SA-WCT770 - Sony Audio Service Manual (repair manual)

2014G33-1

© 

2014.07

•  SA-WCT770 is the active subwoofer in HT-CT770.
•  All of the units included in the HT-CT770 (SA-WCT770/

SA-CT770) are required to confi rming operation of SA-
WCT770. Check in advance that you have all of the units.

•  For the TEST MODE for this unit, refer to the service manual of HT-CT770.

POWER OUTPUT (reference)

120 W (per channel at 4 ohms, 100 Hz) (Except Chinese model)
75W (per channel at 4 ohms, 100 Hz) (Chinese model)

Speaker system

Subwoofer system, Bass reflex

Speaker

160 mm (6 3/8 in) cone type

Rated impedance

4 ohms

Power requirements

120 V AC, 60 Hz (US, Canadian and Mexican models)
220 V - 240 V AC, 50 Hz/60 Hz (AEP, UK, Australian, Chinese and Singapore models)
110 V - 240 V AC, 50 Hz/60 Hz (Saudi Arabia model)
120 V AC, 50 Hz/60 Hz (Taiwan model)

Power consumption

On: 30 W
Standby mode: 0.5 W or less

Dimensions (approx.) (w/h/d)

271 mm × 404 mm × 271 mm
(10 3/4 in × 16 in × 10 3/4 in)

Mass (approx.)

8.8 kg (17 Ib 10 1/2 oz)

Speaker system

Wireless Sound Specification version 2.0

Frequency band

2.4 GHz (2.4000 GHz - 2.4835 GHz)

Modulation method

Pi / 4 DQPSK

Design and specifications are subject to change without notice.

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.

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)

This system incorporates Dolby* Digital and the DTS** Digital Surround  
System.
* Manufactured under license from Dolby Laboratories. 

Dolby, and the double-D symbol are trademarks of Dolby 
Laboratories.

** Manufactured under license under U.S. Patent Nos: 5,956,674; 

5,974,380; 6,226,616; 6,487,535; 7,212,872; 7,333,929; 7,392,195;  
7,272,567 & other U.S. and worldwide patents issued & pending. 
DTS-HD, the Symbol, & DTS-HD and the Symbol together are  
registered trademarks of DTS, Inc.
Product includes software. © DTS, Inc. All Rights Reserved.

The BLUETOOTH® word mark and logos are registered trademarks owned  
by Bluetooth SIG, Inc. and any use of such marks by Sony Corporation is  
under license.

This system incorporates High-Definition Multimedia Interface (HDMI™) 
technology. 
The terms HDMI and HDMI High-Definition Multimedia Interface, and the 
HDMI Logo are trademarks or registered trademarks of HDMI Licensing 
LLC in the United States and other countries.

“BRAVIA” logo is a trademark of Sony Corporation.

“DSEE” is a trademark of Sony Corporation. 

“x.v.Color” and “x.v.Color” logo are trademarks of Sony Corporation. 

“PlayStation

®

” is a registered trademark of Sony Computer Entertainment  

Inc.

The N Mark is a trademark or registered trademark of NFC Forum, Inc. in 
the United States and in other countries.

Android and Google Play are trademarks of Google Inc.

"ClearAudio+" is a trademark of Sony Corporation.

Apple, the Apple logo, iPhone, iPod, and iPod touch are trademarks of 
Apple Inc., registered in the U.S. and other countries. App Store is a 
service mark of Apple Inc.

“Made for iPod,” and “Made for iPhone” mean that an electronic  
accessory has been designed to connect specifically to iPod or iPhone, 
respectively, and has been certified by the developer to meet Apple 
performance standards. Apple is not responsible for the operation of this 
device or its compliance with safety and regulatory standards. Please 
note that the use of this accessory with iPod or iPhone may affect 
wireless performance.

The compatible iPod/iPhone models are as follows. Update your iPod/
iPhone with the latest software before using with the system. 

BLUETOOTH technology works with:

iPhone
iPhone 5s/iPhone 5c/iPhone 5/iPhone 4s/iPhone 4/iPhone 3GS
iPod touch
iPod touch (5th generation)/iPod touch (4th generation)

Other trademarks and trade names are those of their respective owners.

0  OR  DOTTED  LINE  

0  ON  THE  SCHEMATIC  DIAGRAMS  AND  IN  

0  SUR  

 .............................................  

