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
μ
F
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
