Table Of Contents; Servicing Note - Sony STR-DB925 Service Manual

1. SERVICING NOTE
.......................................................... 3
2. GENERAL
.......................................................................... 5
3. DIAGRAMS
3-1. Circuit Boards Location ........................................................ 6
3-2. Block Diagrams
• DSP Section ........................................................................ 7
• Input Section ....................................................................... 9
• Power Section ................................................................... 11
• Dolby Section ................................................................... 13
3-3. Schematic Diagram - Input Section - ................................ 17
3-4. Printed Wiring Board - Input Section - .............................. 19
3-5. Schematic Diagram - Power AMP Section - ..................... 21
3-6. Printed Wiring Board - Power AMP Section - ................... 23
3-7. Schematic Diagram - Trans Section - ............................... 25
3-8. Printed Wiring Board - Trans Section - ............................. 27
3-9. Schematic Diagram - Rear AMP Section - ........................ 29
3-10. Printed Wiring Board - Rear AMP Section - .................. 31
3-11. Schematic Diagram - Display Section - ......................... 33
FACTORY SET
Mode which sets the preset settings of the unit to that at shipment.
Procedure:
With the power off, press the 1/u button while pressing the SET UP and SOUND FIELD ON/OFF buttons to turn ON the power.
"FACTORY SET" will be displayed and FACTORY PRESET will be executed.
As the "DEMO MODE" will automatically be set about 1 minute later, press the 1/u button to turn OFF the power.
INITIALIZATION
This mode erases all the preset settings of the unit.
Use this mode when returning the unit to custimer.
Procedure:
With the power off, press the 1/u button while pressing the DISPLAY and SOUND FIELD ON/OFF buttons to turn ON the power.
As the "DEMO MODE" will automatically be set about 1 minute later, press the 1/u button to turn OFF the power.
FLUORESCENT INDICATOR TUBE AND LED LIGHTING CHECK
Mode which lights up the whole fluorescent indicator tube or partially.
Procedure:
With the power off, press the 1/u button while pressing the SET UP and SOUND FIELD MODE buttons to turn ON the power. The whole
fluorescent display tube will light up.
As the "DEMO MODE" will automatically be set about 1 minute later, press the 1/u button to turn OFF the power.
DEMO MODE (NOT USED IN SERVICE)
Mode for demonstration
Procedure:
With the power off, press the 1/u button while pressing the CURSOR button to turn ON the power.
To end, press the 1/u button to turn OFF the power.
PRECAUTIONS ON REMOVING THE FRONT PANEL
When the front panel is removed, the front panel board and VOLUME board cannot be connected, thus causing the following problems.
• The MASTER VOLUME LED does not light up
• The MASTER VOLUME cannot be turned UP/DOWN using the remote controller.

TABLE OF CONTENTS

3-12. Printed Wiring Board - Display Section - ....................... 35
3-13. Schematic Diagram - Panel Section - ............................. 37
3-14. Printed Wiring Board - Panel Section - ........................... 39
3-15. Schematic Diagram - Back Panel Section - .................... 41
3-16. Printed Wiring Board - Back Panel Section - .................. 43
3-17. Schematic Diagram - Volume Section - .......................... 45
3-18. Printed Wiring Board - Volume Section - ....................... 47
3-19. Schematic Diagram - D In/Out Section - ........................ 49
3-20. Printed Wiring Board - D In/Out Section - ..................... 50
3-21. Schematic Diagram - Digital (1/2) Section - .................. 51
3-22. Schematic Diagram - Digital (2/2) Section - .................. 53
3-23. Printed Wiring Board - Digital Section - ........................ 55
3-24. IC Block Diagrams ........................................................... 57
3-25. IC Pin Functions ............................................................... 60
4. EXPLODED VIEWS
4-1. Case and Back Panel Section .............................................. 68
4-2. Front Panel Section ............................................................. 69
4-3. Chassis Section ................................................................... 70
5. ELECTRICAL PARTS LIST
SECTION 1

SERVICING NOTE

- 3 -
........................................ 71