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Only for training and service purposes
4. TROUBLE SHOOTING
4.3 USB Troubleshooting
USB Initial sequence is : Isert USB Cable Î USB_VBUS +5V Check Î IC400 triggered USB IF work
USB Troubleshooting
START
Cable is insert
physically?
Change CN400
No
Yes
Change the main board
Is TP1_FL401(VBUS) voltage 5.1V?
Change CN401
No
Yes
TP2_C409(LDO4.9V)
OUTPUT is about 5V?
Change the U401
No
Yes
Is IC401 OUTPUT is TP3_C265(USB_
DM,USB_DP) signal OK?
Change the IC401
No
Yes
[ USB Troubleshooting Flow ]