Sony ICF-C273 - Fm/am Clock Radio User manual

ICF-C273
SERVICE MANUAL
FM/AM PLL SYNTHESIZED CLOCK RADIO
SPECIFICATIONS
Australian Model
Ver 1.0 2004.03
9-877-642-01
2004C02-1
© 2004.03
Sony Corporation
Personal Audio Company
Published by Sony Engineering Corporation
Time display
12 hour
Frequency range
Band Channel step
FM 87.5-108 MHz 0.05 MHz
AM 531-1 602 kHz 9 kHz
Speaker Approx. 6.6 cm (2 5/8in.) dia. 8 Ω
Power output
200 mW (at 10% harmonic distortion)
Power requirements
230 VAC, 50 Hz
Dimensions
Approx. 173 x 57.2 x 133.5 mm (w/h/d)
(6 7/8x 2 3/8x 5 3/8in.) incl. projecting parts and controls
Mass Approx. 630 g (1 lb 6.2 oz)
Design and specifications are subject to change without notice.

ICF-C273
2
TABLE OF CONTENTS
Specifications ........................................................................... 1
1. GENERAL
Location and Function of Controls .................................... 3
2. DISASSEMBLY
2-1. Switch Board, Cabinet (Upper) .................................. 6
2-2. Alarm Board, jog Board.............................................. 7
2-3. Main Board ................................................................. 7
2-4. Trans Board ................................................................ 8
3. ELECTRICAL ADJUSTMENTS............................. 9
4. DIAGRAMS
4-1.IC Block Diagrams .....................................................11
4-2.Block Diagrams ......................................................... 12
4-3. Printed Wiring Board –Main section (1/2)– ............. 13
4-4. Printed Wiring Board –Main section (2/2)– ............. 14
4-5. Schematic Diagram –Main section (1/2)– ................ 15
4-6. Schematic Diagram –Main section (2/2)– ................ 16
5. EXPLODEDVIEW
5-1.Cabinet (Upper) Section ............................................ 17
5-2.Cabinet (Lower) section ............................................ 18
6. ELECTRICAL PARTS LIST................................... 19
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK 0OR DOTTED LINEWITH
MARK 0ON THE SCHEMATIC DIAGRAMS AND IN THE PARTS
LIST ARE CRITICALTO SAFE OPERATION.
REPLACE THESE COMPONENTS WITH SONY PARTS WHOSE
PART NUMBERS APPEAR AS SHOWN IN THIS MANUAL OR IN
SUPPLEMENTS PUBLISHED BY SONY.
• HOWTO CHANGETHE CERAMIC FILTER
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 change two pieces together
since it's supply two pieces in package as a spare parts.
mark mark
CF3
CF2
no mark
blue
orange
black
white
10.70MHz
10.67MHz
10.73MHz
10.64MHz
10.76MHz
Mark Center
frequency

ICF-C273
3
SECTION 1
GENERAL
LOCATION AND FUNCTION OF CONTROLS
This section is extracted from
instruction manual.
AC power cord
VOLUME
There is a tactile dot beside volume
to show the direction to turn up the
volume.
Jog lever
FM wire antenna
The PRESET TUNING 3 button has
a tactile dot.

ICF-C273
4
Setting the Clock and Date
1Plug in the clock radio.
The display will flash “AM12:00” or “0:00”.
2Press CLOCK for a few seconds.
You will hear a beep and the year will start to flash in the display.
3Press Jog lever v(up) or V(down) until the correct year appears in the
display.
4Press ENTER/BRIGHTNESS.
5Repeat steps 3 and 4 to set the month, day, hour, and minute.
After setting the minute, press ENTER/ BRIGHTNESS to start the
counting of the seconds, and you will hear two short beeps.
•To set the current time rapidly, hold down Jog lever v(up) or V
(down).
•The clock system varies depending on the model you own.
12-hour system: “AM 12:00” = midnight
24-hour system: “0:00” = midnight
•In step 5, when you press ENTER/BRIGHTNESS after the minute
setting to activate the clock, the seconds start counting from zero.
•When the alarm setting mode is entered, the clock cannot be set.
To display the year and date
Press SNOOZE/DATE/SLEEP OFF once for the date, and within 2
seconds press it again for the year.
The display shows the date or year for a few seconds and then changes
back to the current time.
To change the display to the daylight saving time
(summer time) indication
Press D.S.T./SUMMER T.
“ ” is displayed and the time indication changes to summer time.
To deactivate the summer time function, press D.S.T./SUMMER T.
again.
To set the brightness of the backlight
If you cannot see the display clearly, press and hold ENTER/
BRIGHTNESS to set the desired brightness (high, middle or low).
Changing AM (MW) Channel Step
The AM (MW) channel step differs depending on area. The channel step
of this unit is factory-set to 9 kHz or 10 kHz to change the setting as
shown below to be able to listen to the radio.
Channel step
9 kHz
1Plug in the clock radio.
Press OFF/ALARM RESET to turn off the power.
2While holding down OFF/ALARM RESET, keep pressing ON/BAND
for more than 5 seconds.
The AM (MW) channel step will be changed.
If you proceed to step 2 again, the channel step changes again.
Notes
•When the AM (MW) channel step is changed, the preset stations for
AM (MW) will be initialized.
• When the AM (MW) channel step is changed, the FM channel step also
will be changed.
Operating the Radio
—ManualTuning
1Press ON/BAND to turn on the radio.
The display shows the band and frequency for a few seconds and then
changes back to the current time.
2Press ON/BAND repeatedly to select the desired band.
Each press changes the band as follows:
tAM tFM1tFM2
When using FM1 or FM2 preset mode, you may listen to the radio on
either mode. (See “Presetting Your Favourite Station”.)
3 Use TUNING + or – to tune into the desired station.
The FM channel step is set to 0.05 MHz* and the AM (MW)
channel step is set to 9 kHz.
*The FM frequency display is raised or lowered by a step of 0.1 MHz.
For example, frequency 88.00 and 88.05 MHz is displayed as “88.0
MHz.”
Two short beeps sound when the minimum frequency of each band is
received during tuning.
4Adjust volume using VOLUME.
•To turn off the radio, press OFF/ALARM RESET.
•To listen with an earphone, connect the earphone to the v(earphone)
jack. The speaker is deactivated when an earphone is connected.
•To check the station being received, press TUNING + or – or ON/
BAND lightly. The display shows the band and frequency for a few
seconds and then changes back to the current time.
Improving the Reception
FM:Extend the FM wire antenna fully to increase
reception sensitivity.
AM (MW):Rotate the unit horizontally for optimum
reception. A ferrite bar is built in to the unit.
Do not operate the unit over a steel desk or metal surface, as this may lead
to interference of reception.
PresettingYour Favourite Station
—PresetTuning
You can preset up to 10 stations in FM (5 stations in FM1, 5 stations in
FM2), and 5 stations in AM.
Presetting a Station
1Follow steps 1 to 4 in “Operating the Radio” and manually tune into the
station you wish to preset.
2Hold down the desired STATION•SELECT/PRESET button
until you hear two short beeps.
Example: To preset AM 1 260 kHz onto preset 2 button.
The display shows the frequency for a few seconds and then changes
back to the current time.
To preset another station, repeat these steps.
To change the preset station, tune into the desired station and hold
down the PRESET TUNING 1 to 5 button. The new station will
replace the previous station on the preset button.
Tuning into a preset station
1Press ON/BAND to turn on the radio.
2Press STATION•SELECT/PRESET
where the desired station is stored.
3Adjust volume using VOLUME.
After a few seconds, the display will return to the current time but the
preset button number will remain.
Setting the Alarm
You can choose from two types of alarm, Radio or Buzzer.
The alarm will come on at the same time everyday.
The factory setting alarm time for the radio and buzzer is 12:00am or
0:00.
Notes
• Set the current time before setting the alarm.
•Radio reception is interrupted while the alarm time is being set.
To set the AlarmTime
1Press and hold ALARMA or ALARM B for a few seconds.
After one beep, the hour flashes in the alarm display.
2Press Jog lever v(up) or V(down) to select the hour.
To set the hour rapidly, hold down Jog lever v(up) or V(down).
3Press ENTER/BRIGHTNESS.
After one beep, the minutes flash on the alarm display.

