SONY STSA50ES
Manual de Servicio

TABLE OF CONTENTS 1. GENERAL ............................................................................ 3 2. DISASSEMBLY
2-1. Panel, Front Assembly ........................................................ 4 2-2. Display Board, Encoder Board, AC SW Board .................. 4 2-3. Panel Front ......................................................................... 4

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.

3. TEST MODE ........................................................................ 5 4. ELECTRICAL ADJUSTMENTS ................................... 7 5. DIAGRAMS
5-1. 5-2. 5-3. 5-4. 5-5. 5-6. 5-7. 5-8. Circuit Boards Location ................................................... 11 Printed Wiring Board � Display Section � ....................... 13 Schematic Diagram � Display Section � .......................... 15 Printed Wiring Board � Tuner Section � .......................... 17 Schematic Diagram � Tuner Section (1/2)� ..................... 19 Schematic Diagram � Tuner Section (2/2)� ..................... 21 IC Pin Function ................................................................ 23 IC Block Diagrams ........................................................... 24

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

2.

6. EXPLODED VIEW
6-1. Front Panel and Case Section ........................................... 25

3.

7. ELECTRICAL PARTS LIST ......................................... 26

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.

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.

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