Sony STR-DB925 Service Manual ▷ View online
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MICROFILM
AEP Model
UK Model
Australian Model
SPECIFICATIONS
SERVICE MANUAL
FM STEREO/FM-AM RECEIVER
STR-DB925
— Continued on next page —
Photo: BLACK
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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.
Notes on chip component replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be
• Notice that the minus side of a tantalum capacitor may be
damaged by heat.
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SECTION 1
SERVICING NOTE
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.
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.
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.
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.
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.
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.
• The MASTER VOLUME LED does not light up
• The MASTER VOLUME cannot be turned UP/DOWN using the remote controller.
1. SERVICING NOTE
.......................................................... 3
2. GENERAL
.......................................................................... 5
3. DIAGRAMS
3-1. Circuit Boards Location ........................................................ 6
3-2. Block Diagrams
3-2. Block Diagrams
• DSP Section ........................................................................ 7
• Input Section ....................................................................... 9
• Power Section ................................................................... 11
• Dolby Section ................................................................... 13
• 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
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
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
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
4-2. Front Panel Section ............................................................. 69
4-3. Chassis Section ................................................................... 70
5. ELECTRICAL PARTS LIST
........................................ 71
TABLE OF CONTENTS
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DSP SELF DIAGNOSIS FUNCTION
This unit is equipped with a DSP self-diagnosis function.
After completing self-diagnosis, the “DSP TEST MODE” can be set, where signals input from the external equipment will be
assigned to the designated channels as shown in the table below.
After completing self-diagnosis, the “DSP TEST MODE” can be set, where signals input from the external equipment will be
assigned to the designated channels as shown in the table below.
Table-1 Assignment of Signals in DSP TEST MODE
Procedure:
1. Connect external equipment such as CD and DVD players using the DIGITAL cable (optical or coaxial).
2. Rotate the FUNCTION knob, and switch to the FUNCTION connecting the external equipment.
3. Press the INPUT MODE button, and select the type of DIGITAL signal connected at 1.
1. Connect external equipment such as CD and DVD players using the DIGITAL cable (optical or coaxial).
2. Rotate the FUNCTION knob, and switch to the FUNCTION connecting the external equipment.
3. Press the INPUT MODE button, and select the type of DIGITAL signal connected at 1.
(“AUTO INPUT” is recommended for convenience.)
4. Press the 1/u button to turn OFF the power.
5. Press the 1/u button while pressing the SET UP and SOUND FIELD GENRE buttons to turn ON the power.
6. Perform DSP check in the following sequence to display the results. If no problems, “DSP NO ERROR” will be displayed on the
5. Press the 1/u button while pressing the SET UP and SOUND FIELD GENRE buttons to turn ON the power.
6. Perform DSP check in the following sequence to display the results. If no problems, “DSP NO ERROR” will be displayed on the
fluorescent indicator tube, and the reference signals of the 1 KHz internal oscillation will be output to FRONT, REAR, CENTER, and
WOOFER.
WOOFER.
Sequence :
1 DSP1 BOOT ERROR CHECK (DSP1:IC1301)
µ
2 DSP1 REPLAY ERROR CHECK
µ
3 DSP2 RAM ERROR CHECK (DSP2:IC1402 RAM:IC1402)
µ
4 DSP2 REPLAY ERROR CHECK
Refer to Table 2 if errors occur and perform the repairs.
Table-2 Display of Errors and Main Causes
7. Each time the
<
,
∧
,
∨
, or
>
button is pressed, the display changes between “DSP TEST MODE” and “DSP NO ERROR”.
When “DSP TEST MODE” is displayed, the signals input from the external equipment connected at 1. will be assigned to the outputs as
shown in Table 1.
When “DSP NO ERROR” is displayed, the reference signal of the internal oscillation will be output to the FRONT, REAR, CENTER, and
WOOFER channels.
(Each time the
shown in Table 1.
When “DSP NO ERROR” is displayed, the reference signal of the internal oscillation will be output to the FRONT, REAR, CENTER, and
WOOFER channels.
(Each time the
<
,
∧
,
∨
, or
>
button is pressed, self-diagnosis will be executed from
3 of step 6.
8. To end, press the 1/u button and turn OFF the power.
Note:
Do not touch other buttons except
Do not touch other buttons except
<
,
∧
,
∨
, or
>
during this mode with a specific purpose.
Messages are displayed in the same way as in normal operations.
Operations itself will not be normal here, therefore if other buttons or knobs are touched by accident and the message is changed, press
the 1/u button to turn OFF the power and exit the mode.
Operations itself will not be normal here, therefore if other buttons or knobs are touched by accident and the message is changed, press
the 1/u button to turn OFF the power and exit the mode.
Output To
FRONT L-ch + CENTER + REAR L-ch
FRONT R-ch + WOOFER + REAR R-ch
Possible Cause and Countermeasure
Faulty connection of IC1301, fault around the power supply of IC1301
Fault of peripheral circuit of Pin
@º of IC1301
Faulty connection with RAM (IC1402)
Faulty communication with microprocessor, fault of peripheral circuit of Pin
!£ of IC1401,
fault around power supply and clock of IC1401
Error Message
DSP1 BOOT ERROR
DSP1 REPLY ERROR
DSP2 RAM ERROR
DSP2 REPLY ERROR
Input Signal
FRONT L-ch
FRONT R-ch