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MICROFILM
AEP Model
UK Model
SPECIFICATIONS
SERVICE MANUAL
FM STEREO/FM-AM RECEIVER
STR-DB725/DB825
-- Continued on next page --
Photo: STR-DB825


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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
damaged by heat.
TABLE OF CONTENTS
1. SERVICING NOTE .......................................................... 3
2. GENERAL .......................................................................... 4
3. DIAGRAMS
3-1. Circuit Boards Location ........................................................ 5
3-2. Block Diagrams
· Main Section ....................................................................... 7
· Power Section ..................................................................... 9
3-3. Schematic Diagram ­ Video Input Section ­ ...................... 13
3-4. Printed Wiring Board ­ Video Input Section ­ ................... 15
3-5. Schematic Diagram ­ Input Section ­ ................................ 17
3-6. Printed Wiring Board ­ Input Section ­ .............................. 19
3-7. Schematic Diagram ­ S-Video Section ­ ............................ 21
3-8. Printed Wiring Board ­ S-Video Section ­ ......................... 23
3-9. Schematic Diagram ­ Speaker Section ­ ............................ 25
3-10. Printed Wiring Board ­ Speaker Section ­ ...................... 27
3-11. Printed Wiring Board ­ Display Section ­ ....................... 29
3-12. Schematic Diagram ­ Display Section ­ ......................... 31
3-13. Schematic Diagram ­ Front Panel Section ­ ................... 33
3-14. Printed Wiring Board ­ Front Panel Section ­ ................. 35
3-15. Schematic Diagram ­ Power AMP Section ­ .................. 37
3-16. Printed Wiring Board ­ Power AMP Section ­ ................ 39
3-17. Schematic Diagram ­ Trans Section ­ ............................ 41
3-18. Printed Wiring Board ­ Trans Section ­ ........................... 42
3-19. IC Block Diagrams ........................................................... 43
3-20. IC Pin Functions ............................................................... 46
4. EXPLODED VIEWS
4-1. Case and Back Panel Section .............................................. 48
4-2. Front Panel Section ............................................................. 49
4-3. Chassis Section ................................................................... 50
5. ELECTRICAL PARTS LIST ........................................ 51
Parts No.
PARTS No.
MODEL
MODEL IDENTIFICATION
-- BACK PANEL --
4-900-493-0
4-900-493-1
DB725
DB825


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SECTION 1
SERVICING NOTE
FACTORY SET
Mode which sets the preset settings of the unit to that at shipment.
Procedure:
While pressing the < button and BASS BOOST button together, press the 1/u button to turn on the power.
"FACTORY" will be displayed and factory settings executed.
INITIALIZATION
Mode which erases all the preset settings of the unit.
Use this mode when returning the unit to the customer.
Procedure:
While pressing the MEMORY button and MUTING button together, press the 1/u button to turn on the power.
"ALL CLEAR" will be displayed and initialization executed.
FLUORESCENT INDICATOR TUBE AND LED LIGHTING CHECK
Mode which lights up the whole fluorescent indicator tube or partially.
Procedure:
While pressing the
button and BASS BOOST button together, press the 1/u button to turn on the power.
The whole fluorescent display tube lights up.
The fluorescent display tube and LED light up in the following sequence each time the FUNCTION knob is rotated.
KEY CHECK
Mode for checking key input.
Procedure:
Turn on the power by pressing the 1/u button while pressing the
button and the BASS BOOST button. "REST 25 KEY" is displayed.
The count decreases each time the button is pressed.
Buttons counted once will not be couned again.
"REST 00 KEY" is displayed when all the buttons are pressed.
The fluorescent display tube: All light up
LED: VIDEO 1 , VIDEO 3 , TAPE/MD ,
5.1/DVD INPUT , MASTER VOLUME
and SURROUND light
Turn the FUNCTION knob
Turn the FUNCTION knob
Turn the FUNCTION knob
Turn the FUNCTION knob
The fluorescent display tube: Light up partially (1)
LED: TV/LED , CD , PHONO ,
TONE , BASS/TREBLE and
MASTER VOLUME light
The fluorescent display tube: Light up partially (2)
LED: VIDEO 2 , TUNER , BASS BOOST ,
INDEX , MASTER VOLUME and
MUTING light
The fluorescent display tube: All lights out
LED: All lights out


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Front Panel Descriptions
SECTION 2
GENERAL
LOCATION OF PARTS AND CONTROLS
1
1/u (power) switch
2
DISPLAY button
3
FM/AM button
4
VIDEO 1 indicator
5
VIDEO 2 indicator
6
VIDEO 3 indicator
7
TV/LD indicator
8
TAPE/MD indicator
9
Display window
10 CD indicator
11 SURROUND indicator
12 TUNER indicator
13 PHONO indicator
14 5.1/DVD INPUT indicator
TONE indicator
BASS BOOST indicator
15 MASTER VOLUME knob
16 MUTING button and indicator
17 FUNCTION knob
18 MODE switch
19 BALANCE knob
20 SOUND FIELD ON/OFF button
21 SOUND FIELD MODE button
22 SOUND FIELD GENRE button
23 BASS BOOST button
24 TONE ON/OFF button
25 5.1/DVD INPUT button
26 BASS/TREBLE indicator
27 INDEX indicator
28 SET UP button
29 Digital Processing Controls
30 CURSOR MODE button
31 RDS EON button
32 RDS PTY button
33 VIDEO 3 INPUT AUDIO R connecot
34 VIDEO 3 INPUT AUDIO L connecot
35 VIDEO 3 INPUT VIDEO connecot
36 VIDEO 3 INPUT S-VIDEO connecot
37 TUNING + button
38 TUNING ­ button
39 FM MODE button
40 MEMORY button
41 PRESET TUNING + button
42 PRESET TUNING ­ button
43 SHIFT button
44 PHONES jack
45 SPEAKERS selector switch
78
2 3
46
5
1
10 11
13 14
15
12
9
45
26
29
17
18
19
21
22
20
27
28
30
33
34
35
36
23
24
25
31
32
37
38
39
40
41
42
16
43
44


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SECTION 3
DIAGRAMS
3-1. CIRCUIT BOARDS LOCATION
SURR board
S VIDEO board
STANDBY (2) board
DISPLAY board
AMP board
INPUT board
SP board
CONNECTOR board
H.P board
STANDBY board
BALANCE board
VIDEO board
FUNCTION board
SW board
VIDEO (3) board
SP SWITCH
board
VOLUME board
REAR AMP board