LC-42X20E (serv.man4). Troubleshooting Table - Sharp TV Service Manual (repair manual). Page 7

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LC-42XL2E/S/RU, LC-46XL2E/S/RU, LC-46X20E/S/RU, LC-52XL2E/S/RU, LC-52X20E/S/RU
4 – 7
The audio signal is not output (3)
                                             
The audio signal of MONITOR is not output from EXT2 (SCART). 
TEREMINAL UNIT:               
Is audio signal sent to pins (3/L-ch) and (1/R-ch) of SCART2 
(SC503)?
YES
Check the connection to SCART2 and external devices.
NO
Is S2-MUTE-LINE [MAIN_UNIT pin (91) of IC9101 (CPLD)] at H?
YES
Check the peripheral circuits of IC9101 and S2-MUTE_LINE.
(Q501, Q503, etc.)
NO
Is audio signal sent to pins (3/L-ch) and (13/R-ch) of IC7510 
(SW)?
YES
Check the line between IC7510 and SC503.
(Q506, Q505, etc.)
NO
Is audio signal input to pins (1/L-ch) and (12/R-ch) of IC7510?
YES
Check IC7510 or peripheral circuits.
(SC_AUD_SEL_LINE, etc.)
NO
Is audio signal sent to pins (40/L-ch) and (41/R-ch) of IC1404 
(CODEC)?
YES
Check the line between IC7510 and IC1404.
(IC1405, etc.)
NO
Check IC1404 and its peripheral circuits.
The audio signal is not output (4)
                                             
No audio signal output from AUDIO_OUTPUT terminal.
TEREMINAL UNIT:               
Is audio signal output to pin (4/L-ch), (2/R-ch) of audio output ter-
minal J503?
YES
Check the connection to J502 and external devices.
NO
Do pin (72)] of MONITOR_MUTE_LINE [IC506 
(VIDEO_SELECTOR), pin (55)] of MUTE-A_ALL_LINE 
[MAIN_UNIT IC2002 (UCON) become H?
YES
Check the IC506,IC2002, its peripheral circuit and 
MONITOR_MUTE_LINE, MUTE-A_ALL_LINE.
(Q512, Q511, D551, etc.)
NO
Is the audio signal output of pins (40/L-ch) and (41/R-ch) of 
IC1404 (CODEC)?
YES
Check the line between IC1404 and J503.
(IC1405, Q509, Q510, etc.)
NO
Check IC1404 and its peripheral circuits.
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