ICF-C273
5
4Repeat steps 2 and 3 to set the minute.
A beep sounds to confirm the time setting.
“RADIO•SOUND” appears.
You can choose between “RADIO” and “SOUND” modes.
Set the alarm mode as follows:
• RADIO: see “ASetting the RadioAlarm”
• SOUND: see “BSetting the Sound Alarm”
ASetting the Radio Alarm
For the radio alarm, the station you specified as the wake-up station is
played.
1Perform steps 1 to 4 in “To set the Alarm Time.”
2Press Jog lever v(up) or V(down) to select “RADIO” alarm mode.
“WAKE UP STATION” appears in the display.
3Press ENTER/BRIGHTNESS.
After one beep, the preset number flashes in the display.
4Press Jog lever v(up) or V(down) to select the desired wake-up
station.
Preset number changes in the order as follows:
tP– y AM P1 to 5 T
tFM2 P1 to 5 y FM1 P1 to 5 T
“P-” is the last received station.
You can directly select the desired wake-up station by pressing ON/
BAND or the STATION•SELCET/PRESET button while the
indication “P-” is not displayed.
5Press ENTER/BRIGHTNESS.
Two short beeps will confirm the setting, and theALARM A or B
display will disappear.
BSetting the Sound Alarm
For the sound alarm, the sound you specified as the wake-up sound is
played.
1Perform steps 1 to 4 in “To set the Alarm Time.”
2Press Jog lever v (up) or V (down) to select “SOUND” alarm mode.
“WAKE UP SOUND” appears in the display.
3Press ENTER/BRIGHTNESS.
The displayed wake-up sound number will sound.
4Press Jog lever v (up) or V (down) to select the desired wake-up sound.
1: Buzzer
2: “Four seasons: Spring” Antonio Lucio Vivaldi
3: “For Eliza” Ludwig van Beethoven
5Press ENTER/BRIGHTNESS.
Two short beeps will confirm the setting, and theALARM A or B
display will disappear.
To Use the Radio and Buzzer Alarm
1Set both alarm times for ALARM Aor B.
(see above).
2Press ALARMAor ALARM B.
The ALARM Aor B display will be turned on.
If the same alarm time is set for both Alarm Aand B, AlarmA takes
priority.
To Doze for a Few More Minutes
Press SNOOZE/DATE/SLEEPOFF.
The radio or buzzer turns off but will automatically come on again after
about 10 minutes. Every time you press SNOOZE/DATE/SLEEPOFF,
the snooze time changes as follows:
10 t 20 t 30 t 40 t 10 t
The display shows the snooze time for a few seconds and returns to show
the current time. When you press SNOOZE/DATE/SLEEP OFF after
the current time appeared, the snooze time starts from 10 minutes
again.
The maximum length of the snooze time is 60 minutes.
To Stop the Alarm
Press OFF/ALARM RESET to turn off the alarm.
The alarm will come on again at the same time the next day.
To Deactivate the Alarm
Press ALARMAor ALARM B.
The ALARMA or B display turns off.
Using the NAPTimer
(Count DownTimer)
The NAP timer sounds the buzzer after a preset time duration.
Press NAP repeatedly until the desired minutes are displayed.
Every press changes the display as follows:
You will hear two beeps when the display turns from “OFF” to “10”.
“ ” appears and the NAP time is displayed for a few seconds.
NAP timer starts counting down the NAP time.
When selected NAP time has passed, the beep sound comes on, and
“” on the display flash.
The buzzer is turned off automatically after about 60 minutes.
To Stop the NAPTimer
Press NAPor OFF/ALARM RESET to turn off the buzzer.
To Deactive the NAPTimer
PressNAP.
“ ” goes off in the display.
Setting the SleepTimer
You can fall asleep to the radio using the built-in sleep timer that turns off
the radio automatically after a preset duration.
Press SLEEP.
The radio turns on. You can set the sleep timer to durations of 90, 60, 30,
or 15 minutes. Every push changes the display as follows:
You will hear two beeps when the display turns from “OFF” to “90”.
“SLEEP” will appear in the display when the duration time is set.
The radio will play for the duration you set, then shut off.
• To turn off the radio before the preset time, press SNOOZE/DATE/
SLEEPOFF.
To Use Both SleepTimer and Alarm
You can fall asleep to the radio and also be awakened by the radio or
buzzer alarm at a preset time.
1Set the alarm. (See “Setting the Alarm”.)
2Set the sleep timer. (See “Setting the Sleep Timer”.)
tOFF t 10 t 20 t 30
120 T 90 T 60
tOFF t 90 t 60
15 T 30

