Sony STR-K900 Service Manual - Page 3

STR-K880/K900 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 0.5 mA (500 microamperes.). 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 2 V AC range are suitable. (See Fig. A) To Exposed Metal Parts on Set 0.15 µF 1.5 kΩ AC voltmeter (0.75 V) Earth Ground Fig. A. Using an AC voltmeter to check AC leakage. SAFETY-RELATED COMPONENT WARNING!! COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE WITH MARK 0 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 À LA SÉCURITÉ! LES COMPOSANTS IDENTIFIÉS PAR UNE MARQUE 0 SUR LES DIAGRAMMES SCHÉMATIQUES ET LA LISTE DES PIÈCES SONT CRITIQUES POUR LA SÉCURITÉ DE FONCTIONNEMENT. NE REMPLACER CES COM- POSANTS QUE PAR DES PIÈCES SONY DONT LES NUMÉROS SONT DONNÉS DANS CE MANUEL OU DANS LES SUPPLÉMENTS PUBLIÉS PAR SONY. TABLE OF CONTENTS 1. GENERAL 4 2. TEST MODE 12 3. DIAGRAMS 14 3-1. Block Diagram - MAIN Section 16 3-2. Block Diagram - DISPLAY/POWER Section 17 3-3. Printed Wiring Board - DIGITAL Board (Side A) - ....... 18 3-4. Printed Wiring Board - DIGITAL Board (Side B) - ....... 19 3-5. Schematic Diagram - DIGITAL Board (1/5 20 3-6. Schematic Diagram - DIGITAL Board (2/5 21 3-7. Schematic Diagram - DIGITAL Board (3/5 22 3-8. Schematic Diagram - DIGITAL Board (4/5 23 3-9. Schematic Diagram - DIGITAL Board (5/5 24 3-10. Printed Wiring Board - MAIN Board 25 3-11. Schematic Diagram - MAIN Board (1/3 26 3-12. Schematic Diagram - MAIN Board (2/3 27 3-13. Schematic Diagram - MAIN Board (3/3 28 3-14. Printed Wiring Boards - DISPLAY Board, POWER Board 29 3-15. Schematic Diagrams - DISPLAY Board, POWER Board 30 3-16. Printed Wiring Boards - STANDBY Board, AC SELECT Board 31 3-17. Printed Wiring Board - SPEAKER Board 32 3-18. Schematic Diagram - SPEAKER Board, STANDBY Board, AC SELECT Board 33 3-19. Printed Wiring Board - SPEAKER B Board 34 3-20. Printed Wiring Boards - ADCC Board, VIDEO 3 Board 35 3-21. Schematic Diagrams - SPEAKER B Board, ADCC Board, VIDEO 3 Board 36 3-22. Printed Wiring Boards - VIDEO Board, HEADPHONE Board 37 3-23. Schematic Diagram - VIDEO Board, HEADPHONE Board 38 3-24. Printed Wiring Board - HDMI Board 39 3-25. Schematic Diagram - HDMI Board 40 4. EXPLODED VIEWS 4-1. Front Panel Section 49 4-2. Chassis Section-1 50 4-3. Chassis Section-2 51 5. ELECTRICAL PARTS LIST 52 About area codes The area code of the receiver you purchased is shown on the lower right portion of the rear panel (see the illustration below). CENTER + - SURROUND BACK L L + - + - R SURROUND SPEAKERS R FRONT A RL RL FRONT B SPEAKERS Area code Any differences in operation, according to the area code, are clearly indicated in the text, for example, "Models of area code AA only". 3