LG KE990 Service Manual - Page 96
USB trouble
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4. TROUBLE SHOOTING 4.6.1 USB trouble USB Initial sequence of KE990 is : USB connected to KE990 → USB_VBUS(C540) go to 5V → USB_D+(VA202) go to 3.3V → 48M Crystal on → USB_DATA is triggered → USB work Start NO Cabl e is insert? YES USB_VBUS is about NO to 5 V? YES NO USB_D+ i s about to 3. 3V? YES NO 48MHz is r un? YES Chang e th e Main bo ard Cable inser t Check C540, R514,U500 USB c able Check VA50 0,U507,U304 Check X200 VA500(USB_D+) X200(48MHz) R514(USB_VBUS) C540(USB_VBUS) U500(USB_VBUS) U507(USB_D+) U304(USB_D+) Copyright © 2008 LG Electronics. Inc. All right reserved. Only for training and service purposes - 97 - LGE Internal Use Only
LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc.
All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
- 97 -
4.6.1 USB trouble
USB Initial sequence of KE990 is :
USB connected to KE990
→
USB_VBUS(C540) go to 5V
→
USB_D+(VA202) go to 3.3V
→
48M
Crystal on
→
USB_DATA is triggered
→
USB work
Start
USB_VBUS is about
to 5V?
USB_D+ i s about to 3. 3V?
48MHz is run?
Chang e th e Main bo ard
Check C540, R514,U500
USB cable
Check VA50 0,U507,U304
Ch
eck X200
NO
YES
YES
YES
NO
NO
Cable is
insert?
YES
Cable inser
t
NO
X200(48MHz)
C540(USB_VBUS)
U507(USB_D+)
R514(USB_VBUS)
U500(USB_VBUS)
VA500(USB_D+)
U304(USB_D+)