LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
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4.8.1 USB trouble
USB Initial sequence of KC910 is :
USB connected to KC910
→
USB_VBUS(D502) go to 5V
→
USB_D+(VA501) go to 3.3V
→
USB_DATA is triggered
→
USB work
Start
USB_VBUS i s about
to 5 V?
USB_D+ i s about to 3. 3V?
Chang e th e Main bo ard
Check VA50 4,D502
USB c able
Check VA50 1,U504,U503
NO
YES
YES
NO
Cabl e is insert?
YES
Cable inser t
NO
VA504(USB_VBUS)
U504(USB_D+)
D502(USB_VBUS)
VA501(USB_D+)
U503(USB_D+)
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