SA-WCT780 - Sony Audio Service Manual (repair manual). Page 17

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SA-WCT780
SA-WCT780
17
17
3.  The sound is not outputted
There is no problem of contact between 
connector (CN107) on the SW-MAIN 
board and flexible flat cable (FFC1).
The waveform of the following is inputted.
SW-MAIN board: IC105 pin 29 (LRCK)
 
IC105 pin 30 (BCK)
 
IC105 pin 31 (DATA)
 
IC105 pin 36 (XFSIIN)
Yes
Yes
The sound is outputted from the 
connector (CN109) on the SW-MAIN 
board.
Yes
Replace the flexible flat cable 
(FFC1).
No
No
Replace the RF modulator 
(RF1).
Check the LC circuit of 
amplifier ouput.
(L101, L102, C172, C174)
Yes
No
The sound is not outputted.
The waveform is outputted from the 
IC104 pin 31 (OUT_C), 28 (OUT_D) on 
the SW-MAIN board.
Yes
Yes
The waveform is outputted 
from the IC105 pin 6 (OUTR1), 
4 (OUTR2) on the SW-MAIN 
board.
No
The reset signal is inputted to 
pin 17 of IC104 on the 
SW-MAIN board.
No
Check the communication line of between 
IC100 and IC104 on the SW-MAIN board.
Check the communication line of between 
IC100 and IC105 on the SW-MAIN board.
No
The waveform of the following is inputted.
SW-MAIN board: IC105 pin 19 (SOFTMUTE)
 
IC105 pin 21 (SCDT)
 
IC105 pin 22 (SCSHIFT)
 
IC105 pin 23 (SCLATCH)
 
IC105 pin 27 (INIT)
Yes
No
Yes
Yes
Yes
The voltage of the following is 1.8 V.
SW-MAIN board: IC106 pin 3
The voltage of the following is 3.3V.
SW-MAIN board: IC108 pin 3
Check the contact between connector 
(CN109) on the SW-MAIN board and 
speaker cable.
Check the contact between speaker 
(SP1) and speaker cable.  
The area surrounding IC104 
on the SW-MAIN board do 
not short-circuits or opens.
Replace the IC104 on the 
SW-MAIN board.
Yes
The area surrounding IC105 on the SW-MAIN 
board do not short-circuits or opens.
Replace the IC105 on the SW-MAIN board.
Replace the IC106 or IC108 on the SW-MAIN 
board.
No
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