Sony WX-C770 Service Manual ▷ View online
– 33 –
antenna
terminal
terminal
AM RF signal
generator
AM dummy
antenna (50
antenna (50
Ω
)
set
30
Ω
15 pF
65 pF
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)
Procedure :
1. Set to the test mode. (See page 32.)
2. Push twice the TUNER button and set to AM.
1. Set to the test mode. (See page 32.)
2. Push twice the TUNER button and set to AM.
Display
3. Push the preset 3 button.
Display
4. Adjust with the volume RV1 on TU1 to the position at which
the characters “AM” start to scroll from the right on the display
window.
window.
Display
AM Auto Scan/Stop Level Adjustment
Note : This adjustment should be performed after the FM Auto
Scan / Stop Level Adjustment is done.
Setting :
TUNER button (twice)
: AM
FREQUENCY SELECT switch : AM 10 K
FM Stereo Separation Adjustment
Setting :
TUNER button
: FM
FREQUENCY SELECT switch : FM 200 K
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 :1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot : 7.5 kHz deviation (10%)
sub :1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot : 7.5 kHz deviation (10%)
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 34.
FM stereo
Level meter
Level meter
signal generator
connection
reading (dB)
output channel
L-CH
L-CH
A
B
B
R-CH
L-CH
Adjust RV4 on TU1 for
minimum reading.
R-CH
R-CH
C
D
D
L-CH
R-CH
Adjust RV4 on TU1 for
minimum reading.
Procedure :
antenna
terminal
terminal
LINE OUT REAR
FM RF signal
generator
0.01
µ
F
10 k
Ω
level meter
set
SHUF1
PRESET
SHUF1
PRESET
SHUF1
Adjustment Location : See page 34.
– 34 –
Adjustment Location :
– set upper view –
– set lower view –
TAPE SPEED ADJ
TU1
RV1 AM AUTO SCAN/STOP LEVEL ADJ
RV2 FM AUTO SCAN/STOP LEVEL ADJ
RV4 FM STEREO SEPARATION ADJ
RV200
(R-CH)
(R-CH)
RV100
(L-CH)
(L-CH)
DOLBY LEVEL ADJ
R-CH
L-CH
L-CH
TP (DOLBY)
DOLBY LEVEL ADJ
DOLBY LEVEL ADJ
– 35 –
RF signal waveform
VOLT / DIV : 200 mV
TIME / DIV : 500 nS
TIME / DIV : 500 nS
level : 1.0 – 1.5 Vp-p
servo board
TP (RF)
TP (RF GND)
oscilloscope
CD SECTION
Note :
1. CD Block basically constructed to operate without adjustment.
1. CD Block basically constructed to operate without adjustment.
Therefore, check each item in order given.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use the oscilloscope with more than 10 M
3. Use the oscilloscope with more than 10 M
Ω
impedance.
4. Clean an objective lens by an applicator with neutral detergent
when the signal level is low than specified value with the
following checks.
following checks.
Focus Bias Adjustment
Setting : This adjustment is performed with the set placed
horizontally.
Focus Gain Adjustment (Coarse adjustment)
This adjustment is not required unless the following parts are
replaced:
•
replaced:
•
Optical pick-up
•
RV4
Procedure :
1. Set RV4 to the standard position. (mechanical center)
2. Check whether operation noise (while noise type) caused by
1. Set RV4 to the standard position. (mechanical center)
2. Check whether operation noise (while noise type) caused by
the 2-axis device (lens section of the optical pick-up) is abnormally
loud.
If the operation noise is too loud, turn RV4 slightly counter-
clockwise.
loud.
If the operation noise is too loud, turn RV4 slightly counter-
clockwise.
•
If the gain is too low :
Focus does not function and no music is selected.
Focus does not function and no music is selected.
•
If the gain is too high :
Noise caused by scratches and dust is heard and the operation
becomes unstable.
Noise caused by scratches and dust is heard and the operation
becomes unstable.
