Usb Troubleshooting - LG KU730 Service Manual

4.10 USB Troubleshooting

USB Initial sequence of KU730 is :
USB connected to KU730 -> USB_VBUS go to 5V -> USB_D+ go to 3.3V ->
48M Crystal on -> USB_VP and USB_VN is triggered -> USB work.
Cable is inserted?
USB_VBUS is 5V?
USB_D+ is 3.3V?
48M clock is running?
Change the Main board
Start
NO
YES
NO
YES
NO
YES
NO
YES
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4. TROUBLE SHOOTING
Insert cable
Check R406, C428,
D504,USB Cable
Check D504
Check X200