Mobile Phone Does Not Power On - Samsung SM-M307F Service Manual

8. Level 3 Repair
8-4-1. Power On

Mobile phone does not power on.

Check the Battery Voltage.
Is it more than 3.8V?
Power-on the phone and check
the power-on sound
or motor Vibration.
Sound or Vibration is ok?
Check the voltage level at
R5023 while pressing power
key. Is the voltage high?
Check the signal of
TRST_N = 1.8V
Check the Clock OSC5000
Is the frequency 32.768kHz?
Check the initial operation
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Yes
No
Yes
No
No
Yes
No
Yes
No
Yes
No
Yes
No
END
Charging the battery by TA.
No
If its voltage level is extremely low
Change the battery.
Yes
Change the FRONT-LCD ASSY
No
Replace the Power key FPCB
Check the output voltage of U5000
L5000 > 0.75V, L5001 > 0.75V, L5002
> 0.75V,
L5003 > 0.75V, L5004 > 0.75V, L5005
No
> 0.75V,
L5006 > 0.75V, L5007 > 1.1V, L5008
> 1.3V, L5009 > 2.0V, L5010 > 0.75V
and other LDO Voltage
If the output voltage is not normal,
Change the U5000
※ Each voltage level has ±10% margin
No
Replace the OSC5000
※ Test condition (Oscilloscope setting)
: 20.0us.div (time division)
(under 3.0V),