Sony ICFC-723 Service manual

ICF-C723/C723L

SERVICE MANUAL

Ver 1.1

SPECIFICATIONS

Radio section

Frequency range :

US, Canadian model
Band ICF-C723 Channel step
FM 87.5– 108 MHz 0.1MHz
AM 530 – 1,710 kHz 10kHz

EXCEPT US, Canadian model
Band ICF-C723 ICF-C723L Channel step
FM 87.5– 108 MHz 87.5– 108 MHz 0.05MHz*
AM (MW) 531 – 1,602 kHz 530 – 1,602 kHz 9kHz
LW –––––––– 530 – 1,602 kHz 9kHz

* The frequency display is raised or lowerd by steps of

0.1MHz.
(Example : Frequency 88.05 MHz is displayed as “88.0
MHz”.)

US Model

Canadian Model

E Model

Australian Model

ICF-C723

UK Model

ICF-C723L

AEP Model

ICF-C723/C723L

General

Time display

US, Canadian, UK model 12-hour

EXCEPT US, Canadian, UK model 24-hour
Speaker Approx. 5.7 cm (2 1/4 in) dia.
Power output

100 mW (at 10% harmonic distortion)
Power requirements

US, Canadian model :120V AC, 60Hz

EXCEPT US, Canadian model : 220 – 230V AC, 50Hz
Dimensions

Approx. 181 x 103 x 133 mm (w/h/d)

(7 1/4 x 4 1/8 x 4 1/4 in) incl. projecting parts and controls
Mass Approx. 550 g (1 lb 3.4 oz)

Approx. 600 g (1 lb 5.2 oz) : ICF-C723L (UK model)

Design and specifications are subject to change without notice.

DIGITAL VOICE MEMO Recording section

Recording media

Built-in flash memory

Recording time

20 seconds

Frequecy response

400Hz – 2,700Hz

MICROFILM

ICF-C723

FM/AM PLL SYNTHESIZED CLOCK RADIO

ICF-C723L

FM/MW/LW PLL SYNTHESIZED CLOCK RADIO

TABLE OF CONTENTS

SAFETY CHECK-OUT

Specifications ........................................................................... 1

1. GENERAL

Location and Function of Controls .................................... 3

2. DISASSEMBLY

2-1. Cabinet (Upper) Removal........................................... 4

2-2. Microcomputer Board Removal ................................. 4

2-3. Main Board, Key Board, Transformer (Primary)

Board, Transformer (Secondary) Board Removal ...... 5

Installation Power Cord ..................................................... 5

3. ELECTRICAL ADJUSTMENT................................ 6

4. DIAGRAMS

4-1. Explanation of IC Terminal ........................................ 8

4-2. Printed Wiring Board (Microcomputer Section) ........ 9

4-3. Schematic Diagram ((Microcomputer Section).........11

4-4. Printed Wiring Board (Main Section)....................... 13

4-5. Schematic Diagram (Main Section) ......................... 15

5. EXPLODED VIEW..................................................... 18

6. ELECTRICAL PARTS LIST................................... 19

After correcting the original service problem, perform the
following safety check before releasing the set to the customer :
Check the antenna terminals, metal trim, “metallized” knobs,
screws, and all other exposed metal parts for AC leakage. Check
leakage as described below.

LEAKAGE TEST

The AC leakage from any exposed metal part to earth ground
and from all exposed metal parts to any exposed metal part
having a return to chassis, must not exceed 0.5mA (500
microampers).
Leakage current can be measured by any one of three methods.

1. A commercial leakage tester, such as the Simpson 229 or
RCA WT-540A. Follow the manufacturers’ instructions to
use these instruments.

2. A battery-operated AC milliammeter. The Data Precision 245
digital multimeter is suitable for this job.

3. Measuring the voltage drop across a resistor by means of a
VOM or battery-operated AC voltmeter. The “limit” indica­tion is 0.75V, so analog meters must have an accurate low­voltage scale. The Simpson 250 and Sanwa SH-63Trd are
examples of a passive VOM that is suitable. Nearly all
battery operated digital multimeters that have a 2V AC range
are suitable. (See Fig. A)

MODEL IDENTIFICATION

– Model Number Portion –
Carved on lower cabinet

MODEL NO.

ICF-C723
ICF-C723L

US, Canadian model : AC : 120V⁄60Hz 5W
AEP, UK, Italian,
E, Australian model : AC : 220 – 230V⁄50Hz 5W

• HOW TO CHANGE THE CERAMIC FILTER

This model is used two ceramic filters of CF1 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

Mark

Center

frequency

red 10.70MHz

CF3

CF1

blue 10.67MHz

orange 10.73MHz

black 10.64MHz
white 10.76MHz

To Exposed Metal
Parts on Set

1.5k

0.15

µ

F

Fig. A. Using an AC voltmeter to check AC leakage.

