STR-DH550, STR-DH750 - Sony Audio Service Manual (repair manual). Page 3

Read Sony STR-DH550 / STR-DH750 Service Manual online

STR-DH550/DH750
3
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)
1.5 k
Ω
0.15 
μF
AC 
voltmeter 
(0.75 V) 
To Exposed Metal 
Parts on Set 
Earth Ground
Fig. A.  Using an AC voltmeter to check AC leakage.
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 
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  FONC-
TIONNEMENT.  NE  REMPLACER  CES  COMPOSANTS  QUE  
PAR  DES  PIÈCES  SONY  DONT  LES  NUMÉROS  SONT  DON-
NÉS  DANS  CE  MANUEL  OU  DANS  LES  SUPPLÉMENTS  
PUBLIÉS  PAR  SONY.
1. 
SERVICING  NOTES 
 .............................................  
4
2. DISASSEMBLY
2-1. Case 
(Entry) 
....................................................................   5
2-2.  Front Panel Section .........................................................   6
2-3.  Back Panel Section .........................................................   7
2-4.  MAIN Board Section ......................................................   8
2-5. MAIN 
Board 
...................................................................   9
3. 
TEST  MODE 
 ............................................................   10
4. 
FM  TUNER  CHECK 
 .............................................   13
5. DIAGRAMS
5-1.  Block Diagram - ANALOG AUDIO Section - ...............   15
5-2.  Block Diagram - DIGITAL Section - .............................   16
5-3.  Block Diagram - AMP Section - .....................................   17
5-4.  Block Diagram - ANALOG VIDEO/USB Section - ......   18
5-5.  Block Diagram - DIGITAL VIDEO Section - ................   19
5-6.  Block Diagram - DISPLAY/POWER Section - ..............   20
5-7. Printed 
Wiring 
Board 
- MAIN Board (Component Side) - ................................   22
5-8. Printed 
Wiring 
Board 
- MAIN Board (Conductor Side) - ..................................   23
5-9.  Schematic Diagram - MAIN Board (1/7) - .....................   24
5-10.  Schematic Diagram - MAIN Board (2/7) - .....................   25
5-11.  Schematic Diagram - MAIN Board (3/7) - .....................   26
5-12.  Schematic Diagram - MAIN Board (4/7) - .....................   27
5-13.  Schematic Diagram - MAIN Board (5/7) - .....................   28
5-14.  Schematic Diagram - MAIN Board (6/7) - .....................   29
5-15.  Schematic Diagram - MAIN Board (7/7) - .....................   30
5-16. Printed Wiring Board 
- HDMI Board (Component Side) - ................................   31
5-17. Printed Wiring Board 
- HDMI Board (Conductor Side) - ..................................   32
5-18.  Schematic Diagram - HDMI Board - ..............................   33
5-19. Printed Wiring Board 
- STANDBY DCDC Board (Component Side) - ............   34
5-20. Printed Wiring Board 
- STANDBY DCDC Board (Conductor Side) - ..............   35
5-21.  Schematic Diagram - STANDBY DCDC Board - ..........   36
5-22.  Printed Wiring Board - PANEL Section - .......................   37
5-23.  Schematic Diagram - PANEL Section - ..........................   38
5-24.  Printed Wiring Board - FRONT JACK Board - ..............   39
5-25.  Schematic Diagram - FRONT JACK Board - ................   39
5-26.  Printed Wiring Board - TUNER1 Board - ......................   39
5-27.  Schematic Diagram - TUNER1 Board - .........................   40
5-28.  Printed Wiring Board - POWER KEY Board -...............   41
5-29.  Schematic Diagram - POWER KEY Board - .................   41
5-30.  Printed Wiring Board - HEADPHONE Board - .............   42
5-31.  Schematic Diagram - HEADPHONE Board - ................   42
6. 
EXPLODED  VIEWS
6-1.  Case (Entry) Section .......................................................   57
6-2.  Front Panel Section .........................................................   58
6-3.  Back Panel Section .........................................................   59
6-4. Chassis 
Section 
...............................................................  60
7. 
ELECTRICAL  PARTS  LIST 
 ..............................   61
TABLE  OF  CONTENTS
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