Samsung Galaxy Tab 4 Service Manual page 21

Level 3 Repair
8-3-1. Power On
Device can`t power on.
Check the Battery Voltage.
Is it more than 3.4V?
Check the power key
(open, etc)
Power-on the phone and check
the power-on sound is ok?
Check the U401 output voltage
(C427,C428 > 1.8V,
C430 > 1.2V)
Check the Clock OSC400
Is that frequency 32KHz?
check the initial operation
END
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Yes
Yes
No
Yes
Yes
No
Charging the battery by TA.
Abnormal
Change the power key
And retry to the power-on operation.
Yes
Change the FRONT ASSY
If the output voltage is not satisfied with normal
No
condition, Change the U401
Change the OSC400
If OSC400 does not still work, Change the U401
This problem is internal oscillator of U401
No
※ Test condition (Oscilloscope setting)
: 20.0us.div (time division)
8-5