SAFETY-RELATED COMPONENT WARNING!!

COMPONENTS IDENTIFIED BY MARK ! OR DOTTED LINE WITH
MARK ! 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 MANUAL OR IN
SUPPLEMENTS PUBLISHED BY SONY.

ATTENTION AU COMPOSANT AYANT RAPPORT

LES COMPOSANTS IDENTIFIÉS P AR UNE MARQUE ! SUR LES
DIAGRAMMES SCHÉMA TIQUES ET LA LISTE DES PIÈCES SONT
CRITIQUES POUR LA SÉCURITÉ DE FONCTIONNEMENT. NE
REMPLACER CES COMPOSANTS QUE PAR DES PIÈCES SONY
DONT LES NUMÉROS SONT DONNÉS DANS CE MANUEL OU
DANS LES SUPPLÉMENTS PUBLIÉS PAR SONY.

À LA SÉCURITÉ!

Ω

Earth Ground

AC
voltmeter
(0.75V)

– 2 –

LOCATION AND FUNCTION OF CONTROLS

SECTION 1

GENERAL

*

* ICF-C723 : FM, AM

ICF-C723L : FM, MW, LW

– 3 –

SECTION 2

DISASSEMBLY

Note : Follow the disassembly procedure in the numerical order given.

2-1. CABINET (UPPER) REMOVAL

3

Cabinet (Upper)

Cabinet (lower)

4

2

Precision driver

2-2. MICROCOMPUTER BOARD REMOVAL

1

CN101

4

Claw

Microcomputer board

1

Screws +P (3x14)

Holder (transformer)

3

Claws

– 4 –

5

2

CN102

Cabinet (lower)

2-3. MAIN BOARD, KEY BOARD, TRANSFORMER (PRIMARY) BOARD,

d

TRANSFORMER (SECONDARY) BOARD, REMOVAL

1

Screws +P (3x14)

Shield case (transformer)

3

CN1

Power transformer (T201)

Main board

4

Claw

6

Claw

Key board

INSTALLATION POWER CORD

6

7

Claw

5

4

4

Claw

Claw

2

8

Transformer (primary) board

9

Transformer (secondary) boar

Cabinet (lower)

US model

Cabinet (lower)

power cord

– 5 –

EXCEPT US model

Cabinet (lower)

power cord

r

SECTION 3

ELECTRICAL ADJUSTMENTS

AM Section

Band button : AM (ICF-C723)

: MW or LW (ICF-C723L)

Volume : MAX

AM RF signal
generator

30% amplitude modulation by 400Hz
signal.
Output level : as low as possible

FM Section

Band button : FM
Volume : MAX

FM RF signal
generator

22.5kHz frequency
deviation by 400Hz signal.
Output level :
as low as possible

set

Put the lead-wire
antenna close to
the set.

0.01 F

FM ANT IN

level mete

8

Ω

speaker terminal

• Repeat the procedures in each adjustment several times, and the

frequency coverage and tracking adjustments should be finally
done by the trimmer capacitors.

( ): AEP, UK, Italian, Australian, E model only

AM IF ALIGNMENT

Adjust for a maximum reading on level meter.

T1 455kHz

AM <MW> FREQUENCY COVERAGE ADJUSTMENT

Adjust parts Frequecy display

L6 530kHz (531kHz)

confirmation 1,710kHz (1,602kHz)

µ

set

AM <MW> TRACKING ADJUSTMENT

Adjust for a maximum reading on level meter.

L3 :ICF-C723

L3–1 :ICF-C723L

CT1 1,490kHz (1,404kHz)

580kHz (621kHz)

Reading on digital

voltmeter

2.5 ± 0.1V (ICF-C723)

2.65 ± 0.1V (ICF-C723L)
Less than 11.0V

Standard 9.5V

(Less than 10.0V)

(Standard 9.0V)

ICF-C723L

LW FREQUENCY COVERAGE ADJUSTMENT

Adjust parts Frequecy display

confirmation 153kHz

CT4 279kHz 9.0 ± 0.1V

Reading on digital

voltmeter

More than 2.2V

(Standard 3V)

[MAIN BOARD] (Conductor side)

5

W705

4

C15

3

2

6

C55

1

JW13

digital

voltmeter

LW TRACKING ADJUSTMENT

Adjust for a maximum reading on level meter.

L3 – 2 162kHz

CT2 243kHz

FM FREQUENCY COVERAGE ADJUSTMENT

Adjust parts Frequecy display

L5 87.5MHz 3.0 ± 0.1V

confirmation 108.0MHz 10 ± 1V

FM TRACKING ADJUSTMENT

Adjust for a maximum reading on level meter.

L4 87.5MHz

CT3 108MHz

Reading on digital

Adjustment Location : Main board (See page 8)

voltmeter

– 6 –