HCD-GTR33, HCD-GTR55, HCD-GTR77, MHC-GTR33, MHC-GTR55, MHC-GTR77 - Sony Audio Service Manual (repair manual). Page 2

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HCD-GTR33/GTR55/GTR77
2
TABLE  OF  CONTENTS
NOTES  ON  CHIP  COMPONENT  REPLACEMENT
•  Never reuse a disconnected chip component.
•  Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
FLEXIBLE  CIRCUIT  BOARD  REPAIRING
•  Keep the temperature of soldering iron around 270 °C during repairing.
•  Do not touch the soldering iron on the same conductor of the circuit 
board (within 3 times).
•  Be careful not to apply force on the conductor when soldering or unsol-
dering.
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.
CAUTION
Use of controls or adjustments or performance of procedures 
other than those specifi ed herein may result in hazardous radia-
tion exposure.
SAFETY  CHECK-OUT
After correcting the original service problem, perform the following safe-
ty 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 instru-
ments.
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.
1. SERVICING 
NOTES
 ................................................  
3
2. DISASSEMBLY
2-1. Disassembly 
Flow 
...........................................................   5
2-2. Case 
(Side-L/R) 
..............................................................   5
2-3. Top 
Case..........................................................................   6
2-4.  Tape Mechanism Deck ....................................................   6
2-5.  Front Panel Block, HUB Board, 
 DMB19 
Board 
.................................................................  
7
2-6.  DC Fan (M101), Back Panel ...........................................   7
2-7. MAIN 
Board 
...................................................................   8
2-8. POWER 
Board 
................................................................   8
2-9. Chassis 
Section 
...............................................................   9
2-10.  CD Mechanism Block (CDM88B-DVBU101) ...............   9
2-11.  Optical Pick-up Block (KHM-313CAB) ........................   10
2-12. Belt (DLM3A) ................................................................   10
3. 
TEST  MODE
 .............................................................   11
4. MECHANICAL 
ADJUSTMENTS
 ........................   13
5. 
ELECTRICAL  CHECK
 ..........................................   14
6. DIAGRAMS
6-1.  Block Diagram - RF SERVO, USB Section - .................   15
6-2.  Block Diagram - MAIN Section - ...................................   16
6-3.  Block Diagram - AMP Section - .....................................   17
6-4. Block 
Diagram 
- PANEL, POWER SUPPLY Section - ...........................   18
6-5.  Printed Wiring Board - DMB19 Board - ........................   20
6-6.  Schematic Diagram - DMB19 Board (1/3) - ..................   21
6-7.  Schematic Diagram - DMB19 Board (2/3) - ..................   22
6-8.  Schematic Diagram - DMB19 Board (3/3) - ..................   23
6-9.  Printed Wiring Board - MAIN Board - ...........................   24
6-10.  Schematic Diagram - MAIN Board (1/3) - .....................   25
6-11.  Schematic Diagram - MAIN Board (2/3) - .....................   26
6-12.  Schematic Diagram - MAIN Board (3/3) - .....................   27
6-13.  Printed Wiring Board - HUB Board - .............................   28
6-14.  Schematic Diagram - HUB Board - ................................   29
6-15.  Printed Wiring Board - POWER Board - ........................   30
6-16.  Schematic Diagram - POWER Board - ..........................   31
6-17.  Printed Wiring Board - DISPLAY Board - .....................   32
6-18.  Schematic Diagram - DISPLAY Board - ........................   33
6-19. Printed Wiring Board 
- MIC,  USB  AND  VOLUME  Board - ........................   34
6-20. Schematic Diagram 
- MIC,  USB  AND  VOLUME  Board - ........................   35
6-21.  Printed Wiring Board - TC Board - .................................   36
6-22.  Schematic Diagram - TC Board - ...................................   36
6-23.  Printed Wiring Board - TRANS Board - .........................   37
6-24.  Schematic Diagram - TRANS Board - ...........................   38
7. 
EXPLODED  VIEWS
7-1. Case 
Section 
....................................................................  49
7-2.  Top Panel Section ...........................................................   50
7-3.  Loading Panel Section, HUB Board Section, DMB19 
Board Section ..................................................................   51
7-4.  DISPLAY  Board Section ...............................................   52
7-5.  Front  Panel Section ........................................................   53
7-6.  Back  Panel Section ........................................................   54
7-7.  MAIN  Board Section .....................................................   55
7-8.  Chassis  Section ..............................................................   56
7-9.  CD  Mechanism Section 
(CDM88B-DVBU101) ...................................................   57
8. 
ELECTRICAL  PARTS  LIST
 ...............................   58
This appliance is classified as a CLASS 1 
LASER product. This marking is located on 
the rear exterior.
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