LG VX5400 Service Manual page 115

Checking Flow
START
Check Voltage at VBUS
of U500= 5.0V ?
X200 is working?
X200 is working?
Oscillator frequency = 48 MHz?
Oscillator frequency = 48 MHz?
Logic level at
USB_SUSPEND = Low?
The USB interface will work properly The USB interface will work properly
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Only for training and serving purposes
NO
YES
NO
YES
NO
YES
Check the soldering U500
YES
Check the contact state of Data-
cable or Replace U500
Check the soldering X200,R300
YES
Replace X200,R300
Check the soldering U500
YES
Replace U500
-115-
NO
Re-soldering
U500
NO
Re-soldering
X200,R300
NO
Re-soldering
U500
LGE Internal Use Only