4

2-1. Disassembly 

Flow 

...........................................................   6

2-2.  Rear Panel Block ............................................................   6
2-3.  Top Panel Block ..............................................................   7
2-4.  SUB LED Board .............................................................   8
2-5. Sub 

AMP 

Block 

..............................................................   8

2-6.  Top Plate Block, Fuse (F900) .........................................   9
2-7. POWER 

Board 

................................................................   9

2-8.  Power Cord (AC1) ..........................................................   10
2-9.  RF Modulator (SWA12-4V RX) (RF1) ..........................   11
2-10.  Rear Plate Block .............................................................   11
2-11.  SUB MAIN Board ..........................................................   12
2-12.  Bottom Panel Block ........................................................   13
2-13.  Loudspeaker (16 cm) (SP1) ............................................   14

 ..........................................   15

4-1. Block 

Diagram 

................................................................  16

4-2.  Printed Wiring Board - SUB MAIN Board (Side A) - ....   18
4-3.  Printed Wiring Board - SUB MAIN Board (Side B) - ....   19
4-4.  Schematic Diagram - SUB MAIN Board (1/2) - ............   20
4-5.  Schematic Diagram - SUB MAIN Board (2/2) - ............   21
4-6.  Printed Wiring Board - POWER Board - ........................   22
4-7.  Schematic Diagram - POWER Board - ..........................   23
4-8. Printed 

Wiring 

Boards 

- SUB LED/SUB KEY Boards - .....................................   24

4-9.  Schematic Diagram - SUB LED/SUB KEY Boards - ....   24

5-1. Overall 

Section 

...............................................................  29

5-2. Sub 

AMP 

Section 

............................................................  30

5-3.  Subwoofer Cabinet Section ............................................   31

 ..............................   32

UNLEADED  SOLDER
Boards requiring use of unleaded solder are printed with the lead-
free mark (LF) indicating the solder contains no lead.
(Caution:  Some printed circuit boards may not come printed with 

the lead free mark due to their particular size)

Unleaded solder has the following characteristics.
•  Unleaded solder melts at a temperature about 40 °C higher 

than ordinary solder.

 

Ordinary soldering irons can be used but the iron tip has to be 
applied to the solder joint for a slightly longer time.

 

Soldering irons using a temperature regulator should be set to 
about 350 °C.
Caution: The printed pattern (copper foil) may peel away if 

the heated tip is applied for too long, so be careful!

• Strong 

viscosity

 

Unleaded solder is more viscous (sticky, less prone to fl ow) 
than ordinary solder so use caution not to let solder bridges 
occur such as on IC pins, etc.

• 

Usable with ordinary solder

 

It is best to use only unleaded solder but unleaded solder may 
also be added to ordinary solder.

ADVANCE  PREPARATION  WHEN  CONFIRMING  OP-
ERATION
All of the units included in the HT-CT770 (SA-WCT770/SA-
CT770) are required to confi rming operation of SA-WCT770. 
Check in advance that you have all of the units.

NOTE  OF  PERFORMING  THE  OPERATION  CHECK  IN  
THE  STATE  THAT  HEAT  SINK  WAS  REMOVED
When performing the operation check in the state that this unit was 
disassembled, it is possible to perform the operation check in the 
state that heat sink was removed. But don’t perform the operation 
check in the long time, and perform the operation check in the 
volume state as low as possible.

q Press the ÒÄÆ (on/standby) button to turn off the system. After the 

indicator disappears, disconnect the AC power cord (mains lead) 
then check that nothing is blocking the ventilation holes of the 
system.

NOTE  OF  REPLACING  THE  IC104  ON  THE  SUB  MAIN  
BOARD  AND  THE  COMPLETE  SUB  MAIN  BOARD
When IC104 on the SUB MAIN board and the complete SUB 
MAIN board are replaced, it is necessary to spread the compound 
between the SUB MAIN board and the heat sink.
Spread the compound (THERMAL COMPOUND (G747)) refer-
ring to the fi gure below.

CAPACITOR  ELECTRICAL  DISCHARGE  PROCESSING 
When checking the board, for the electric shock prevention, con-
nect the resistors to both ends of respective capacitor (C935 or 
C936) to discharge the capacitor (C935 or C936).

:/2 W