Usb Trouble - LG U310 Service Manual

4.9 USB Trouble

USB Initial sequence of U310 is :
USB connected to U310 -> USB_VBUS(D504) go to 5V -> USB_D+(D501) go to 3.3V ->
48M Crystal on -> USB_DATA(TPUSBP) 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_VBUS
USB_DATA
(TPUSBP)
Start
NO
YES
NO
to 5V?
YES
NO
YES
NO
YES
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4. TROUBLE SHOOTING
Cable insert
Check D504,USB cable
Check D501
Check X200
X200(48MHz)
USB_D+
USB_D-