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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4.9 USB Troubleshooting
USB Initial sequence of TU550 is :
USB connected to TU550 power on
→
USB_VBUS(Q501) go to 5V
→
USB_D+ go to 3.3V
48M Crystal on
→
USB_VP and USB_VN is triggered
→
USB work.
Start
Q501 3 pin is 5V?
USB_D+ is 3.3V?
48M clock is running?
Change the Main board
Check Q501
Check U505
Check X200
NO
YES
YES
YES
NO
NO
Cable is inserted?
YES
Insert cable
NO
Power is on?
YES
Go to power on trouble shooting
NO
Summary of Contents for TU550
Page 1: ...Date May 2007 Issue 1 0 Service Manual Model TU550 Service Manual TU550 Internal Use Only ...
Page 185: ...Note ...
Page 186: ...Note ...