ICF-C273
6
SECTION 2
DISASSEMBLY
Note : Follow the disassembly procedure in the numerical order given.
2-2. SWITCH BOARD, CABINET (UPPER)
rThe equipment can be removed using the following procedure.
2-2. CABINET (LOWER)
(Page 6)
2-3. ALARM BOARD,
JOG BOARD
(Page 7)
SET
2-2. SWITCH BOARD,
CABINET (UPPER)
(Page 6)
2-4. MAIN BOARD
(Page 7) 2-5. TRANS BOARD (Page 8)
2-1. DISASSEMBLY FLOW
qs cabinet (upper)
qa SWITCH baord
9 three screws
0 Remove solder(seven places)
5 CN251
2 two screws (B2.6)
1 three screws (B2.6)
3 three craws
6 two craws
8 CN501
cabinet (lower)
4
7

ICF-C273
7
2-3. ALARM BOARD, JOG BOARD
2-4. MIAN BOARD
4 two screws
3 cover (jog)
2 screw
8 JOG baord
7 screw
6 arm (jog)
5 ALARM board
1 two screws
Cabinet (upper)
1 screw (B2.6)
2 power cord retainer board
On assembling, set antenna (wire) a
s
shown in the figure.
antenna (wire)
4 CN201
7 MAIN board
3 screw
5 craw
6

ICF-C273
8
2-5.TRANS BOARD
4 TRANS board
1 screw (B2.6)
2 power cord retainer boar
d
3

ICF-C273
9
SECTION 3
ELECTRICAL ADJUSTMENTS
BAND button : AM
Volume : MIN
3-1.TUNER SECTION
AM Section
FM Section
BAND button : FM
Volume : MIN
Put the lead-wir
e
antenna close to
the set.
AM RF signal
generator
30% amplitude modulation by 400Hz
signal.
Output level : as low as possible
W2
FM
wire
antenna
FM RF signal
generator
22.5kHz frequency deviation by
400Hz signal.
Output level : as low as possible
0.01 uF
• Repeat the procedures in each adjustment several times, and the
frequency coverage and tracking adjustments should be finally
done by the trimmer capacitors.
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter.
T1 450kHz
AM FREQUENCY COVERAGE ADJUSTMENT
Adjust part Frequency display
L4 531kHz
reading on digital
voltmeter.
Adjustment value: 2.7V
Standaed value: 2.5 to 2.9V
AMTRACKING ADJUSTMENT
Adjust for a maximum reading on level meter.
L 1 585kHz
CT1 1,485kHz
Frequency Coverage Adjustment
Connect Location :
FM FREQUENCY COVERAGE CONFIRMATION
Adjust part Frequency display
Confirmation 87.5MHz 3.0 to 4.0V
Confirmation 108MHz 9.5 to 10.5V
reading on digital
voltmeter
FMTRACKING ADJUSTMENT
Adjust for a maximum reading on level meter.
L2 87.5MHz
CT3 108MHz
32 Ω
level mete
r
set
J251 (phones)
+
–
0dB=1µV
L2 : FM tracking
adjustment
L1 : AM Tracking
adjustment
CT1 : AM tracking
adjustment
L4 : AM Frequency
coverage
adjustment CT3 : FM tracking
adjustment
T1 : AM IF
adjustment
MAIN BOARD (SIDE A)
JW3 (VT)
digital voltmeter
(DC range)

ICF-C273
10
SECTION 4
DIAGRAMS
•Circuit Boards Location
MAIN baor
d
JOG baord
ALARM baord
TRANS baord
SWITCH baord

11
11
ICF-C273
Note:
•X: parts extracted from the component side.
•f: internal component.
•: Pattern from the side which enables seeing.
Note:
•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.
•f: internal component.
Note: The components identified by mark 0or dotted
line with mark 0are critical for safety.
Replace only with part number specified.
•Voltages are dc with respect to ground under no-signal
conditions.
no mark : FM
():AM
•Voltagesare takenwitha VOM(Inputimpedance 10MΩ).
Voltage variations may be noted due to normal produc-
tion tolerances.
•Signal path.
F: FM
e: AM
4-1. IC Block Diagrams
IC1 CXA1019M
IC51 LC7213M-TLM-E
GND GND
FM DISCRI
NF
VOL
AM OSC
AFC
FM OSC
REG OUT
FM RF
AM RF IN
N. C
FM RF IN
FE GND
MIX OUT
21222324252627
2829
30
235
4678910
111 12 13 14 15
16
17
18
1920
AF POWER AMP
AM IF DET AGC
AM FE
FM
DISCRIMINATOR
FM FE
TUNING
METER
FM IF
GND GND AF OUT Vcc RIPPLE FILTER AF IN DET OUT AFC AGC AFC AGC IF GND METER N. C FM IF IN AM IF IN FM/AM BAND SELECT
OCB
I/F
1
CE
2
DI
3
CL
4
DO
16
PD VSS
15
VDD
14 13
MO/ST
20
X OUT
18
LP-OU
T
17
LP-IN
19
X IN
5
NUTE
6
MW/LW
7
BAND
8
ST-IND
9
BAND
DATA SHIFT REGISTER
LATCH
UNIVERSAL
CONTROLER
SWALLOW COUNTER
1/16. 1/17 4 BITS
12 BIT PROGRAMBLE
DIVIDER
UNLOCK
DETECTOR
PHASE DETECTOR
CHARGE PUMP
FILTER
REFERENCE
DIVIDER
POWER
ON
RESET
1/2
10
IF-IN
12
FM-IN AM-IN
11

