Usb Trouble; Usb_Dat; G4 H4 Usb_Se0; Usb_D+ Usb_D - LG KF310 Service Manual

4. TROUBLE SHOOTING

4.2 USB trouble

USB Initial sequence of KF310 is :
USB connected to KF310
USB_DATA is triggered
LGE Internal Use Only
→
USB_VBUS(VA4003) go to 5V
→
USB work
start
Cable is insert ?
YES
USB_VBUS is
About to 5V?
YES
USB_D+ is about to 3. 3V?
YES
start
- 64 -
→
USB_D+(VA4002) go to 3.3V
NO
Cable insert
NO
Check VA 4003
NO
Check VA 4002
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Only for training and service purposes
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USB D+ (VA4002)
USB_VBUS(VA4003)