HCD-BX20I, HCD-BX50BTI - Sony Audio Service Manual (repair manual). Page 3

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HCD-BX20i/BX50BTi
3
1. 
SERVICING  NOTES
  .............................................   4
2. GENERAL
  ..................................................................   6
3. DISASSEMBLY
3-1. Disassembly 
Flow 
...........................................................  10
3-2.  Panel (Side L/R) ..............................................................   11
3-3.  Top Panel Block ..............................................................   11
3-4.  TOP KEY Board, IP Board, Panel Top (IP) ....................   12
3-5.  Front Panel Block ...........................................................   12
3-6.  Rear Panel Block ............................................................   13
3-7. Panel 
(Rear) 
....................................................................  13
3-8.  AMP Board Block ...........................................................   14
3-9.  POWER Board Block .....................................................   14
3-10. MAIN Board ...................................................................   15
3-11.  Loading Mechanism Block .............................................   15
3-12. Base Unit .........................................................................   16
3-13. Belt ..................................................................................   16
3-14.  OP Base Assy (KSM-213D) ...........................................   17
4. 
TEST  MODE 
 ............................................................   18
5. 
ELECTRICAL  CHECKS 
 ......................................   20
6. DIAGRAMS
6-1.  Block Diagram - CD SERVO Section - ..........................   21
6-2. Block 
Diagram 
 
- iPod, TUNER, BLUETOOTH Section - ......................   22
6-3.  Block Diagram - MAIN Section - ...................................   23
6-4. Block 
Diagram 
 
- PANEL, POWER SUPPLY Section - ...........................   24
6-5.  Printed Wiring Boards - CD Section - ............................   26
6-6.  Schematic Diagram - CD Board - ...................................   27
6-7. Printed 
Wiring 
Boards 
 
- BLUETOOTH Section (BX50BTi) - ............................   28
6-8. Schematic 
Diagram 
 
- BLUETOOTH Section (BX50BTi) - ............................   29
6-9.  Printed Wiring Board - IP Board - ..................................   30
6-10.  Schematic Diagram - IP Board - .....................................   31
6-11.  Printed Wiring Boards - MAIN Section - .......................   32
6-12.  Schematic Diagram - MAIN Section (1/3) - ...................   33
6-13.  Schematic Diagram - MAIN Section (2/3) - ...................   34
6-14.  Schematic Diagram - MAIN Section (3/3) - ...................   35
6-15. Printed Wiring Boards 
 
- HEADPHONE/AMP Section - .....................................   36
6-16.  Schematic Diagram - HEADPHONE/AMP Section - ....   37
6-17.  Printed Wiring Boards - PANEL Section - .....................   38
6-18.  Schematic Diagram - PANEL Section - ..........................   39
6-19.  Printed Wiring Board - POWER Board - ........................   40
6-20.  Schematic Diagram - POWER Board - ..........................   41
7. 
EXPLODED  VIEWS
7-1. Panel 
Section 
...................................................................  50
7-2.  Top Panel Section ...........................................................   51
7-3.  Front Panel Section .........................................................   52
7-4.  MAIN Board Section ......................................................   53
7-5.  POWER Board Section ...................................................   54
7-6.  Loading Mechanism Section ..........................................   55
7-7.  Base Unit Section (BU-K6BD90-WOD)  .......................   56
8. 
ELECTRICAL  PARTS  LIST
  ..............................   57
TABLE  OF  CONTENTS
SAFETY  CHECK-OUT
After correcting the original service problem, perform the follow-
ing 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)
Fig. A.  Using an AC voltmeter to check AC leakage.
1.5 k
Ω
0.15 
μF
AC
voltmeter
(0.75 V)
To Exposed Metal
Parts on Set
Earth Ground
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