Sony XR-4790 Service Manual

– 16 –
TUNER SECTION
FM Noise Focus Adjustment
Setting:
[SOURCE] button: FM
FREQUENCY SELECT switch: 10 k
Procedure:
1. Tune the 97.9 MHz.
2. The then output level is supposing that (A) dB.
3. Adjust with the volume RV3 on TU1 so that the output level is
(A) –32 ± 2 dB then signal generator input set to –20 dB.
Adjustment Location: See page 18.
FM Stereo Separation Adjustment
Setting:
[SOURCE] button: FM
FREQUENCY SELECT switch: 10 k
Procedure:
FM Stereo
Level meter Level meter
signal generator
connection reading (dB)
output channel
L-CH L-CH A
B
R-CH L-CH Adjust RV4 on TU1
for minimum reading.
R-CH R-CH C
D
L-CH R-CH Adjust RV4 on TU1
for minimum reading.
L-CH Stereo separation: A-B
R-CH Stereo separation: C-D
The separations of both channels should be equal.
Specification: Separation more than 30 dB
Adjustment Location: See page 18.
97.9
SHUF1
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 Noise Focus Adjustment
3. FM Stereo Separation Adjustment
4. AM (MW) Auto Scan/Stop Level Adjustment
FM Auto Scan/Stop Level Adjustment
Setting:
[SOURCE] button: FM
FREQUENCY SELECT switch: 10 k
Procedure:
1. Set to the test mode. (See page 15).
2. Push the [SOURCE] button and set to FM.
Display
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
Adjustment Location: See page 18.
FM RF signal
generator
Carrier frequency : 97.9 MHz
Output level : 22 dB (12.6
µ V)
Mode : mono
Modulation : 1 kHz, 22.5 kHz deviation (30%)
0.01 µ F
set
antenna jack (J1)
FM RF signal
generator
Carrier frequency : 97.9 MHz
Output level : 60 dB (1 mV)
Mode : mono
Modulation : 1 kHz, 75 kHz deviation (100%)
0.01 µ F
set
antenna jack (J1)
+
–
LINE OUT
level meter
10 k
Ω
FM RF signal
generator
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%)
0.01 µ F
set
antenna jack (J1)
+
–
LINE OUT
level meter
10 k
Ω
FM
97.9
SHUF1
(4800: E model only)
0 dB=1 µV
XR-4790 and XR-4800 US/Canadian model, a tuner section is no
adjustment.

Sony XR-4790 Specifications

General

Brand	Sony
Model	XR-4790
Category	Car Receiver
Language	English