Sharp LC-90LE740X Aquos, Service Manual

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LC-90LE740X
6 – 21
No audio signal at Digital Audio Output terminal (Analog sound heard)
No INPUT-1/2/3/4 (HDMI) audio. No audio at digital broadcast signal reception.
If no video appears, refer to “No external input video (HDMI)
[INPUT-1/2/3/4]”. If no video appears, refer to “No video at digital broadcast signal
reception”.
Is there the SPDIF signal output (CPU_ASPDIF) at pin (AR16) of IC3301 (CPU)?
YES
NO
Check the IC3301 and its peripheral circuits.
Is there the SPDIF signal (OPT_OUT) input at pin (2) of IC503 (SPDIF BUFFER & SPDIF-MUTE)?
YES
NO
Check the line between IC3301 and IC503.
Is there the MUTE signal input at pin (1) of IC503? (usual: High, Mute: Low)
YES
NO
Check the AUDIO_MUTE and their peripheral circuits (Q505, etc.).
Is there the SPDIF signal input at pin (1) of D527 (OPTICAL OUTPUT)?
YES NO
Check the speakers and the optical cable. Check D527 and its peripheral circuits.
No optical output under the following conditions as per HDMI requirements.
* Audio contents protected.
* Audio frequency beyond 48kHz.
* Audio bit length beyond 16bits.