ICF-C273
12
12
4-2. BLOCK DIAGRAM
19
20
16
12
5
1
2
3
11
10
9
12
8
3 4
16
17 23 24 27
5172
70 71
484950 65 66 67 68
X101
32.768MHz
SYSTEM
CONTROL
IC101
X51
75kHz
W2
FM
WIRE
ANTENNA
XIN
FM RF IN
FM RF
FM OSC
BAND SELECT
AM OSC
AM RF IN
REG OUT
AOUT
AIN
XIN
CE
DT
CL
CE DT CL
L1
AM
FERRITE-ROD
ANTENNA
L1,CT1
AM TRACKING
PD
XIN
NF
FM IN
AM IN
74 75 536 - 9 10 - 37
X102
4.192MHz
54 55 56 57 61 62 63 64 76 5
RESET
IC102
18
IC
A OUT
D52
D106
D53
14
IC
VDD
LCD101
LCD DISPLAY
VDD
(IC101)
VOLTAG
DET
Q101
4V REG
Q201,D203
REG
Q202,D204
RECT
D205
FM
FROT END
SWITCH
Q3
VOLUME
RV1
T1
AM IF CF1
CF2
MUTE
Q4
FM IF
DISCRI
AF
POWER
AMP
SPEAKER
SP1
LED
SWITCH
Q102,103
LED
SDRIVE
Q108
LED
DRIVE
Q109
LED
SWITCH
Q104-107
AM IF
DET
FM/AM
FE OUT
AM
IF
IN
FM
IF
IN AF IN
FM/AM
FRONT-END,IF AMP
DET,POWER AMP
IC1
DET
OUT
AF
OUT
T201
POWER
TRANSFORMER
RECT
D201
RECT
D202,D51
46
1
2
VOLTAG
DET
IC103
1
5
18
17
5
15
7
AM
FROT END
14
D108 +4V
D109
D110
D111
ALARM A
ALARM A
ALARM B
+4V
+B
LIGHT1,2
LIGHT1,2
CE(R)
DATA(R)
CLOCK(R)
XT1 XT2 X1 X2
COM0
I
COM3
SEG0
I
SEG27
KS0 KS1 KS2 KS3(S0) KS4(S1) KS0 KS1 KS2 KS3 RESER VLC0 VDET
MUTE
BUZZER
LIGHT1 LIGHT2
ALM-A ALM-B
D112
ALARM B
D108-110
BACK LIGHT
AC IN
L2,CT3
FM TRACKING
L4
AM FREQUENCY
COVERAGE
L3
FM
OSC
L2
D3
CT1
D2CT3
FM
OSC
KEY MATRIX
S101-114(SWITCH (A))
S115-117(ALARM)
S118,119(JOG)
PLL FREQUENCY
SYNTHESIZER
IC51
•Signal path.
F: FM
e: AM

13
13
ICF-C273
4-3. PRINTED WIRING BOARD – MAIN SECTION (1/2) –
W2
FM
WIRE
ANTENNA
L1
AM
FERRITE-BAR
ANTENNA
Q101 Q103 Q102
BCE
ECBECB
Q104
Q4
BCE
Q105
BCE
Q106
BCE
Q108
BCE
BCE
Q3
BCE
Q109
BCE
Q107
BCE
R106
R134
R133
R101
CN501
CN201
R132
R104
R103
R123
R176 R175
R177
R178
R105
R112
R110
R17
R53
IC51
R55
R54
R10
R6
BPF1
R107
R108
R191
ALARM A
R213R214
R192
R180 R179
R146
R156
R15
R114 R115
R102
R119
R125 R129 R130 R126
R136
R135
R122
R109
R172
R171 R170 R169
R168 R167
R121
R166 R165 R164 R163 R162 R161
R173
R174
R52
R202
R201 R58
R60 R59
R51
R203
R56
R9
R7
R8
R3
R16
R5
R4
R12 R11
R120
R215
R138
R211
R111
R160R149
R141R151
R157
R159
R144 R145 R147 R148 R142
R190 R189 R188 R187 R186 R185 R184 R183 R182 R181
R152 R153
R154 R155 R19
R18
R137
R131 R128
C107
C109
C108
C201
C105
C106
C102
C136
C124
C138
C21
C51 C53 C54
C9
C202
C52
C251
C22 C35
C20
C7
C24
C25
C31
C6
C16
C113
C119
C111 C112 C115
C120
C121
C117
C122 C123
C118
C132
C134 C133
C101
C30 C103
C137
C135
C26
C23
C58 C56
C55
C61
C34
CN251
C60
C3
C4
C8
C5
C32
C13
C14 C17
R150
C131
C33
D105
D103
D102
D101
D104
D205
D203
D204
D51
D2
D111
X102
ALARM B
D112
D109
D110
IC101
D108
E C B
Q202
E C B
Q201
D201
D52
D202
D53
D106
C110
C18
C19
C11
C12
C15
C10
C203
C206
C205
C57
C204
SP1
SPEAKER
RED
GRY
RED
GRY
X51
IC1
CF1
T1
CF3
CF2
CT3 L2
RV1
VOLUME
IC102
IC103
LCD101
LIQUID CRYSTAL DISPLAY
JC101
11
(11)
1-861-130-
BOARDMAIN
JC51
JC2
JC1
D3
L4
D4
CT1
L3
80
1
1
20 21
44
40
61 60
3
1
2
34
45
X101
1
10
10
10 10
1
14
15 28
JC102
PS201
RED
BLK
GRY
TRANS
BOARD
(Page 14)
SWITCH
BOARD
(Page 14)
B A
1
2
8
9
23 4 5 6 7 8910 11
A
1
B
C
D
E
F
G
H
D2 C-4
D3 C-4
D4 B-5
D51 C-7
D52 D-6
D53 D-6
D101 F-9
D102 F-9
D103 F-9
D104 F-10
D105 F-10
D106 E-4
D108 G-10
D109 F-9
D110 G-7
D111 F-4
D112 G-4
D201 E-9
D202 C-8
D203 D-7
D204 D-7
D205 G-11
IC1 D-4
IC51 C-6
IC101 F-6
IC102 F-4
IC103 G-4
Q3 D-2
Q4 E-2
Q101 F-9
Q102 F-11
Q103 F-11
Q104 G-2
Q105 G-2
Q106 G-2
Q107 H-3
Q108 G-4
Q109 G-4
Q201 D-6
Q202 D-6
Ref. No. Location
zSemiconductor
Location

