Tuner Section - Sony WX-C55 Service Manual

TUNER SECTION

0 dB = 1 µV
Cautions during repair
When the tuner unit is defective, replace it by a new one because
its internal block is difficult to repair.
Note on Adjustment
The adjustments of tuner section, should be performed according
to the following sequence.
1. FM Auto Scan/Stop Level Adjustment
2. FM Stereo Separation Adjustment
3. AM Auto Scan/Stop Level Adjustment
FM Auto Scan/Stop Level Adjustment
Setting :
SOURCE button
FREQUENCY SELECT switch (E model) : FM 200k
FM RF signal
generator
Carrier frequency : 97.9 MHz
Output level : 22 dB (12.6 µV)
Mode : mono
Modulation : 1 kHz, 22.5 kHz deviation (30%)
Procedure :
1. Set to the test mode.
2. Push the SOURCE button and set to FM.
Display
SHUF1
3. Push the preset 3 button.
Display
SHUF1
4. Adjust with the volume RV2 on TU1 so that the "FM"
indication turns to "2" indication on the display window.
But, in case of already indicated "2", turn the RV2 so that put
out light "2" indication and adjustment.
Display
SHUF1
Adjustment Location : See page 23.
: FM
antenna
terminal
0.01 µ F
set
PRESET
PRESET
FM Stereo Separation Adjustment
Setting :
SOURCE button
FREQUENCY SELECT switch (E model) : FM 200k
FM RF signal
generator
antenna
terminal
0.01 µ F
Carrier frequency : 97.9 MHz
Output level : 70 dB (3.2 mV)
Mode : stereo
Modulation : main :1 kHz, 33.75 kHz deviation (45%)
sub :1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot : 7.5 kHz deviation (10%)
Procedure :
FM stereo
Level meter
signal generator
connection
output channel
L-CH L-CH
R-CH L-CH
R-CH R-CH
L-CH R-CH
L-CH stereo separation : A – B
R-CH stereo separation : C – D
The separations of both channels should be equal.
Specification : Separation more than 28 dB
Adjustment Location : See page 23.
: FM
level meter
10 k Ω
set
AUDIO OUT REAR
Level meter
reading (dB)
A
B
Adjust RV4 on TU1 for
maximum reading.
C
D
Adjust RV4 on TU1 for
maximum reading.
21