LG CM8440, Service Manual

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3-19
ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the TUNER FUNCTION, repair the set according to the
following guide.
6-4. IN THE TUNER FUNCTION
6-4-1. Solution
Please check and replace IC202, TU500 on MAIN board.
6-4-2. How to troubleshoot (Countermeasure)
1) Check if TUNER_LR is entered from Pin1 & 3 of TU101 to IC202(Pin23, 24).
 If no signals, Check +3.3 V for Tuner power.
 Check if the Tuner control signals (CLK, DAT, CE, RST, GPO2) are entered from IC101 to TU101.
If it doesn’t work, replace TUNER with a new one.
2) Check if MCS_BCK, MCS_LRCK, & MCS_MCLK are entered from IC501 to IC202.
3) Check if ADC_DATA is entered from IC202 to IC501.
 If no signal, check +5 V & +3.3 V(ADC) for IC202. If is NG, replace it a new one.
4) Check the following I2S audio signal flow from IC501 to IC600.
 If there is any trouble, check the power for each IC. The power is normal but,
if the signal waveform to the IC is distorted or no signal, replace it with a new one.
5) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide.
 If AMP is damaged, replace it with a new one.
6-4-3. Service hint (Any picture / Remark)
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tjz †syjrG›–GyYX`
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{T
IC501
MLC3730
IC600
TAS5548
PWM
MCS_BCK
MCS_LRCK
IC202
CS5346
TUNER
ADC/MIC_DATA
MCS_MCLK
TUNER_L/R
IR AMP
IRF6775
Jack
Board
MIX_DATA_OUT
< Signal check point >
< TUNER function signal fl ow >