LG CM9520, Service Manual

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3-32
ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the PORT. IN FUNCTION, repair the set according to the
following guide.
6-6. IN THE PORT. IN FUNCTION
6-6-1. Solution
Please check and replace IC202 on MAIN board.
6-6-2. How to troubleshoot (Countermeasure)
1) Check PT_L/R signal from Main board to USB board.
2) Check if PT_LR is entered from Pin1 & 3 of CN3M01 to Pin1 & 3 to CN202.
3) Check POT_L/R signals to IC202(Pin21, 22).
4) Check if ADC_BCK, ADC_LRCK, & DAC_MCLK are entered from IC501 to IC202.
5) 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.
6) Check the following I2S signal flow from IC501 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.
7) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide on Item 6-3.
If AMP is damaged, replace it with a new one
6-6-3. Service hint (Any picture / Remark)
kRG›–G—•GXXG–Gju]WY
h| †sG›–GyYWY
w{†yG›–G—•YY
hkj†ijrG›–GyYX]
hkj†kh{hGG›–GyYX\
hkj†syjrG›–GyYX`
hkj†tjsrG›–GyYYX
pjYWY
w{†sG›–G—•YX
{T
IC501
MLC3700
IC602
PS9854
PWM
IC801
FS503B
BEAT BOX
AMP IC
TAS5631
DAC_BCK
DAC_LRCK
IC202
CS5346
DAC_DATA DAC_MCLK
POT. IN
ADC_DATA DAC_MCLK
MIC
Board
POT_L/R
BEAT_DATA
< Signal check point >
< PORT. IN function signal fl ow >