Table Of Contents; To Change The Ceramic Filter - Sony ICF-C723 Service Manual

TABLE OF CONTENTS

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
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
MODEL IDENTIFICATION
- Model Number Portion -
Carved on lower cabinet
MODEL NO.
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
CF1
CF3
................................ 6
................................... 19
ICF-C723
ICF-C723L
Center
Mark
frequency
red 10.70MHz
blue 10.67MHz
orange 10.73MHz
black 10.64MHz
white 10.76MHz
SAFETY CHECK-OUT
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" indica-
tion is 0.75V, so analog meters must have an accurate low-
voltage 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)
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 PAR UNE MARQUE ! SUR LES
DIAGRAMMES SCHÉMATIQUES 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.
- 2 -
To Exposed Metal
Parts on Set
AC
1.5k Ω
voltmeter
(0.75V)
Earth Ground
À LA SÉCURITÉ!