Adjustment Location : servo board
Adjustment Location : servo board (component side)
Procedure :
1. Connect an oscilloscope between TP (RF) and TP (RF GND)
1. Connect an oscilloscope between TP (RF) and TP (RF GND)
on the servo board.
2. Connect the power supply.
3. Push the RESET button (SW701) on the control board.
4. Insert the disc (YEDS-18) and playback.
5. Adjust RV1 so that the oscilloscope waveform is clear and check
3. Push the RESET button (SW701) on the control board.
4. Insert the disc (YEDS-18) and playback.
5. Adjust RV1 so that the oscilloscope waveform is clear and check
RF signal level is correct or not.
Note : Clear RF signal waveform means that the sharp “
≈
” can be
clearly distinguished at the center of the waveform.
• When observing the eye pattern, set the oscilloscope to AC range
and raise the vertical sensitivity so that it may be easily seen.
Adjustment Location : servo board
FOCUS GAIN ADJ
RV4
RV1
FOCUS BIAS ADJ
IC3
CN2
CN1
IC1
TP
(RF)
CN3
IC2
TP
(RF GND)
– 37 –
6-1. IC PIN DESCRIPTIONS
• IC301
• IC301
µ
PD78058GC-F48-3B9 (SYSTEM CONTROL)
Pin No.
Pin Name
I/O
Pin Description
1
VSM
I
FM/AM common signal meter A/D conversion input
2
NIL
I
Not used. (Connect to GND.)
3
SD-IN
I
Station detector detection input
4
AVSS
–
GND for A/D conversion.
5
FM-ST
I/O
Used in conjunction with stereo input/monaural output. (FM mode)
6
AM-ST
I
AM stereo input
7
AVREF
–
Reference voltage power supply for D/A conversion.
8
PLL-SI
I
PLL serial data input
9
PLL-SO
O
PLL serial data output
10
PLL-CKO
O
PLL serial clock output
11
PLL-CE
O
PLL serial chip enable output
12
AMS
I
Music with/without detection input at AMS.
13
PLAY/AMS
O
TAPE AMS control output
14
F/R
O
FWD/REV detection output
15
MTL
O
METAL control output
16
BUS-SI
I
Serial data input (for SONY BUS)
17
BUS-SO
O
Serial data output (for SONY BUS)
18
BUS-CKI
I
Serial clock input (for SONY BUS)
19
BUS-CKO
O
Serial clock output (for SONY BUS)
20
TAPE-MUTE
O
Tape mute control output
21
DOLON
I/O
DOLBY control input/output
22
EQ-CE
O
Equalizer control output
23
EQ-CLK
O
Equalizer control output
24
DATA
O
Serial data output
25
VOL-CLK
O
Electronic volume serial clock output
26
VOL-CE
O
Electronic volume serial chip enable output
27
MUT
O
System mute control output
28
AMP-ON
O
Power amplifier power control output
29
AUX-MUT
O
Not used.
30
C/B
I/O
DOLBY B/C select control input/output (Not used.)
31
PWR-SEL
I
Power select initial setting
32
TEST
I
Test mode setting input
33
VSS
–
Microcomputer GND
34
NIL
I
Not used. (Connect to GND.)
35
POWER-ON
O
System power control output
36
TUN-ON
O
Tuner power control output
37
FM-ON
O
FM power control output
38
AM-ON
O
AM power control output
39
NIL
I
Not used. (Connect to GND.)
40
CM-ON
O
Capstan motor control output
41
TP-ON
O
Tape power control output
42
LM-EJ
O
Loading motor control output (Eject direction)
43
LM-LOD
O
Loading motor control output (Loading direction)
44, 45
POS1, 0
I
Position signal detection input
46
BEEP
O
Buzzer control output
47, 48
POS2, 3
I
Position signal detection input
49
REL
I
Reel table rotation detection input
50
RC-IN1
I
Rotary commander input
51
SUB-CE
O
Sub volume serial chip enable output
52
SUB-DATA
O
Sub volume serial data output
53
SUB-CLK
O
Sub volume serial clock output
SECTION 6
DIAGRAMS
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