LG KE990 Service Manual - Page 97

UMSUSB MASS STORAGE trouble

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4. TROUBLE SHOOTING 4.6.2 UMS(USB MASS STORAGE) trouble UMS Initial sequence of KE990 is : USB connected to KE990 → VREG_5V(R335, UMS) go to 5V → VREG_USB_3.3V(R301) go to 3.3V →USB_DATA is triggered → USB work Start NO Cabl e is insert? Cable inser t YES VREG_5V is about to 5 V? YES VREG_USB_3.3V is about to 3.3V? YES MICRO SD function OK? YES Change the Main board NO Check R335, D501 NO Check R301,C529, USB CA BLE NO Follow the micro sd trouble < TOP SIDE > R335(VREG_5V) D501(VREG_5V) C529 (VREG_USB_3.3V) R301(VREG_USB_3.3V) LGE Internal Use Only - 98 - Copyright © 2008 LG Electronics. Inc. All right reserved. Only for training and service purposes

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LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc.
All right reserved.
Only for training and service purposes
4.6.2 UMS(USB MASS STORAGE) trouble
UMS Initial sequence of KE990 is :
USB connected to KE990
→
VREG_5V(R335, UMS) go to 5V
→
VREG_USB_3.3V(R301) go to 3.3V
→
USB_DATA is triggered
→
USB work
4. TROUBLE SHOOTING
- 98 -
Start
VREG_5V is about
to 5V?
VREG_USB_3.3V is
about to 3.3V?
MICRO SD function OK?
Change the Main board
Check R335, D501
Check R301,C529, USB CABLE
Follow the micro sd
troubl
e
NO
YES
YES
YES
NO
NO
Cable is
insert?
YES
Cable inser
t
NO
C529 (VREG_USB_3.3V)
D501(VREG_5V)
< TOP SIDE >
R335(VREG_5V)
R301(VREG_USB_3.3V)