LC-42D43U
4 – 1
LC-42D43U
Service Manual
CHAPTER 4. TROUBLESHOOTING TABLE
[1] TROUBLESHOOTING TABLE
No audio output during UHF/VHF reception
Is SIF output from the tuner (TU1101_Pin15) normal? NO Check the tuner and peripheral circuits.
YES
Is input signal fed to pin 21 of IC1401 (SIF Demodulator) normal? NO Check the filter circuits (Q1102-3) and peripheral circuits.
YES
Are audio signals from pins 29 and 30 of IC1401 to pins 51 and
52 of IC1404 (CODEC) normal?
NO Check between pins 29 and 30 of IC1401 and pins 51 and 52 of
IC1404 (CODEC).
YES
Are audio outputs of pins 38 and 39 of IC1404 normal?
NO
Are the DSP_LRCK, DSP_BCKIN, DSP_SDIN1, DSP_MCLK,
DSP_SDOUT1, DSP_SDOUT2 signals sent from IC1404 to
IC1407 (DSP) normally?
YES
YES
Check IC1404 and peripheral circuits.
Is audio input from pins 38 and 39 of IC1404 to pins 3 and 5 of
IC2701(STEREO_AMP) normal?
NO Check the circuits between pins 38 and 39 of IC1404 and pins 3
and 5 of IC2701. (MUTE circuits: Q1307, Q1314, Q1313)
YES
Is audio output from IC2701 normal? NO Check IC2701 and peripheral circuits.
YES
Check the connector (P2703) of TERMINAL_UNIT and around
the speakers.
No monitor audio output
Is monitor audio output set to “Variable”? YES Reset monitor audio output to “Fixed”.
NO
Are audio output pins 40 and 41 of IC1404 (CODEC) normal? NO Check IC1404 and peripheral circuits.
YES
Are audio output pins 7 and 1 of IC1408 (Buffer_AMP) normal? NO Check IC1408 and peripheral circuits.
YES
Check between IC1408 and MONITOR OUTPUT terminal (J502).
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