ICF-C273
14
14
4-4. PRINTED WIRING BOARD – MAIN SECTION (2/2) –
BOARDSWITCH
11
(11)
1-861-132-
RED
BLK
GRY
GRY
S103
CLOCK
STATION • SELECT/PRESET
S114
D.S.T
SUMMERT
S112
5
S111
4
S110
3
S109
2
S108
1
W500
S106
SLEEP
S105
OFF/ALARM RESET
S104
ON/BAND
S113
SNOOZE/DATE/
SLEEP OGG
S102
TUNING
-
S101
TUNING
+
S107
NAP
RED
BLK
GRY
W503-1W503-2
S117
ENTER/BRIGHTNESS
S115
ALARM A
S116
ALARM B
R197 R196 R198
RED
BLK
GRY
GRY
BOARDALARM
11
(11)
1-861-136-
R199
R200
RED
BLK
GRY
S119
TIME SET -
S118
TIME SET +
BOARDJOG
11
(11)
1-861-135-
RED
BLK
GRY
T201
POWER TRANSFORMER
W201
P201
AC IN
BOARDTRANS
11
(11)
1-861-131-
A
MAIN
BOARD
(Page 13)
B
MAIN
BOARD
(Page 13)
23 4 5 6 7 8910
A
1
B
C
D
E
F
G
H

15
15
ICF-C273
4-5. SCHEMATIC DIAGRAM – MAIN SECTION (1/2)–
IC1
IC51
D2
D3
D4
D51
D52
D53
D205
D201
D202
D203
CT1
CT3
C3
C4
C5
C6
C8
C22
C34
C24
L4
C31
C33
C10
C32 C21
C23
C26
C30
C11 C12
C13
C14 C15
C18 C19
C16
C17
L1
R3
L2
R6
L3
C20 R8
R9
C7
R11
R12
CF3
R17
R18
R19
CF1
CF2
T1
R4
R5
C201
C202 C203 C204 C205
R201 R202
R203
C206
C52
R58 R59 R60
R56
C55
C57
C58
R54
R55
X51
JC51 C60
RV1
R16
JC2
BPF1
R53
C9
C25 R15
W2
CN251
CN201
JC1
R7
P201
C51
C53
C54
C56
C61
D204
R10
R51
Q202
Q201
Q4
Q3
R52
C35
PS201
C251
CXA1019M
LC72137M-TLM-E
HVU202ATRU
HVU202ATRU
KV1610STL1-2
UDZSTE-1713B
1SS133T-77
1SS133T-77
1SS355TE-17
1N4002B
1SS133T-77
UDZSTE-174.7B
100p
1000p
10p
0.01
3p
220p
220p
10p 0.1
0.022
10
50V
0.01 0.01
1
100p
0.01
4.7
50V 10
50V
0.022
0.22 10
50V
470
6.3V
220
10V
1
1
100k 4.7k
0.022 100k
10k
1000p
47
100
1k
100k
47k
2.2k
470
0.01
0.01 1000
10V
220
10V
470
6.3V
470 470
4.7k
220
25V 0.01
1k 1k 1k
220
0.22
220
10V
0.01
10k
10k
75kHz
0.01
50k
10k
22k
0.01
5p 470k
2P
3P
1k
10p
10p
6p
470p
0.1
UDZSTE-175.1B
2.2M
2.2k
2SC2001TP-K1K2
REG
2SC2001TP-K1K2
REG
2SC4081-R
MUTE
2SA1576A-T106-R
SWITCH
10
1000p
0.4A/90V
0.01
BUZZER
VDD
MUTE
V DET
CE
DATA
CLK
LED
GND
FM
TRACKING
TRACKING
AM
L1,CT1
POWER
TRANSFORMER
T201
PLL FRQUENCY
SYNTHESIZER
L2,CT3
AC IN
AM
ANTENNA
FERRITE-BAR
AM
FREQUENCY
COVERAGE
L4

