Sony ICFM-770-LS Service manual
ICF-M770L/M770S/M770SL
SERVICE MANUAL
Ver 1.1 2002.06
Photo: ICF-M770SL
SPECIFICATIONS
Time display: 24-hour system
Frequency range:
Band ICF-M770L ICF-M770S ICF-M770SL Channel
FM 87.5 – 87.5 – 87.5 – 0.05 MHz
108 MHz 108 MHz 108 MHz
SW — 5 800 – 5 800 – 5 kHz
MW 531 – 531 – — 9 kHz
1 602 kHz 1 602 kHz
LW 153 – — 153 – 9 kHz
279 kHz 279 kHz
Speaker: 12 cm (43⁄4 inches), 8 Ω
Power output: 350 mW (at 10% harmonic
distortion)
Output: v (earphone) jack (ø 3.5 mm minijack)
Power requirements:
220–230 V AC, 50Hz
6 V DC, four R20 (size D) batteries
Dimensions:
Approx. 277 × 156 × 71.5 mm (w/h/d)
(Approx. 11 × 6
parts and controls
Mass: Approx. 1 540 g (3lb 6
Supplied accessories: AC power cord (1)
Design and specifications are subject to change
without notice.
15 900 kHz 15 900 kHz
1
⁄4 × 27⁄8 inches) incl. projecting
) incl. batteries
oz
AEP Model
ICF-M770L/M770SL
UK Model
ICF-M770L
Italian Model
East European Model
ICF-M770S
step
9-873-657-02 Sony Corporation
2002F0500-1 Personal Audio Company
C 2002.06 Published by Sony Engineering Corporation
ICF-M770L
FM/MW/LW PLL SYNTHESIZED
ICF-M770S
FM/SW/MW PLL SYNTHESIZED
ICF-M770SL
FM/SW/LW PLL SYNTHESIZED
ICF-M770L/M770S/M770SL
SECTION 1
SERVICING NOTE
TABLE OF CONTENTS
1. SERVICING NOTE................................................. 2
2. GENERAL .................................................................. 3
3. DISASSEMBLY
3-1. Disassembly Flow ........................................................... 4
3-2. Cabinet Rear Assy........................................................... 4
3-3. Chassis Assy.................................................................... 5
3-4. MAIN Board ................................................................... 5
4. ELECTRICAL ADJUSTMENTS........................ 6
5. DIAGRAMS
5-1. Block Diagram ............................................................... 8
5-2. Note for Printed Wiring Boards and
Schematic Diagrams ....................................................... 9
5-3. Printed Wiring Boards
– MAIN/JACK/POWER/INLET Boards –.................... 10
5-4. Schematic Diagram
– MAIN/JACK/POWER/INLET Boards –.................... 11
5-5. Printed Wiring Board – KEY Board –.......................... 12
5-6. Schematic Diagram – KEY Board – ............................ 13
5-7. IC Pin Function Description .......................................... 14
6. EXPLODED VIEWS
6-1. Cabinet (Front) Section................................................... 15
6-2. Cabinet (Rear) Section .................................................... 16
6-3. Chassis Section ............................................................... 17
HOW TO CHANGED THE CERAMIC FILTERS
This model is used two ceramic filters of CF2 and CF3.
You must use same type of color marked ceramic filters in order to
meet same specifications.
Therefore, the ceramic filter must be changed two pieces together
since it’s supply two pieces in one package as a spare parts.
Mark Center frequency
CF2
mark
CF3
red 10.70 MHz
blue 10.67 MHz
orange 10.73 MHz
black 10.64 MHz
white 10.76 MHz
7. ELECTRICAL PARTS LIST .............................. 18
Notes on chip component replacement
•Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED
LINE WITH MARK 0 ON THE SCHEMATIC DIAGRAMS
AND IN THE PARTS LIST ARE CRITICAL TO SAFE
OPERATION. REPLACE THESE COMPONENTS WITH
SONY PARTS WHOSE PART NUMBERS APPEAR AS
SHOWN IN THIS MANU AL OR IN SUPPLEMENTS PUBLISHED BY SONY.
2
SECTION 2
GENERAL
ICF-M770L/M770S/M770SL
This section is extracted from
instruction manual.
