Blu Touchbook 7.0 3G, Service Manual

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Troubleshooting
1)
Trouble 1:The tablet can’t be charged when inserting the adapter
Possible Cause:
1) Check if the voltage of CN1914 is above 3.4V. If it is, the touch
between the usb connector and main board is bad ,either the usb
connector ,fpc connector or the soft fpc is bad
2) check U1701,if the welding is ok
3) the LCD is bad , cannot display the charger Icon, change the LCD
module
2)
Trouble 2: No reaction when turns on
Possible Cause:
1) Check if the connector CN1909 is ok, if it is , check the resistor
RV1801 ’state
2) cheek if the battery’s voltage is below3.4V, if it is, please insert the
adapter to charge the tablet
3) check the keyboard fpc: if the fpc is ok ,if it is not ,please change
another, if it is, please check the fpc is well inserted
4) check if the fpc between LCD and main board is ok
5) download the tablet again
3)
Trouble 3: backlight of LCD is not lights after turns on
Possible Cause:
1) check
if the fpc between LCD and main board is ok
2) check if the power VBAT is in good state
3) check the whole Pathway is ok
4) check U901 is ok
the control circuit as below: