LG OK75 - Troubleshooting: No Sound (Tuner Function)

3-18
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Only for training and service purposes.
< MAIN board bottom view >
IC301
IC301
ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the TUNER function, repair the set according to the following guide.
6-5. TUNER FUNCTION
6-5-1. Solution
Replace IC301 on MAIN board.
6-5-2. How to troubleshoot (Countermeasure)
1) Check if TUNER_LR is entered from pin13, 14 of IC302 to IC301(pin27, 28)
 If no signals, check AVCC_3.3V for tuner power.
 Check if the tuner control signals (CLK, DAT, CE, RST, SLT) are entered from IC501 to IC302.
If it doesn’t work, replace IC302 with a new one.
2) Check if MCS_BCK, MCS_LRCK, & MCS_MCLK are entered from IC501 to IC201.
3) Check if ADC_DATA is entered from IC301 to IC501.
 If no signal, check AVCC_3.3V & DVCC_3.3V (ADC) for IC301. If is NG, replace it with a new one.
4) Check the following I2S audio signal flow from IC501 to IC601. (Refer to Item 6-2.)
 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 on Item 6-1.
 If AMP is damaged, replace it with a new one.
6-5-3. Service hint (Any picture/ Remark)
< TUNER function signal fl ow >
Pin15:DSPI_MCLK
Pin15:DSPI_MCLK
Pin16:DSPI_LRCK
Pin16:DSPI_LRCK
Pin17:DSPI_BCK
Pin17:DSPI_BCK
Pin1:A_IN_L
Pin1:A_IN_L
Pin2:A_IN_R
Pin2:A_IN_R