LG CMS4540F/W Service Manual page 30

5. NO SOUND
There is no sound output in the CD FUNCTION, repair the set according to the follow-
ing guide.
5-1. IN THE CD FUNCTION
5-1-1. Solution
Please check and replace IC501, IC601 on MAIN board.
5-1-2. How to troubleshoot (Countermeasure)
1) Check CD_BCLK, CD_LRCK, & CD_DOUTA signals from IC407 to IC501.
If no signal, check if the RF & servo signals from MD is entered to IC407.
Refer to the "No operation of MD" guide on Item 4.
2) Check the following I2S signal flow. < I2S audio signal Interface >
- DAC_BCK : IC501_Pin E1 --> IC601_Pin23
- DAC_LRCK : IC501_Pin D1 --> IC601_Pin22 (44.1 kHz)
- DAC_DATA : IC501_Pin E2 --> IC601_Pin24
- DAC_MCLK : IC501_Pin D2 --> IC401_Pin44
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.
3) Check if "Digital audio AMP block" on Item 5-2 is normal.
5-1-3. Service hint (Any picture / Remark)
P/UP
IC407
LC78615E
(New)
M
12.288MHZ
PWM
TAS5548
< I2S Signal Flow >
ONE POINT REPAIR GUIDE
DSP IC501
MLC3730
176PIN BGA
FR,FL
TAS5612LA
Woofer
TAS5612LA
3-11
MCS_MCLK (16.93MHz)
< Waveform of I2S audio interface signals >
MCS_BCK(1.4MHz)
MCS_DATA_OUT
MCS_LRCK(44.1KHz)