SONY STR-DB925 AV Receivers Owner’s Manual
- June 10, 2024
- Sony
Table of Contents
STR-DB925 AV Receivers
Product Information: STR-DB925 FM Stereo/FM-AM Receiver
The STR-DB925 is a high-quality FM Stereo/FM-AM Receiver made by Sony. It features a DSP self-diagnosis function, fluorescent indicator tube, LED lighting, and several modes such as FACTORY SET, INITIALIZATION, FLUORESCENT INDICATOR TUBE AND LED LIGHTING CHECK, and DEMO MODE.
Specifications
- Model: STR-DB925
- Color: Black
- FM Stereo/FM-AM Receiver
- Safety-related component warning
- Table of Contents:
- Servicing Note
- General
- Diagrams
- Exploded Views
- Electrical Parts List
Product Usage Instructions:
To turn on the STR-DB925, press the 1/u button. To turn off the receiver, press the same button again. The FUNCTION knob can be used to switch to different input sources such as CD and DVD players.
The receiver features several modes, such as FACTORY SET, INITIALIZATION, FLUORESCENT INDICATOR TUBE AND LED LIGHTING CHECK, and DEMO MODE. Follow the specific procedures mentioned in the user manual to enter each mode.
The DSP SELF DIAGNOSIS FUNCTION allows you to assign signals from external equipment to designated channels. Connect external equipment such as CD and DVD players using the DIGITAL cable (optical or coaxial), and then rotate the FUNCTION knob to switch to the FUNCTION connecting the external equipment. Refer to Table-1 for signal assignments in DSP TEST MODE.
It is important to note the safety-related component warning mentioned in the user manual. Replace critical components identified by mark ! or dotted line with mark ! only with Sony parts whose part numbers appear as shown in the manual or in supplements published by Sony.
This receiver incorporates the Dolby Pro Logic Surround system and the DTS** Digital Surround System.
Manufactured under license from Dolby Laboratories Licensing Corporation.
DOLBY, the double-D symbol C3, “PRO LOGIC and Dolby Digital (AC-3) are
trademarks of Dolby Laboratories Licensing Corporation.
*Manufactured under license from Digital Theater Systems, Inc.. Us Pat. No. 5,451,942 and other worldwide patents issues and pending “DTS” and “DTS Digital Surround” are trademarks of Digital Theater Systems, Inc. © 1996 Digital Theater Systems, Inc. Al rights reserved.
PRODUCT SPECIFICATIONS
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.
SERVICING NOTE
FACTORY SET
Mode which sets the preset settings of the unit to that at shipment.
Procedure:
With the power off, press the 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
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 customer.
Procedure:
With the power off, press the 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
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 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
button to turn OFF the power.
DEMO MODE (NOT USED IN SERVICE)
Mode for demonstration
Procedure:
With the power off, press the button while pressing the CURSOR button to turn
ON the power.
To end, press the 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.
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.
Table-1 Assignment of Signals in DSP TEST MODE
| Input Signal | Output To |
|---|---|
| FRONT L-ch | FRONT L-ch + CENTER + REAR L-ch |
| FRONT R-ch | FRONT R-ch + WOOFER + REAR R-ch |
Procedure:
-
Connect external equipment such as CD and DVD players using the DIGITAL cable (optical or coaxial).
-
Rotate the FUNCTION knob, and switch to the FUNCTION connecting the external equipment.
-
Press the INPUT MODE button, and select the type of DIGITAL signal connected at 1.
(“AUTO INPUT” is recommended for convenience.) -
Press the button to turn OFF the power.
-
Press the button while pressing the SET UP and SOUND FIELD GENRE buttons to turn ON the power.
-
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.
Sequence :
-
DSP1 BOOT ERROR CHECK (DSP1:IC1301)
-
DSP1 REPLAY ERROR CHECK
-
DSP2 RAM ERROR CHECK (DSP2:IC1402 RAM:IC1402)
-
DSP2 REPLAY ERROR CHECK
Refer to Table 2 if errors occur and perform the repairs.Error Message| Possible Cause and Countermeasure
---|---
DSP1 BOOT ERROR| Faulty connection of IC1301, fault around the power supply of IC1301
DSP1 REPLY ERROR| Fault of peripheral circuit of Pin @º of IC1301
DSP2 RAM ERROR| Faulty connection with RAM (IC1402)
DSP2 REPLY ERROR| Faulty communication with microprocessor, fault of peripheral circuit of Pin !£ of IC1401, fault around power supply and clock of IC1401 -
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 < , ∨ ,∧ or > button is pressed, self-diagnosis will be executed from 3 of step 6. -
To end, press the button and turn OFF the power.
Note:
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 button to turn
OFF the power and exit the mode.
GENERAL
Front Panel Descriptions
LOCATION OF PARTS AND CONTROLS
- (power) switch
- VIDEO 1 indicator
- VIDEO 2 indicator
- VIDEO 3 indicator
- DVD indicator
- TV/LD indicator
- MULTI CHANNEL DECODING indicator
- TAPE indicator
- MD/DAT indicator
- CD indicator
- TUNER indicator
- PHONO indicator
- MASTER VOLUME knob and indicator
- MUTING indicator
- MUTING button
- FUNCTION knob
- MODE switch
- SOUND FIELD indicator
- EQ indicator
- BASS BOOST button
- BALANCE knob
- SOUND FIELD ON/OFF button
- SOUND FIELD MODE button
- SOUND FIELD GENRE button
- INPUT MODE button
- 5.1 INPUT button
- EQ ON/OFF button
- SET UP button
- SURROUND indicator
- EQUALIZER indicator
- INDEX indicator
- <, ∧, ∨, > buttons
- SET UP button
- RDS EON button
- RDS PTY button
- TUNING + button
- TUNING – button
- VIDEO 3INPUT jacks
- FM MODE button
- MEMORY button
- DISPLAY button
- PRESET TUNING + button
- PRESET TUNING – button
- FM/AM button
- SHIFT button
- PHONES jack
- SPEAKERS knob
DIAGRAMS
CIRCUIT BOARDS LOCATION
EXPLODED VIEWS
NOTE:
-
Items marked “*” are not stocked since they are seldom required for routine service. Some delay should be anticipated when ordering these items.
-
Color Indication of Appearance Parts Example: KNOB, BALANCE (WHITE)
↑
Cabinet’s color -
The mechanical parts with no reference number in the exploded views are not supplied.
-
Hardware (# mark) list and accessories and packing materials are given in the last of this parts list.
The components identified by mark ! or dotted line with mark are critical for safety. Replace only with part number specified.
CASE AND BACK PANEL SECTION
FRONT PANEL SECTION 
CHASSIS SECTION
The components identified by mark ! or dotted line with mark ! are critical for safety. Replace only with part number specified.