Tuner Section - Sony XR-4880 Service Manual

TUNER SECTION

Cautions during repair
When the tuner unit is defective, replace it by a new one be-
cause its internal block is difficult to repair.
Note:
Adjust the tuner section in the sequence shown below.
1. FM Auto Scan/Stop Level Adjustment.
2. FM Stereo Separation Adjustment.
3. MW Auto Scan/Stop Level Adjustment.
FM Auto Scan/Stop Level Adjustment
Setting:
[SOURCE]
button: FM
FM RF signal
generator
0.01 µ F
Carrier frequency : 98.0 MHz
: 22 dB (12.6 µ V)
Output level
Mode : mono
Modulation : 1 kHz, 22.5 kHz deviation (30%)
Procedure:
1. Set to the test mode. (See page 13).
[SOURCE]
2. Push the button and set to FM.
Display
FM
SHUF1
3. Adjust with the volume RV2 on TU1 so that the "FM" indica-
tion turns to "FMI" indication on the display window.
But, in case of already indicated "FMI", turn the RV2 so that
put out light "I" indication and adjustment.
Display
FM
SHUF1
Adjustment Location: See page 16.
0 dB=1 µV
antenna jack (J1)
set
98. 0
98. 0
FM Stereo Separation Adjustment
Setting:
[SOURCE]
button: FM
FM RF signal
antenna jack (J1)
generator
0.01 µ F
Carrier frequency : 98.0 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
signal generator
output channel
L-CH
R-CH
R-CH
L-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 28dB
Adjustment Location: See page 16.
– 14 –
level meter
4 Ω
set
speaker out terminal
Level meter Level meter
connection reading (dB)
A
L-CH
B
L-CH Adjust RV4 on TU1
for minimum reading.
C
R-CH
D
R-CH Adjust RV4 on TU1
for minimum reading.
+
–