LG RAT376B Service Manual page 33

NO SOUND
There is no sound output in the AUX FUNCTION, repair the set according to the fol-
lowing guide.
5-4. IN THE AUX FUNCTION
5-4-1. Solution
Please check and replace IC401 on MAIN board.
5-4-2. How to troubleshoot (Countermeasure)
1) Check AUX_L/R signals to IC401 (Pin7, 8).
2) Check if DAC_BCK, DAC_LRCK, & DAC_MCLK are entered from IC801 to IC401.
3) Check if ADC_DATA is entered from IC401 to IC801.
If no signal, check +5 V & +3.3 V(ADC) for IC401. If is NG, replace it a new one.
4) Check the following I2S signal flow from IC801 to IC602. (Refer to Item 5-1.)
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 5-2.
If AMP is damaged, replace it with a new one.
5-4-3. Service hint (Any picture / Remark)
AUX_L/R
IC401
CS5346
DAC_MCLK ADC_DATA
DAC_BCK
DAC_LRCK
IC801
MLC9800
DAC_DATA
DAC_MCLK
< AUX function signal fl ow >
ONE POINT REPAIR GUIDE
AUX
IC602
AMP IC
PS9850
TAS5612
PWM
3-14
< Signal check point >