Sharp LC-40D68UT Service Manual page 57

INPUT-3 No audio.
Is INPUT-3 selected on the input select menu screen?
Is the audio output selected for "VARIABLE" on the menu
screen?
Does the audio signal come from pins (5) (L) and (4) (R) of input
terminal (J501) to pins (14) (L) and (5) (R) of IC503 (AUDIO
SWITCH)?
Does the audio signal come from pins (13) (L) and (3) (R) of
IC503 to pins (B2) (L) and (A1) (R) of IC8001 (CPU)?
Does the audio signal come from pins (C4/A3) (SPOUT_L/R) of
IC8001 (CPU) to pins (3) (INLP), and (7) (INRP) of IC2701
(AMP)?
Is the audio output from IC2701 as specified?
Check the connector (P2701), speakers and their peripheral cir-
cuits.
YES
YES
YES
YES
YES
YES
No audio (1)-2
NO Refer to ":No external input video [INPUT-3]".
NO Set the audio output to "FIXED".
NO Check the line between J501 and IC503.
NO Check IC503/IC8001 and its peripheral circuits.
(IC502, Q509, Q510, etc.)
Check the audio signal lines between IC503 and IC8001.
1) IC503: pin (13) (A_INL), pin (3) (A_INR)
2) SC501/SC601: pin (15), pin (14)
3) IC8001: pin (B12), pin (A1)
Check the audio switching signals (AUDIO_CTL0/1) between
IC503 and IC8001.
1) IC8001: pin (L1) (AUDIO_CTL0), pin (K1) (AUDIO_CTL1)
2) SC1101/SC1201: pin (17), pin (18)
3) Q510: pin (2), Q509: pin (2)
4) IC503: pin (10), pin (9)
NO Check the line between IC8001 and IC2701, and their peripheral
circuits (Q1306/Q1307, AMP_MUTE line, etc.).
NO Check IC2701 and its peripheral circuits.
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LC-40D68UT