Sony CDX-C7850 Service Manual ▷ View online
– 17 –
6
chassis (OP) (O/S) assy
7
compression spring (FL)
4
Fit lever (D) in the
direction of the arrow.
3
damper (T)
2
damper (T)
5
Turn loading ring in the
direction of the arrow.
1
tension spring (angle)
8
compression spring (FL)
1
P 2x3
2
sled motor assy
3
optical pick-up block
2-11. CHASSIS (OP) (O/S) ASSY
2-12. OPTICAL PICK-UP BLOCK
– 18 –
SHUF
SHUF
SHUF
FM RF signal
generator
generator
antenna
terminal
terminal
0.01
µ
F
set
SECTION 3
ELECTRICAL ADJUSTMENTS
Carrier frequency : 97.9 MHz
Output level
Output level
: 22 dB (12.6
µ
V)
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.
1. Set to the test mode.
2. Push the SOURCE button and set to FM.
Display
FM Auto Scan/Stop Level Adjustment
Setting :
SOURCE button : FM
3. Push the preset 3 button.
Display
4. Adjust with the volume RV2 on TU10 so that the “FM”
indication turns to “FM0” indication on the display window.
But, in case of already indicated “FM0”, turn the RV2 so that
put out light “0” indication and adjustment.
But, in case of already indicated “FM0”, turn the RV2 so that
put out light “0” indication and adjustment.
Display
CD SECTION
CD section adjustments are done automatically in this set.
TUNER SECTION
Cautions during repair
When the tuner unit is defective, replace it by a new one
because its internal block is difficult to repair.
because its internal block is difficult to repair.
TEST MODE
This set have the test mode function. In the test mode, FM Auto
Scan/Stop Level and AM Auto Scan/Stop Level adjustments can be
performed easier than it in ordinary procedure.
Scan/Stop Level and AM Auto Scan/Stop Level adjustments can be
performed easier than it in ordinary procedure.
<Set the Test Mode>
1. Set the “OFF” mode.
2. Push the preset 4 button.
3. Push the preset 5 button.
4. Press the preset 1 button for more than two seconds.
5. Then the display indicates all lights, the test mode is set.
1. Set the “OFF” mode.
2. Push the preset 4 button.
3. Push the preset 5 button.
4. Press the preset 1 button for more than two seconds.
5. Then the display indicates all lights, the test mode is set.
<Release the Test Mode>
1. Push the OFF button.
1. Push the OFF button.
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 (WIDE)
3. FM Stereo Separation Adjustment (NARROW)
4. AM Auto Scan/Stop Level Adjustment
to the following sequence.
1. FM Auto Scan/Stop Level Adjustment
2. FM Stereo Separation Adjustment (WIDE)
3. FM Stereo Separation Adjustment (NARROW)
4. AM Auto Scan/Stop Level Adjustment
0 dB = 1
µ
V
Adjustment Location : See page 20.
– 19 –
FM RF signal
generator
generator
antenna
terminal
terminal
set
level meter
10 k
Ω
LINE OUT REAR
0.01
µ
F
FM RF signal
generator
generator
antenna
terminal
terminal
set
level meter
10 k
Ω
LINE OUT REAR
0.01
µ
F
FM Stereo Separation Adjustment (WIDE)
Setting :
SOURCE button : FM1
Carrier frequency : 97.9 MHz
Output level
Output level
: 70 dB (3.2 mV)
Mode
: stereo
Modulation
: main : 1 kHz, 33.75 kHz deviation (45%)
sub
sub
: 1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot : 7.5 kHz deviation (10%)
FM stereo
Level meter
Level meter
signal generator
connection
reading (dB)
output channel
L-CH
L-CH
A
B
R-CH
L-CH
Adjust RV3 on TU10 for
minimum reading.
minimum reading.
R-CH
R-CH
C
D
L-CH
R-CH
Adjust RV3 on TU10 for
minimum reading.
minimum reading.
L-CH stereo separation : A – B
R-CH stereo separation : C – D
The separations of both channels should be equal.
R-CH stereo separation : C – D
The separations of both channels should be equal.
Specification : Separation more than 24 dB
Adjustment Location : See page 20.
Procedure :
FM Stereo Separation Adjustment (NARROW)
Setting :
SOURCE button : FM1
Carrier frequency : 97.9 MHz
Output level
Output level
: 70 dB (3.2 mV)
Mode
: stereo
Modulation
: main : 1 kHz, 33.75 kHz deviation (45%)
sub
sub
: 1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot : 7.5 kHz deviation (10%)
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 TU10 for
minimum reading.
minimum reading.
R-CH
R-CH
C
D
L-CH
R-CH
Adjust RV4 on TU10 for
minimum reading.
minimum reading.
L-CH stereo separation : A – B
R-CH stereo separation : C – D
The separations of both channels should be equal.
R-CH stereo separation : C – D
The separations of both channels should be equal.
Specification : Separation more than 18 dB
Adjustment Location : See page 20.
Procedure :
1. Push the SHIFT button.
2. Push the 4 button three times.
3. Push the 5 button twice and set to NARROW mode.
1. Push the SHIFT button.
2. Push the 4 button three times.
3. Push the 5 button twice and set to NARROW mode.
– 20 –
TU10
RV1
AM AUTO SCAN/
STOP LEVEL ADJ
RV2
FM AUTO SCAN/
STOP LEVEL ADJ
RV3
FM STEREO
SEPARATION ADJ
(WIDE)
RV4
FM STEREO
SEPARATION ADJ
(NARROW)
TP
SHUF
TP
SHUF
TP
SHUF
AM RF signal
generator
generator
antenna
terminal
terminal
AM dummy
antenna (50
antenna (50
Ω
)
30
Ω
65 pF
15 pF
set
Adjustment Location : tuner unit (TU10)
–set upper view–
AM Auto Scan/Stop Level Adjustment
Setting :
SOURCE
n MODE button : AM
Procedure :
1. Set to the test mode. (See page 18.)
2. Push the SOURCE button.
3. Push the MODE button and set to AM.
1. Set to the test mode. (See page 18.)
2. Push the SOURCE button.
3. Push the MODE button and set to AM.
Display
4. Push the preset 3 button.
Display
5. Adjust with the volume RV1 on TU10 so that the “AM”
indication turns to “AM0” indication on the display window.
But, in case of already indicated “AM0”, turn the RV1 so that
put out light “0” indication and adjustment.
But, in case of already indicated “AM0”, turn the RV1 so that
put out light “0” indication and adjustment.
Display
Carrier frequency : 1000 kHz
30% amplitude
modulation by
1 kHz signal
output level
30% amplitude
modulation by
1 kHz signal
output level
: 33 dB (44.7
µ
V)
Adjustment Location : tuner unit (TU10)
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