ICF-C273
16
16
4-6. SCHEMATIC DIAGRAM – MAIN SECTION (2/2)–
D101
D102
D103
D104
D105
C105 C106 C107 C108 C109
R132
R133
R134
R135
R136
R102
R103
R104
R105
Q102 Q103 Q104 Q105 Q106 Q107
D108
R121 R122 R123
D110
D111 D112
C135 C136 C137 C138
S102
S104 S105 S106
S107 S108 S109
S110 S111 S112
S113 S114
S115
S116
S117
JW121
JW122
R193
R194
R195
R196
R197
R198
R199
R200
R141 R151
R125
R126
R128 R131 R146 R149 R156 R159
R129 R130 R147 R148
C131 C132
R150 R160
C133 C134
R114
R109
R101
R110 R112
C111 C112
X101
R138
C115
R120
X102
R107
R108
C119
C120
R111
C117
R211
R213
R214
R215
C121
C122
C123
C113 C110 C118
IC101
IC102
C101
C102
C103
R161
R162
R163
R164
R165
R166
R167
R168
R169
R170
R171
R172
R173
R174
R175
R176
R177
R178
R179
R180
R181
R182
R183
R184
R185
R186
R187
R188
R189
R190
R191
R192
LCD101
CN501
JC102
W500
D106
R157
C124
R115
R119
Q109
Q108
IC103
S118
S119
S103
S101
D109
Q101
R106
R137
R142 R144
R145
R152 R153
R154 R155
1SS355TE
1SS355TE
1SS355TE
1SS355TE
1SS355TE
470p 470p 470p 470p 470p
4.7k
4.7k
4.7k
4.7k
4.7k
1k
1k
1k
4.7k
2SC4081 2SC4081 2SC4081 2SC4081 2SC4081 2SC4081
SLP-235A-51S1E
10 10 10
SLP-235A-51S1E
SLP-235A-51S1E SLP-235A-51S1E
0.01 0.01 0.01 0.01
10k
10k
10k
10k
10k
10k
10k
10k
10 10
470
220
4.7k 4.7k 4.7k 4.7k 4.7k 4.7k
100 47 470 220
0.01 0.01
4.7k 4.7k
0.1 0.1
100k
100k
1k
1k 1k
22p 22p
32.768kHz
220k
1
10
4.191MHz
10k
10k
0.01
0.01
1M
0.01
22k
100k
100k
100k
0.1
0.1
0.1
0.1 1000
6.3V
0.01
XC61CN2002NR
47p
100p
100p
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
10k
9P
9P
1SS133T-77
100
0.1
100k
100k
2SC4081
LED DRIVE
2SC4081
LED DRIVE
XC6201P302MR
SLP-235A-51S1E
DTC144EUA
VOLTAGE
DETECT
10k
2.2k 1k
2.2k
2.2k 4.7k
1k 2.2k
DATA
CLK
BUZZER
CE
GND
MUTE
V DET
LED
VDD
ALM A
ALM B
LIGHT1
LIGHT2
SEG0
SEG1
SEG2
SEG3
SEG4
SEG5
SEG6
SEG7
SEG8
SEG9
SEG10
SEG11
SEG12
SEG13
SEG14
SEG15
SEG16
COM0
COM1
COM2
COM3
SEG0
SEG1
SEG2
SEG3
SEG4
SEG5
SEG6
SEG7
SEG8
SEG9
SEG10
SEG11
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
SEG22
SEG23
SEG24
SEG25
SEG26
SEG27
COM0
COM1
COM2
COM3
SEG27
SEG26
SEG25
SEG24
SEG23
SEG22
SEG21
SEG20
SEG19
SEG18
SEG17
LIGHT2
LIGHT1
ALM A
ALM B
LED SWITCH
Q102-107
ALARMA ALARMB
D108-110
(BACK LIGHT)
SYSTEM
CONTROL
VOLTAGE
DETECT
RESET
TUNUNG
+
ON/BAND
NAP
3
TUNUNG
-
OFF/ALARMRESET
1
4
CLOCK
SLEEP
2
5
D.S.T
SUMMERT
ALARMA
ALARMB
ENTER/BRIGHTNESS
TIME SET
TIME SET
0.22u
SNOOZE/DATE/SLEEP OFF

ICF-C273
17
SECTION 5
EXPLODEDVIEW
NOTE :
•-XX, -X mean standardized parts, so they
may have some difference from the original
one.
•Color indication of Appearance Parts
Example :
KNOB, BALANCE (WHITE) ••• (RED)
↑↑
Parts color Cabinet's color
•Items marked “ * ”are not stocked since they
are seldom required for routine service. Some
delay should be anticipated when ordering
these items.
•The mechanical parts with no reference
number in the exploded views are not
supplied.
•Accessories and packing materials are given
in the last of this parts list.
Ref. No. Part No. Description Remarks Ref. No. Part No. Description Remarks
5-1. CABINET (UPPER) SECTION
a
a
1
1
2
77
7
3
4
5
6
5
12
8
10
11
SP1
9
13-254-141-01 SCREW (B2.6), (+) BV TAPPING
23-261-891-01 CHASSIS
*31-861-132-11 SWITCH BOARD
43-252-827-01 SCREW (B2.6), (+) BV TAPPING
53-259-210-01 CUSHION (H)
6X-2022-166-1 CABINET, UPPER ASSY
73-254-070-01 SCREW
*81-861-136-11 ALARM BOARD
9X-2022-167-1 COVER (JOG) ASSY
*10 1-861-135-11 JOG BOARD
11 3-261-887-01 ARM (JOG)
12 3-261-888-01 KNOB (JOG)
SP1 1-529-456-13 SPEAKER (6.6cm)
The components identified by mark 0
or dotted line with mark 0are critical
for safety.
Replace only with part number specified.

ICF-C273
18
5-2. CABINET (LOWER) SECTION
52
51
52
53
54
55
56
57
59
58
56 56
P201
T201
LCD101
not supplied
not supplied
not supplied
not supplie
d
W2
L1
not supplied
Ref. No. Part No. Description Remarks Ref. No. Part No. Description Remarks
51 3-261-883-21 CABINET (LOWER)
52 3-246-344-11 FOOT, RUBBER
*53 1-861-131-11 TRANS BOARD
54 3-261-890-01 HOLDER (LCD)
55 3-254-070-01 SCREW
56 3-252-827-01 SCREW (B2.6), (+) BV TAPPING
57 3-261-892-01 HOLDER (ANTENNA)
58 3-382-175-21 KNOB (V)
59 A-4541-926-A MAIN BOARD COMPLETE
L1 1-428-951-21 COIL, FERRITE-ROD ANTENNA (MW)
LCD101 1-805-524-11 DISPLAY PANEL, LIQUID CRYSTAL
0P201 1-790-431-21 POWER SUPPLY CORD (7.5A/250V)
0T201 1-435-504-11 TRANSFORMER, POWER
W2 1-754-330-11 ANTENNA (WIRE)
The components identified by mark 0
or dotted line with mark 0are critical
for safety.
Replace only with part number specified.

