The Digital Audio Signal Is Not Output - Sharp LC-42SB45U Service Manual

Does not the sound of the audio signal input to INPUT 3(Composite, Y/C) go out?
MAIN UNIT:
Is the audio signal properly sent to pin (4) (AV3_AudioLIN) and pin
(6) (AV3_AudioRIN) of CN650?
Is the audio signal properly sent to pin (K23) (AV3_LIN) and pin
(K24) (AV3_RIN) of IC U400?
Refer to "No sound output in all modes".
Does not the sound of the audio signal input to INPUT 7 (VGA) go out?
MAIN UNIT:
Is the audio signal properly sent to pin (2) (VGA_AudioLIN) and pin
(3) (VGA_AudioRIN) of CN555?
Is the audio signal properly sent to pin (K25) (VGA_LIN) and pin
(K26) (VGA_RIN) of IC U400?
Refer to "No sound output in all modes".
Does not the sound of the audio signal input to INPUT 4/5/6 (HDMI1/2/3) go out?
Is picture of the signal input from INPUT 4/5/6 displayed?
Refer to "No sound output in all modes".
No digital audio signal output from SPDIF_OUTPUT terminal.
↓
TEREMINAL UNIT:
Is ASPDIF audio signal output from pin (B22) of IC U400 to pin (6)
of connector CN553?
Check IC U400 and its peripheral circuits.
No sound from external input devices (2)
↓
↓
↓YES
↓YES
No sound from external input devices (3)
↓
↓
↓YES
↓YES
No sound from external input devices (4)
↓
↓
↓YES

The digital audio signal is not output (1)

↓
↓NO
2008-03-14
NO
Check the connection to CN650 and the external input device.
NO
Check the line between CN650 and IC U400.
NO
Check the connection to CN555 and the external input device.
NO Check the line between CN555 and IC U400.
NO Refer to "Does not the picture of the HDMI signal input to
HDMI1/2/3 go out?".
YES
Check the connection to SPDIF_OUT and external devices.
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LC-42SB45U