Rear
A
Arrière
Rückseite
Parte posterior
Achterkant
B
To a wall outlet
Vers une prise murale
An eine Netzsteckdose
A la toma de pared
Naar een stopcontact
To AC IN
Vers AC IN
An AC IN
A AC IN
Naar AC IN
R20 (size D) × 4
R20 (D) × 4
R20 (Größe D) × 4
R20 (tamaño D) × 4
R20 (D) × 4
Insert E side of the battery first.
Insérez la borne E de la pile en premier.
Legen Sie die Batterien mit dem Minuspol
E zuerst ein.
Inserte primero el lado E de la pila.
Breng de E kant van de batterij eerst in.
AC power cord
Cordon d’alimentation secteur
Netzkabel
Cable de alimentación de CA
Netsnoer
Setting the Clock
“0:00” will flash in the display when the batteries
are installed or the AC power cord is plugged in
for the first time.
The clock can be adjusted only when the radio is
turned off.
1
Press mb/CLOCK (CLOCK for ICFM770L) for more than 2 seconds.
The “hour” starts flashing.
2
Turn TUNE/TIME SET to set the hour for
the current time, then press mb/CLOCK
(CLOCK for ICF-M770L).
The “minute” starts flashing.
3
Turn TUNE/TIME SET to set the minute
for the current time, then press mb/
CLOCK (CLOCK for ICF-M770L).
The clock starts operating, and “:” starts flashing.
To set the current time exactly to the second, adjust
the minute and then press mb/CLOCK (CLOCK for
ICF-M770L) to synchronize with a time signal (such
as the telephone time signal).
How to Adjust the Time Digits
When you turn TUNE/TIME SET to or , the
time digits move forward or backward by one step,
and when you turn it to
move rapidly.
Notes
• If you do not operate mb/CLOCK (CLOCK for ICF-
M770L) or TUNE/TIME SET within 65 seconds,
the clock setting mode will be cancelled.
•24-hour system : “0:00” = midnight, “12:00” = noon
Using the Backlight Function
Press LIGHT to turn on the backlight.
To turn off the backlight, press LIGHT again.
When operating the unit on batteries
The backlight will turn off automatically after 30
seconds to save the batteries. However, if you
operate the radio while the backlight is lit, it will
stay on for another 30 seconds.
To turn off the backlight before the time has
elapsed, press LIGHT.
or , the time digits
HOLD OPERATION
LIGHT
STANDBY
mb/CLOCK TIME SET ON/OFF SLEEP
CLOCK for ICF-M770L
CLOCK pour ICF-M770L
CLOCK beim ICF-M770L
CLOCK para ICF-M770L
CLOCK voor ICF-M770L
v jack
Prise v
Buchse v
Toma v
v aansluiting
C
FM SW MW/LW
SCAN
TONE
TUNE/
TIME
SET
VOL
*The PRESET TUNING 4 button has a
tactile dot.
* La touche PRESET TUNING 4 a un point
tactile.
*Auf der PRESET TUNING-Taste 4
befindet sich ein fühlbarer Punkt.
*La tecla PRESET TUNING 4 tiene un
punto táctil.
*De PRESET TUNING 4 toets is voorzien
van een voelstip.
PRESET TUNING
STATION SELECT/ PRESET
BAND
1234567
*
Telescopic Antenna
Antenne télescopique
Teleskopantenne
Antena telescópica
Telescoopantenne
TUNE/TIME SET
VOL
TONE
3
ICF-M770L/M770S/M770SL
)
• This set can be disassembled in the order shown below.
3-1. DISASSEMBLY FLOW
SET
3-2. CABINET (REAR) ASSY
(page 4)
3-3. CHASSIS ASSY
(page 5)
3-4. MAIN BOARD
(page 5)
SECTION 3
DISASSEMBLY
Note: Follow the disassembly procedure in the numerical order given.
3-2. CABINET (REAR) ASSY
main board
5
Remove five solders.
4
3
telescopic antenna (ANT1)
2
screw (P3 × 10)
6
1
six screws
(BTP3
cabinet (rear) assy
×
14
main board
4
3-3. CHASSIS ASSY
)
ICF-M770L/M770S/M770SL
4
chassis assy
1
knob (jog)
3-4. MAIN BOARD
3
key board
4
3
knob (control) (tone)
claw
2
knob (control) (vol
5
main board
1
two screws
(P2
4
three claws
×
8)
2
claw
5
ICF-M770L/M770S/M770SL
SECTION 4
ELECTRICAL ADJUSTMENTS
0 dB=1 µV
[MW/LW]
Setting:
BAND switch: MW or LW
AM RF signal
generator
30% amplitude
modulation by
400 Hz signal
Output level: as low as possible
[FM]
Setting:
BAND switch: FM
FM RF signal
generator
22.5 kHz frequency
deviation by 400 Hz
signal
Output level: as low as possible
[SW] (ICF-M770S/M770SL)
Setting:
BAND switch: SW
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.