ICF-C273
19
NOTE :
•Due to standardization, replacements in the
parts list may be different from the parts
specified in the diagrams or the components
used on the set.
•-XX, -X mean standardized parts, so they
may have some difference from the original
one.
•RESISTORS
All resistors are in ohms
METAL : Metal-film resistor
METAL OXIDE :Metal oxide-film resistor
F : nonflammable
•Items marked “ * ”are not stocked since
they are seldom required for routine service.
Some delay should be anticipated when
ordering these items.
•SEMICONDUCTORS
In each case, u : µ, for example :
uA.... : µA.... , uPA.... : µPA....
uPB.... : µPB.... , uPC.... : µPC....
uPD.... : µPD....
•CAPACITORS
uF : µF
•COILS
uH : µH
When indicating parts by reference num-
ber, please include the board.
SECTION 6
ELECTRICAL PARTS LIST
Ref. No. Part No. Description Remark Ref. No. Part No. Description Remark
The components identified by mark 0
or dotted line with mark 0are critical
for safety.
Replace only with part number specified.
*1-861-136-11 ALARM BOARD
***********
< RESISTOR >
R196 1-216-833-11 METAL CHIP 10K 5% 1/10W
R197 1-216-833-11 METAL CHIP 10K 5% 1/10W
R198 1-216-833-11 METAL CHIP 10K 5% 1/10W
< SWITCH >
S115 1-771-550-11 SWITCH, TACTILE (ALARM A)
S116 1-771-550-11 SWITCH, TACTILE (ALARM B)
S117 1-771-550-11 SWITCH, TACTILE (ENTER/BRIGHTNESS)
************************************************************
*1-861-135-11 JOG BOARD
*********
< RESISTOR >
R199 1-216-833-11 METAL CHIP 10K 5% 1/10W
R200 1-216-833-11 METAL CHIP 10K 5% 1/10W
< SWITCH >
S118 1-554-937-11 SWITCH, TACTILE (TIME SET +)
S119 1-554-937-11 SWITCH, TACTILE (TIME SET -)
************************************************************
A-4541-926-A MAIN BOARD, COMPLETE
**********
3-252-827-01 SCREW (B2.6), (+) BV TAPPING
3-261-890-01 HOLDER (LCD)
3-261-892-01 HOLDER (ANTENNA)
3-382-175-21 KNOB (V)
< FILTER >
BPF1 1-236-022-11 FILTER, BAND PASS
< CAPACITOR >
C3 1-162-927-11 CERAMIC CHIP 100PF 5% 50V
C4 1-115-416-11 CERAMIC CHIP 0.001uF 5% 25V
C5 1-162-915-11 CERAMIC CHIP 10PF 0.5PF 50V
C6 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C7 1-115-416-11 CERAMIC CHIP 0.001uF 5% 25V
C8 1-162-908-11 CERAMIC CHIP 3PF 0.25PF 50V
C9 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C10 1-126-964-11 ELECT 10uF 20% 50V
C11 1-126-963-11 ELECT 4.7uF 20% 50V
C12 1-126-964-11 ELECT 10uF 20% 50V
C13 1-164-227-11 CERAMIC CHIP 0.022uF 10% 25V
C14 1-115-467-11 CERAMIC CHIP 0.22uF 10% 10V
C15 1-126-964-11 ELECT 10uF 20% 50V
C16 1-125-837-91 CERAMIC CHIP 1uF 10% 6.3V
C17 1-125-837-91 CERAMIC CHIP 1uF 10% 6.3V
C18 1-126-935-11 ELECT 470uF 20% 16V
C19 1-126-923-91 ELECT 220uF 20% 10V
C20 1-164-227-11 CERAMIC CHIP 0.022uF 10% 25V
C21 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C22 1-164-230-11 CERAMIC CHIP 220PF 5% 50V
C23 1-125-837-91 CERAMIC CHIP 1uF 10% 6.3V
C24 1-162-915-11 CERAMIC CHIP 10PF 0.5PF 50V
C25 1-162-910-11 CERAMIC CHIP 5PF 0.25PF 50V
C26 1-162-927-11 CERAMIC CHIP 100PF 5% 50V
C30 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C31 1-107-826-11 CERAMIC CHIP 0.1uF 10% 16V
C32 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C33 1-164-227-11 CERAMIC CHIP 0.022uF 10% 25V
C34 1-164-230-11 CERAMIC CHIP 220PF 5% 50V
C35 1-115-416-11 CERAMIC CHIP 0.001uF 5% 25V
C51 1-162-915-11 CERAMIC CHIP 10PF 0.5PF 50V
C52 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C53 1-162-915-11 CERAMIC CHIP 10PF 0.5PF 50V
C54 1-162-911-11 CERAMIC CHIP 6PF 0.5PF 50V
C55 1-115-467-11 CERAMIC CHIP 0.22uF 10% 10V
C56 1-164-315-11 CERAMIC CHIP 470PF 5% 50V
C57 1-126-923-91 ELECT 220uF 20% 10V
C58 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C60 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C61 1-107-826-11 CERAMIC CHIP 0.1uF 10% 16V
C101 1-162-923-11 CERAMIC CHIP 47PF 5% 50V
C102 1-162-927-11 CERAMIC CHIP 100PF 5% 50V
C103 1-162-927-11 CERAMIC CHIP 100PF 5% 50V
C105 1-164-315-11 CERAMIC CHIP 470PF 5% 50V
C106 1-164-315-11 CERAMIC CHIP 470PF 5% 50V
C107 1-164-315-11 CERAMIC CHIP 470PF 5% 50V
C108 1-164-315-11 CERAMIC CHIP 470PF 5% 50V
C109 1-164-315-11 CERAMIC CHIP 470PF 5% 50V
C110 1-126-916-11 ELECT 1000uF 20% 6.3V
C111 1-162-919-11 CERAMIC CHIP 22PF 5% 50V
C112 1-162-919-11 CERAMIC CHIP 22PF 5% 50V
C113 1-107-826-11 CERAMIC CHIP 0.1uF 10% 16V
C115 1-125-837-91 CERAMIC CHIP 1uF 10% 6.3V
C117 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C118 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
ALARM JOG MAIN

