Sony SRF-M73 Operating Instructions (primary... User manual

MICROFILM
SERVICE MANUAL
FM STEREO/AM PLL SYNTHESIZED RADIO
US Model
Panama Model
SPECIFICATIONS
SRF-M73
Ver 1.0 1999. 03

– 2 –
TABLE OF CONTENTS
1. SERVICING NOTES............................................... 2
2. GENERAL ................................................................... 3
3. DISASSEMBLY ......................................................... 4
4. ELECTRICAL ADJUSTMENTS......................... 6
5. DIAGRAMS
5-1. Block Diagram ................................................................ 8
5-2. Printed Wiring Boards..................................................... 10
5-3. Schematic Diagram ......................................................... 13
5-4. IC Pin Function Description ........................................... 18
6. EXPLODED VIEWS................................................ 19
7. ELECTRICAL PARTS LIST ............................... 20
Forced Reset
The system microprocessor can be reset in the following proce-
dure.
Use these procedure when the unit cannot be worked normally
due to the overrunning of the microprocessor, etc.
Procedure:
1. Set to radio OFF.
2. While pressing the [SCAN] button, press two buttons of [START/
STOP] and [BAND] simultaneously for 5 seconds.
3. The unit is reset, and display blinking “AM 12:00”.
SECTION 1
SERVICING NOTES

– 3 –
SECTION 2
GENERAL This section is extracted from
instruction manual.

– 4 –
CABINET (FRONT)/(REAR) ASSY
KEY BOARD
·This set can be disassembled in the order shown below.
SECTION 3
DISASSEMBLY
Set
Key Board Main Board Knob (A
)
Cabinet (Rear) Assy
Cabinet (Front) Assy
2 three screws
(B1.7 × 8)
2 two screws
(B1.7 × 8)
1 Remove the battery case lid
of the arrow.
3 cabinet (front) assy
4 cabinet (rear) assy
1 three claws
2 Open the key board
to direction of the arrow.
1 four claws
Note: Follow the disassembly procedure in the numerical order given.

– 5 –
MAIN BOARD
KNOB (A)
Note: Check that two switch (S1,
S2) is latched with two
adaptors when carrying
out installation.
2 screw
(B1.7
× 8)
1 Remove two solders.
3 knob (vol)
4 two claws
S1
S2
5 main board
2 two knobs (A)
1 claw
1 claw
3 two adaptors

– 6 –
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter
T1 450 kHz
AM VCO VOLTAGE ADJUSTMENT
Adjustment Part Frequency Display Reading on Digital Voltmeter
L4 530 kHz (531 kHz) 3 ± 0.1V
Confirmation 1710 kHz (1602 kHz) 9 ± 1V (8.5 ± 1V)
AM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L1 580 kHz (621 kHz)
CT1 1,490 kHz (1,395 kHz)
FM VCO VOLTAGE CONFIRMATION
Frequency Display Reading on Digital Voltmeter
87.5 MHz 3 ± 0.3V
108 MHz Less than 11 ± 1V
FM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L2 87.5 MHz
CT2 108 MHz
( ): Panama model
SECTION 4
ELECTRICAL ADJUSTMENTS
0 dB = 1 µV
[AM]
Setting:
Band switch: AM
[FM]
Setting:
Band switch: FM
• Repeat the procedures in each adjustment several times, and the
tracking adjustments should be finally done by the trimmer ca-
pacitors.
Adjustment Location: Main Board (See page 7)
FM RF signal
generator
22.5 kHz frequency
deviation by 400 Hz
signal
Output level: as low as possible
+
–
level meter
2 jack (J1)
set
MAIN board
TP (FM IN) 32
Ω
0.01 µ F
+
–
digital voltmete
r
MAIN board
TP (VT)
FM Free-Run Adjustment
Setting:
Procedure:
1. Connect the frequency counter toTP (MPX) as shown the fig-
ure below.
2. Tune the set to 98 MHz.
3. Adjust RT1 for 76 kHz reading on the frequency counter.
Specification: 75.8 kHz to 76.2 kHz
Adjustment Location: MAIN board (See page 7)
0.01 µ F
MAIN boar
d
TP (FM IN)
set
FM RF signal
generator
Carrier frequency : 98 MHz
Modulation : no modultion
Output level : 0.1 V
(
100 dB
)
+
–
MAIN board
TP (MPX)
+
1 µ F
frequency
counter
AM RF signal
generator
30% amplitude
modulation by
400 Hz signal
Output level: as low as possible
Put the lead-wire
antenna close to
the set.
+
–
level meter
set
32 Ω
2
jack (J1)

SRF-M73
– 7 – – 8 – – 9 –
– MAIN BOARD (Component Side) –
Adjustment Location:
– MAIN BOARD (Conductor Side) –
L4
AM VCO Voltage Adjustment
RT1
FM Free-Run Adjustment
CT1
AM Tracking Adjustment
L1
AM Tracking Adjustment
T1
AM IF Adjustment
FM Tracking Adjustment
CT2
L2
TP
(MPX)
TP
(FM IN)
TP
(VT)



