LC-19A1E (serv.man4). Troubleshooting Table - Sharp TV Service Manual (repair manual). Page 9

LC-19A1E-BK/WH

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No sound from EXT5 (AUDIO) connecting an external input 
device.

                                            
<EXT5>
Is PC-S-L audio signal input from J401 to pin (7) of IC301?
Is PC-S-R audio signal input from J401 to pin (3) of IC301?

YES

Is PC-S-L audio signal input to pin (42) of IC501 (AV-SW)? 
Is PC-S-R audio signal input to pin (40) of IC501 (AV-SW)? 

NO

Check Connector SC1202 pins (9) and (10), Connector SC501 
pins (9) and (10) and short circuit.

YES

Is the audio signal (TERMINAL-L/R) properly output from pins 
(34) and (33) of IC501 (AV-SW)? 

NO

Check the Power supply input of pin(38) of IC501, or SDA2/SCL2 
signal of pins (28) and (29) or peripheral circuits.

YES

Is the audio signal (INLP/INRP) output properly from pins (25) 
and (23) of IC302 (A-CODEC)? 

NO

Check pins (4) and (1) of IC302 (A-CODEC), pins (12) and (11) of 
Connector SC1202, audio-mute line (Q301/Q302) or peripheral 
circuits.

YES

Is the audio signal L-CH output to pins (44-46) and (39-41) of 
IC303 (POWER-AMP)? Is the audio signal R-CH output to pins 
(20-22) and (15-17) of IC303 (POWER-AMP) normally?

NO

Check UR12V power supply input pins (3) and (48) of IC303 
(POWER-AMP) or peripheral circuits.

YES

Is the audio signal of pins (1)-(4) of SP-Connector (P301) prop-
erly output?

NO

Check SP-CONNECTOR (P301) and short circuit.

YES

Check SP-BOX (right and left) and WIRE HARNESS.