SONY SAIF70
Service Manual

TABLE OF CONTENTS 1. SERVICING NOTE .......................................................... 3 2. ELECTRICAL ADJUSTMENTS ................................. 3 3. DIAGRAMS
3-1. Printed Wiring Board � Transmitter Section � .................. 5 3-2. Schematic Diagram � Transmitter Section � .................... 7 3-3. Printed Wiring Board � Receiver Section � ...................... 9 3-4. Schematic Diagram � Receiver Section � ....................... 11 3-5. IC Block Diagrams .............................................................. 13

SAFETY CHECK-OUT After correcting the original service problem, perform the following safety checks 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 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 0.5 mA (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 0.75 V, 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)

4. EXPLODED VIEWS
4-1. Speaker Section ................................................................... 14 4-2. Transmitter Section (EMT-70) ............................................ 15

5. ELECTRICAL PARTS LIST ........................................ 16

To Exposed Metal Parts on Set

0.15µF

1.5k�

AC voltmeter (0.75V)

Earth Ground

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

Notes on chip component replacement � Never reuse a disconnected chip component. � Notice that the minus side of a tantalum capacitor may be damaged by heat.

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 � LA S�CURIT�!! LES COMPOSANTS IDENTIFI�S PAR UNE MARQUE ! SUR LES DIAGRAMMES SCH�MATIQUES ET LA LISTE DES PI�CES SONT CRITIQUES POUR LA S�CURIT� DE FONCTIONNEMENT. NE REMPLACER CES COMPOSANTS QUE PAR DES PI�CES SONY DONT LES NUM�ROS SONT DONN�S DANS CE MANUEL OU DANS LES SUPPL�MENTS PUBLI�S PAR SONY.

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