Only For Training And Service Purposes - LG KC910 Service Manual

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
Cabl e is insert?
USB_VBUS i s a bout
to 5 V?
USB_D+ i s about to 3. 3V?
Chang e th e Main bo ard
< BOTTOM SIDE >
U503(USB_D+)
U504(USB_D+)
Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

Start
NO
YES
NO
YES
NO
YES
VA501(USB_D+)
VA504(USB_VBUS)
D502(USB_VBUS)
4. TROUBLE SHOOTING
Cable inser t
Check VA50 4,D502
USB c able
Check VA50 1,U504,U503
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LGE Internal Use Only