Sony WCS-880, Service Manual

Page: 7 / 24

7
WCS-880
4. TX Output Level Adjustment
Setting:
Procedure:
1. Solder the core wire of coaxial cable to the CP54 on TX BASE
board, and the mesh to the foot of VCO board shield case.
2. Connect BNC to the spectrum analyzer.
3. Set the
[RF CHANNEL]
switch (SW51) to
[3]
.
4. Adjust RV51 on the TX BASE board so that the value of spec-
trum analyzer becomes –1
±
2.5 dBm.
5. Change the
[RF CHANNEL]
switch (SW51) to
[2]
.
6. Confirm that the value of spectrum analyzer satisfy specified
value.
7. Change the
[RF CHANNEL]
switch (SW51) to
[1]
.
8. Confirm that the value of spectrum analyzer satisfy specified
value.
Specified values: CH-1: –1 dBm to
±
2.5 dBm
CH-2: –1 dBm to
±
2.5 dBm
CH-3: –1 dBm to
±
2.5 dBm
5. VCO Voltage Adjustment
Setting:
Procedure:
1. Connect digital voltmeter to the TP58 on TX BASE board and
the foot of VCO board shield case.
2. Set the
[RF CHANNEL]
switch (SW51) to
[3]
.
3. Adjust CT1 on the VCO board so that the value of digital volt-
meter becomes 1.6 V.
4. Set the
[RF CHANNEL]
switch (SW51) to
[1]
.
5. Confirm that the value of digital voltmeter satisfy specified
value.
6. Set the
[RF CHANNEL]
switch (SW51) to
[2]
.
7. Confirm that the value of digital voltmeter satisfy specified
value.
Specified values: CH-2: 1.4 V to
±
0.1 V
CH-1: 1.1 V to
±
0.1 V
CH-3: 1.6 V to
±
0.1 V
6. TX Modulation Sensitivity Adjustment
Setting:
Procedure:
1. Connect an AF OSC to the MIC jack (J1) on the TX BASE
board (transmitter unit).
2. Connect a 3.3 k
Ω
load to the REC OUT plug (receiver unit),
and under this condition connect to the audio analyzer.
3. Set the
[RF CHANNEL]
switch (SW51) to
[1]
.
4. Adjust RV1 on the TX BASE board (transmitter unit) so that
the value of audio analyzer becomes –50 dBV.
5. Change the
[RF CHANNEL]
switch (SW51) to
[2]
.
6. Adjust RV2 on the TX BASE board (transmitter unit) so that
the value of audio analyzer becomes –50 dBV.
7. Change the
[RF CHANNEL]
switch (SW51) to
[3]
.
8. Adjust RV3 on the TX BASE board (transmitter unit) so that
the value of audio analyzer becomes –50 dBV.
Adjustment Location: TX BASE Board (See page 8)
audio
analyzer
AF OSC
Frequency: 1 kHz
Output level: –53.7 dBV
+
–
MIC jack (J1)
TX BASE
board
receiver
unit
lead wire antenna (ANT1)
REC out plug
(P1)
spectrum analyzer
more than 1 GHz
TP54
Foot of VCO board
shield case
TX BASE
board
+
–
digital voltmeter
Set
TP58
Foot of VCO board
shield case