LG CM5660 Service Manual page 33

6. NO SOUND
There is no sound output in the USB function, repair the set according to the following guide.
6-3. USB FUNCTION
6-3-1. Solution
Please check and replace IC104 on MAIN board.
6-3-2. 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 USB_5V voltage (pin6 of IC104).
2) Check USB D1± or USB D2± from MAIN board to top board.
a. Check 2.0_D1±signals(pin2, pin3 of JK500) or 1.1_D1± signals(pin2, pin3 of JK501) to IC500.
b. If there is any trouble, check the power for IC104.
The power is normal but, if the signal waveform to the IC is distorted or no signal, replace it with a new one.
6-3-3. Service hint (Any picture/ Remark)
D D +
D-
USB D-/D+ (JK500 pin2, pin3)
< Waveform of USB D± signal >
ONE POINT REPAIR GUIDE
3-16
JK500 JK500
(USB2.0) (USB2.0)
< MAIN board top view >
JK501 JK501
(USB1.1) (USB1.1)