Usb Troubleshooting - LG U370 Service Manual

4. TROUBLE SHOOTING

4.10 USB Troubleshooting

USB Initial sequence of U370 is :
USB connected to U370 power on → USB_VBUS(Q300) go to 5V → USB_D+ go to 3.3V →
USB_DAT is triggered → USB work.
Power on was OK ?
Insert the USB Cable, and
Check Voltage of USB_VBUS
pin of U304 is 5V ?
Voltage of USB_D+ is 3.3V ?
Change the Main board
LGE Internal Use Only
Start
NO
YES
NO
YES
NO
YES
- 92 -
Go to Power on Trouble shooting
Check I/O Connector
Check PM6650
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