Usb Troubleshooting - LG lg530g Service Manual

4.9 USB Troubleshooting

4.9 USB Troubleshooting
USB Initial sequence is :
USB Initial sequence is :
USB connected to I/O connector -> TP1 go to 5V -> USB_DP go to 3.3V -> USB_DN go to 400mV -> USB work.
USB connected to I/O connector  TP1 go to 5V  USB_DP go to 3.3V 
USB_DN go to 400mV  USB work.
Cable is connected ?
Power is ON ?
TP1 is 5V ?
USB_DP is 3.3V ?
Change the main board
Change the main board
Checking Points_MAIN PCB
LGE Internal Use Only
START
Start
Cable is connected ?
NO
Yes
YES
Power is ON ?
NO
Yes
YES
NO
TP1 is 5V ?
Yes
YES
NO
USB_DP is 3.3V ?
Yes
YES
[ USB Troubleshooting Flow ]
[ USB Troubleshooting Flow ]
No
Connect USB cable
Connect USB cable
No
Go to Power on trouble shooting guide
Go to Power on trouble shooting guide
No
Check the USB cable
Check the USB cable
No
Check the USB cable
Check the USB cable
TP1
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4. TROUBLE SHOOTING
LG530G
Only for training and service purposes