Usb Trouble - LG U8210 Service Manual

4. TROUBLE SHOOTING

4.11 USB Trouble

USB Initial sequence of U8210 is :
USB connected to U8210 → USB_VBUS(D520) go to 5V → USB_D+ go to 3.3V → 48M Crystal on →
USB_VP and USB_VN is triggered → USB work.
Cable is insert?
USB_VBUS is about
USB_D+ is about to 3.3V?
Change the Main board
Start
YES
to 5V?
YES
YES
48M is run?
YES
NO
Cable insert
NO
Check U404,D520,USB
NO
Check U404
NO
Check X100
- 110 -
cable