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Only for training and service purposes
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5. Trouble shooting
GW520 service manual
5.4 USB Trouble
END
Is VBUS_USB (C306)
about 5.1V?
Check TP1
Is USB function ok?
Cable is inserted?
Cable insert
1. Change cable
2. Check soldering
or change FL300
NO
YES
NO
YES
NO
YES
Start
Check soldering
or change U301
Change U301
or main board
NO
Does VMUIC_DM
connect USB_DM?
And does VMUIC_DP
connect USB_DP?
Check TP2
Checking Flow
END
Is VBUS_USB (C306)
about 5.1V?
Check TP1
Is USB function ok?
Cable is inserted?
Cable insert
1. Change cable
2. Check soldering
or change FL300
NO
YES
NO
YES
NO
YES
Start
Check soldering
or change U301
Change U301
or main board
NO
Does VMUIC_DM
connect USB_DM?
And does VMUIC_DP
connect USB_DP?
Check TP2
Checking Flow