MAIN board
0.01 µF
11 pF
TP (ANT)
MAIN board
TP (ANT)
set
set
set
level meter
32 Ω
JACK board
v jack (J201)
level meter
32 Ω
JACK board
v jack (J201)
level meter
32 Ω
JACK board
v jack (J201)
no mark: common
(): ICF-M770L
[]: ICF-M770S
〈〈 〉〉 : ICF-M770SL
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter
T1 450 kHz
MW VT VOLTAGE ADJUSTMENT
+
–
+
–
+
–
Adjustment Part Frequency Display Reading on Dig ital Voltmeter
(L8) [L10] 531 kHz 2.5 ± 0.1 V [2.8 ± 0.1 V]
Confirmation 1,602 kHz 9.6 ± 1.0 V
MW TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
(L5-1) [L5] 603 kHz
(CT1) [CT2] 1,404 kHz
LW VT VOLTA GE ADJUSTMENT
Adjustment Part Frequency Display Reading on Dig ital Voltmeter
(CT3) 〈〈L10〉〉 153 kHz 2.2 ± 0.1 V 〈〈2.8 ± 0.1 V〉〉
Confirmation 279 kHz 8.6 ± 1.0 V
LW TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
(L5-2) 〈〈L5〉〉 162 kHz
CT2 243 kHz
FM VT VOLTAGE ADJUSTMENT
Adjustment Part Frequency Display Reading on Dig ital Voltmeter
L14 87.5 MHz 2.9 ± 1.0 V
Confirmation 108 MHz 9.1 ± 1.0 V
FM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L12, 13 87.5 MHz
CT4 108 MHz
digital voltmeter
MAIN board
TP (VT)
100 kΩ
+
–
•Repeat the procedures in each adjustment several times, and the
tracking adjustments should be finally done by the trimmer capacitors.
• Remove FM/SW antenna in FM/SW adjustment.
6
SW VT VOLTAGE ADJUSTMENT*
Adjustment Part Frequency Display Reading on Dig ital Voltmeter
L8 5,800 kHz 2.7 ± 0.1 V
Confirmation 15,900 kHz 9.1 ± 1.0 V
SW TRACKING ADJUSTMENT*
Adjust for a maximum reading on level meter
L3 5,800 kHz
CT1 15,900 kHz
*: ICF-M770S/M770SL
Adjustment Location: MAIN board (See page 7)
Adjustment Location:
– MAIN BOARD (Component Side) –
MW VT Voltage Adjustment (M770S)
L10
LW VT Voltage Adjustment (M770SL)
CT3
LW VT V oltage
Adjustment (M770L)
CT1
SW Tracking Adjustment (M770S/M770SL)
L3
MW VT Voltage Adjustment (M770L)
L8
SW VT Voltage Adjustment (M770S/M770SL)
L14
FM VT Voltage
Adjustment
ICF-M770L/M770S/M770SL
CT2 MW Tracking Adjustment (M770S)
L5 LW Tracking Adjustment (M770SL)
– MAIN BOARD (Conductor Side) –
TP
(VT)
T1
AM IF
Adjustment
L13
L12 FM T racking Adjustment
CT4
CT1
MW Tracking Adjustment (M770L)
L5-1
TP
(ANT)
CT2
LW Tracking Adjustment (M770L)
L5-2
77
ICF-M770L/M770S/M770SL
5-1. BLOCK DIAGRAM
ANT1
FM/SW
ANTENNA
SECTION 5
DIAGRAMS
CT4, L12, 13
FM TRACKING
(M770L)
FERRITE-ROD
FERRITE-ROD
M770S/
M770SL
(M770L)
(M770S)
FERRITE-ROD
CT1, L5-1
MW TRACKING
CT2, L5
MW TRACKING
FM/(SW/MW/LW) BAND
SELECT SWITCH
25 24
M770S/
M770SL
L5-1
MW
ANTENNA
L5-2
LW
ANTENNA
L5
MW/LW
ANTENNA
Q5
3
XIN
X101
75kHz
L3
SW
RF
CT1, L3
LW TRACKING
(M770L)
CT2, L5-2
LW TRACKING
(M770SL)
LW TRACKING
BPF
XOUT
REG
+1.2V
REG
+1.2V
CT2, L5
SW
SWITCH
Q1
Q2
SW
SWITCH
VCC B+
Q6
REG
+1.2V
VCC B+
M770S/
M770SL
MW/LW
SWITCH
D2-1
CT2
SW BAND
SELECT SWITCH
Q3
M770S/
M770SL
4
LCD0 – LCD1221COM0 – COM3
35 – 47
LIQUID CRYSTAL DISPLAY
LCD101
B.P.F.