ICF-C273
20
Ref. No. Part No. Description Remark Ref. No. Part No. Description Remark
MAIN
C119 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C120 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C121 1-107-826-11 CERAMIC CHIP 0.1uF 10% 16V
C122 1-107-826-11 CERAMIC CHIP 0.1uF 10% 16V
C123 1-107-826-11 CERAMIC CHIP 0.1uF 10% 16V
C124 1-107-826-11 CERAMIC CHIP 0.1uF 10% 16V
C131 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C132 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C133 1-164-156-11 CERAMIC CHIP 0.1uF 25V
C134 1-164-156-11 CERAMIC CHIP 0.1uF 25V
C135 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C136 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C137 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C138 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C201 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C202 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
C203 1-126-926-11 ELECT 1000uF 20% 10V
C204 1-126-934-11 ELECT 220uF 20% 16V
C205 1-126-935-11 ELECT 470uF 20% 16V
C206 1-104-666-11 ELECT 220uF 20% 25V
C251 1-162-970-11 CERAMIC CHIP 0.01uF 10% 25V
< FILTER >
*CF1 1-577-319-11 FILTER, CERAMIC
CF2 1-579-632-41 FILTER, CERAMIC
CF3 1-579-632-41 FILTER, CERAMIC
< CONNECTOR >
CN201 1-568-269-11 SOCKET, CONNECTOR 3P
*CN251 1-568-268-11 SOCKET, CONNECTOR 2P
CN501 1-770-640-11 CONNECTOR, FFC/FPC 9P
< TRIMMER >
CT1 1-141-299-11 CAP, CERAMIC TRIMMER 5PF
(AM TRACKING)
CT3 1-141-304-21 CAP, CERAMIC TRIMMER 10PF
(FM TRACKING)
< DIODE >
D2 8-719-084-67 DIODE HVU202ATRU
D3 8-719-084-67 DIODE HVU202ATRU
D4 6-500-169-01 DIODE KV1610STL1-2
D51 8-719-083-63 DIODE UDZSTE-1713B
D52 8-719-991-33 DIODE 1SS133T-77
D53 8-719-991-33 DIODE 1SS133T-77
D101 8-719-988-61 DIODE 1SS355TE-17
D102 8-719-988-61 DIODE 1SS355TE-17
D103 8-719-988-61 DIODE 1SS355TE-17
D104 8-719-988-61 DIODE 1SS355TE-17
D105 8-719-988-61 DIODE 1SS355TE-17
D106 8-719-991-33 DIODE 1SS133T-77
D108 6-500-920-01 DIODE SLP-235A-51S1E
D109 6-500-920-01 DIODE SLP-235A-51S1E
D110 6-500-920-01 DIODE SLP-235A-51S1E
D111 6-500-920-01 DIODE SLP-235A-51S1E
D112 6-500-920-01 DIODE SLP-235A-51S1E
D201 8-719-063-79 DIODE 1N4002B
D202 8-719-991-33 DIODE 1SS133T-77
D203 8-719-083-60 DIODE UDZSTE-174.7B
D204 8-719-069-54 DIODE UDZSTE-175.1B
D205 8-719-988-61 DIODE 1SS355TE-17
< IC >
IC1 8-752-050-16 IC CXA1019M
IC51 8-759-483-40 IC LC72137M-TLM-E
IC101 6-803-950-01 IC uPD789477GC-A41-8BT
IC102 6-702-604-01 IC XC61CN2002NR
IC103 6-703-937-01 IC XC6201P302MR
< SHORT >
JC1 1-216-864-11 SHORT CHIP 0
JC2 1-216-864-11 SHORT CHIP 0
JC51 1-216-864-11 SHORT CHIP 0
JC101 1-216-864-11 SHORT CHIP 0
JC102 1-216-864-11 SHORT CHIP 0
< COIL >
L1 1-428-951-21 COIL, FERRITE-ROD ANTENNA (MW)
L2 1-406-922-11 COIL, AIR-CORE
L3 1-414-690-21 INDUCTOR 82nH
L4 1-406-485-11 COIL (OSC)
< LIQUID CRYSTAL DISPLAY >
LCD101 1-805-524-11 DISPLAY PANEL, LIQUID CRYSTAL
< IC LINK >
0PS201 1-533-587-21 IC LINK 0.4A 90V
< TRANSISTOR >
Q3 8-729-026-52 TRANSISTOR 2SA1576A-T106-R
Q4 8-729-905-35 TRANSISTOR 2SC4081-R
Q101 8-729-029-14 TRANSISTOR DTC144EUA-T106
Q102 8-729-905-35 TRANSISTOR 2SC4081-R
Q103 8-729-905-35 TRANSISTOR 2SC4081-R
Q104 8-729-905-35 TRANSISTOR 2SC4081-R
Q105 8-729-905-35 TRANSISTOR 2SC4081-R
Q106 8-729-905-35 TRANSISTOR 2SC4081-R
Q107 8-729-905-35 TRANSISTOR 2SC4081-R
Q108 8-729-905-35 TRANSISTOR 2SC4081-R
Q109 8-729-905-35 TRANSISTOR 2SC4081-R
Q201 8-729-011-92 TRANSISTOR 2SC2001TP-K1K2
Q202 8-729-011-92 TRANSISTOR 2SC2001TP-K1K2
< RESISTOR >
R3 1-216-845-11 METAL CHIP 100K 5% 1/10W
R4 1-216-825-11 METAL CHIP 2.2K 5% 1/10W
R5 1-216-817-11 METAL CHIP 470 5% 1/10W
R6 1-216-829-11 METAL CHIP 4.7K 5% 1/10W
R7 1-216-821-11 METAL CHIP 1K 5% 1/10W
R8 1-216-845-11 METAL CHIP 100K 5% 1/10W
R9 1-216-833-11 METAL CHIP 10K 5% 1/10W
R10 1-216-861-11 METAL CHIP 2.2M 5% 1/10W
R11 1-216-805-11 METAL CHIP 47 5% 1/10W
R12 1-216-809-11 METAL CHIP 100 5% 1/10W
R15 1-216-853-11 METAL CHIP 470K 5% 1/10W
R16 1-216-833-11 METAL CHIP 10K 5% 1/10W
R17 1-216-821-11 METAL CHIP 1K 5% 1/10W
R18 1-216-845-11 METAL CHIP 100K 5% 1/10W
The components identified by mark 0
or dotted line with mark 0are critical
for safety.
Replace only with part number specified.