HT-ST7 - Sony Audio Service Manual (repair manual). Page 4

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-ST7 (SA-ST7/SA-WST7/EZW-
RT50) are required to confi rming operation of SA-ST7. 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.

NOTE  OF  REPLACING  THE  IC3506  ON  THE  MAIN  
BOARD
IC3506 on the MAIN board cannot exchange with single. When 
this part is damaged, exchange the complete mounted board.

NOTE  OF  REPLACING  THE  IC3001, IC3003, IC3005  
AND  IC3007  ON  THE  AMP  BOARD  AND  THE  COM-
PLETE  AMP  BOARD
When IC3001, IC3003, IC3005 and IC3007 on the AMP board and 
the complete AMP board are replaced, it is necessary to spread the 
compound between the AMP board and the heat sink.
Spread the compound referring 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 (C519) to 
discharge the capacitor (C519).

:/2 W

ABOUT  THE  PAIRING  METHOD
When the following replacing repair is performed, the pairing of 
the Bar speaker (SA-ST7) and Subwoofer (SA-WST7) is cut.

•   Replacing of complete MAIN board
•   Replacing of IC1002 on the MAIN board

Return the Bar speaker (SA-ST7) and Subwoofer (SA-WST7) to 
the customer after performing the pairing according to the follow-
ing procedure.

Preparation:
Insert the wireless transceivers (EZW-RT50) into the Bar speaker 
(SA-ST7) and Subwoofer (SA-WST7).

1  Connect the AC power cords (mains leads).  
2 Press 

the 

 button on the Bar Speaker.

3 Confirm 

the 

 indicator of the subwoofer is lit 

in green. If not, the wireless transmission is not 
activated.

 indicator is off:

– Check that the AC power cord (mains lead) of the subwoofer is connected

securely.

– Turn the subwoofer on by pressing the 

 button on the subwoofer.

 indicator flashes in green quickly:

First press the 

 button on the subwoofer, then insert the wieless transceiver 

into the subwoofer correctly, and press the 

 button on the subwoofer again.

 indicator flashes in red: 

If the

If the

If the

Make sure the AC power cord (mains lead) of the subwoofer is connected.
Make sure the wireless transceivers are inserted correctly.

Press the

 button to turn off the subwoofer, and check that nothing is  

blocking the ventilation holes of the subwoofer.