BPF1
CT1
(MW/LW)/SW
31 – 34
D1-1
L12, 13
FM RF
(M770L)
LOW-PASS FILTER
Q104, 110
19
EO
D6
(M770L)
CT4
FM
RF IN
13
AM
RF IN
11
(M770L)
L8
SW/MW
OSC
CT3
CT3
LW VT
VOLTAGE
IC104
MW/LW
SWITCH
D2-2
SWITCH
Q7
MW/LW
SWITCH
Q4
L10
MW/LW
OSC
SYSTEM CONTROLLER,
LIQUID CRYSTAL DISPLAY DRIVER,
KEY CONTROL
KS0 – KS4
1, 6 – 9
KEY MATRIX
S101 – 119
10
FM
RF
FM
FRONT-END
AM
FRONT-END
AM OSC
6 8
M770S/
M770SL
D1-2
SW
Q4
M770S/
M770SL
M770S/
M770SL
KR0 – KR3
10 – 13
• SIGNAL PATH
FM/AM FRONT-END,
FM/AM IF AMP, DET, AGC, AF AMP
CF3
T1
AM IF
D7
L10
MW VT
CF2
10.7MHz
T1
AM IFT
L14
L14
FM OSC
(M770L)
L8
MW VT
VOLTAGE
FM/(SW/MW/LW) BAND
SELECT SWITCH
(M770SL)
VOLTAGE
+3V B+
HOLD
10.7MHz
450kHz
L10
LW VT
S120
HOLD
OFF
10.7MHz
CF1
(M770S/M770SL)
Q108
CF4
3
17
FM/(SW/MW/LW) BAND
SELECT SWITCH
L8
SW VT
VOLTAGE
(LCD BACK LIGHT)
FM
IF IN
FM
DISCRI
DISCRIMINATOR
AM
IF IN
AM IF AMP,
AGC, DET
FM/AM
BAND
SELECT
LED DRIVE
D104, 105
TUNING METER
16 4 5
Q10
56
AM/(FM/TV)
LIGHT
16
Q107
FM/AM
IF OUT
15 18
+
FM OSC
FM VT VOLTAGE
FM VCO
BUFFER
Q8
(M770S)
VOLTAGE
FM VCO
BUFFER
Q105
20
VCOL
VCOH
HOLD
17
FM
IF AMP
FM
20
METER
IC1
DET
OUT
24
+
RV2
TONE
Q11, 12
TONE
CONTROL
SWITCH
REG OUT
9
REG +1.2V
D9
14
52
BEEP
TUNED
2
MUTE
AC DET
VDET1
CEDET
VDET2
POWER
15
50
51
53
5
LOW-PASS
FILTER
CIRCUIT
B+
AC DETECT
VOLTAGE DETECT
VOLTAGE DETECT
Q106, 111, T101
D102
POWER ON/OFF
CONTROL SWITCH
Q103
BATTERY
IC102
BATTERY
IC103
VCC B+
DC/DC
CONVERTER
Q102
AF
IN
25
AC DETECT
Q201
B+ SWITCH
Q101
B+ SWITCH
Q109
AF
POWER AMP
NF
VOL
+3V B+
MUTING
SWITCH
Q9
RECT
D205, 206
AF
OUT
28
+3V
REGULATOR
IC101
RV1
VOL
D201
: FM
: MW/LW
T202
POWER
TRANSFORMER
D202 – 204
J201
v
SP1
J301
AC IN -
DRY BATTERY
SIZE "D"
(IEC DESIGNATION R20)
4PCS. 6V
88
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