SA-WCT770 - 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-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