Usb Trouble - LG U890 Service Manual

4.9 USB Trouble

USB Initial sequence of U890 is :
USB connected to U890 -> USB_VBUS(U403 Pin_4) go to 5V -> USB_D+(U403 Pin_1) go to 3.3V ->
48M Crystal on -> USB_DATA(TP_210) is triggered -> USB work.
Cable is insert?
USB_VBUS is about
USB_D+ is about to 3.3V?
48M is run?
Change the Main board
USB_DATA
(TP200)
USB_D-
USB_D+
USB_VBUS
Start
NO
YES
NO
to 5V?
YES
NO
YES
NO
YES
- 97 -
4. TROUBLE SHOOTING
Cable insert
Check U403,USB cable
Check U403
Check X200
X200(48MHz)