LG CJ65 Service Manual page 40

NO SOUND
There is no sound output in the USB FUNCTION, repair the set according to the following guide.
5-3. IN THE USB FUNCTION
5-3-1. Solution
Please check and replace IC500 on MAIN board & IC104 on USB board.
5-3-2. How to troubleshoot (Countermeasure)
1) Check +5V_USB to USB board.
  If the USB LED are turned on, the voltage is okay, if so not, check +5.6 V to pin6 of CN502.
2) Check USB D1± or USB D2± from MAIN board to USB board.
a. Check 2.0_D1±signals(pin U7, U8 ) or 1.1_D1± signals(pin A7, A8 ) to IC500.
b. Check USB± signals to CN502(pin1, 2, 4, 5).
  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.
5-3-3. Service hint (Any picture / Remark)
DSP IC500
176 PIN
Audio DSP-1
USB 2.0 OTG
Main Processor
DSP
Audio DSP-0
133Mhz
USB 1.1
16KB SRAM29KB
ARM
DSP
Host/Device
I-Cache
926EJS
I-Cache 8KB
133Mhz
16KB
400Mhz
SRAM (10K) D-Cache 8KB
D-Cache
I2S (7.1ch)
SDRAM
Controller Boot ROM (20KB) GDMA 2ch
SPDIF (Rx, Tx)
Interrupt
ADPCM
controller
CDROM x8 speed
Decoder PLL
ADC (12bit*5ch) RTC & Wake up
Clock Controller
GDMA 3ch
Timer, Watchdog UART 4ch (Max)
Reset Controller
NAND Controller GPIO (72 Max) I2C 2ch
within BCH codec
Test Controller
SPI 4ch (Max)
14bits ECC SDHC-SDIO 4ch (Max)
12.288 MHZ
PWM
< USB function signal fl ow >
ONE POINT REPAIR GUIDE
USB1_D±
USB2_D±
SRAM29KB
I-Cache 8KB
D-Cache 8KB
FR,FL
D- to pin 1&4 of CN502
D+ to pin 2&5 of CN502
< Waveform of USB D± signal >
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