP3 (RF GND)
Frequency : 43.780 MHz
RF output
: –5 dB
µ
V EMF
Signal : 1 kHz INT
Deviation : FM 3 kHz DEV