Usb Troubleshooting - LG KU800 Service Manual

4. TROUBLE SHOOTING

4.10 USB Troubleshooting

USB Initial sequence of KU800 is :
USB connected to KU800 → USB VBUS SWITCH -> USB_VBUS go to 5V → USB_D+ go to 3.3V
48M Crystal on → USB_VP and USB_VN is triggered → USB work.
48M clock is running?
Change the Main board
Start
Cable is inserted?
YES
USB_VBUS is 5V?
YES
USB_D+ is 3.3V?
YES
YES
NO
Insert cable
NO
Check VA506,R407, C422,
Q1001,USB Cable
NO
Check VA503
NO
Check X200,R204
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