J1
SECTION 5
DIAGRAMS
5-1. BLOCK DIAGRAM
18
20
16 13
19
24 22
FM
FRONT-END FM IF AMP/
DISCRI DECODER
AMP
SWITCH
BASS
BOOST
CONTROL
POWER
AMP
DET
REGULATOR
1/2
COUNTER
1/2
COUNTER
AM IF AMP/
DET
TUNING
INDICATOR
PD1
VCO
PD2
AM
FRONT-END
14
FM RF
IN FM/AM
MIX OUT
CF3: US
CF4, 5: PANAMA
10.7MHz
CF1
10.7MHz
BASS BOOST AMP
IC2
SYSTEM CONTROLLER,
LIQUID CRYSTAL DISPLAY DRIVER,
KEY CONTROL
IC101
EEPROM
IC105
CF2
450kHz
FM
RF
26
FM DISCRI
FM
IF IN 6
721
5
1
2
14
13
L-CH
OUT
R-CH
OUT
4
27
29
123
ST IND
AM
IF IN
PILOT DET LPF2
12
TUNE IND
9
AFC1/AGC
15
BAND
SELECT
PILOT DET LPF1 PLL LPF1
PLL LPF2
VCO AM OSC FM OSC
AM RF
IN
FM/AM FRONT-END,
FM/AM DET, MPX
IC1
RT1
FM FREE-RUN
L4
AM VCO VOLTAGE
CT2, L2
FM TRACKING
S1
FM SENS
T1
AM IF
CT1, L1
AM TRACKING
L.P.F.
B.P.F.
BPF1
FM VCO
BUFFER
Q1
FM/AM BAND
SELECT SWITCH
Q3
COMPARATOR
IC4 (1/2)
LIQUID CRYSTAL DISPLAY
LCD101
VOLTAGE
DETECT
IC102
B+ SWITCH
Q104
DC/DC
CONVERTER
Q103, T101
B+ SWITCH
Q6
AM IF
BUFFER
Q4, 5
LOW-PASS
FILTER
Q101
• SIGNAL PATH
: FM
: AM
05
POWER
AMP
MUTE
CONTROL
RIPPLE FILTER
Q2
KEY MATRIX
S101 – 111, 113 – 116
KS0 – KS3 KR0 – KR3
X101
75kHz
SYSTEM CONTROLLER (IC101),
EEPROM (IC105) B+
FM/AM TUNER (IC1),
HEADPHONE AMP (IC3) B+
BASS BOOST AMP (IC2) B+
PLL LOW-PASS FILTER CIRCUIT B+
AM IF AMP CIRCUIT B+
D105
–1
–2
IN1
IN2
HEADPHONE AMP
IC3
2
4
IN1
IN2
OUT1
OUT2
9
7
OUT1
OUT2
LP
GAIN
B+
VREF
5
67
COMPARATOR
IC4 (2/2)
3
21
B+
CT1
D1-1
L1
AM FERRITE-ROD
ANTENNA
L2
FM RF
(PANAMA)
POWER XOUT XIN
IF ON
CE
DET IN
MT/SW
REG
VCC
AM IF IN
EO
VCOL
VCOH
BAND
CMP IN
24
DATA
15
CK
14
2 1
CS
SK
3
DI
4
DO
CS
16 25 2 1 50
6
12
10
53
MUTE
5
BEEP
52
3
17212019
DX
LOCAL
S2
MEGA
BASS
ON
OFF
D1-2 D3
CT2
D2
L4
AM OSC L3
FM OSC
RV1
VOL
J1
(HEADPHONE)
2
+
DRY BATTERY
SIZE “AAA”
(IEC DESIGNATION R03)
2PCS. 3V
10 – 136 – 9
COM0 – COM3
31 – 34
SEG0 – SEG14
35 – 49

SRF-M73
– 13 – – 14 – – 15 – – 16 –
• Waveforms
– KEY Board –
1IC101 @¢ XOUT
200 mV/DIV, 10 µs/DIV
5-3. SCHEMATIC DIAGRAM • See page 17 for IC Block Diagrams.
2Q103 Base-1, Collector-2
(RADIO ON mode)
200 mV/DIV, 100 ns/DIV
3Q103 Collector-1 (RADIO ON mode)
2 V/DIV, 100 ns/DIV
208 m Vp-p
13.3
µ s
616 m Vp-p
243 ns
4.9 Vp-p
243 ns
Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
• All resistors are in Ωand 1/4W or less unless otherwise
specified.
•¢: internal component.
•C: panel designation.
•U: B+ Line.
•H: adjustment for repair.
• Power voltage is dc 3 V and fed with regulated dc power
supply from battery terminal.
• Voltages and waveforms are dc with respect to ground
under no-signal (detuned) conditions.
no mark : FM
():AM
• Voltagesaretakenwith aVOM(Inputimpedance 10 MΩ).
Voltage variations may be noted due to normal produc-
tion tolerances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal produc-
tion tolerances.
• Circled numbers refer to waveforms.
• Signal path.
F: FM
f: AM
FM FREE-RUN