Samsung SM-G975F Service Manual page 79

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
R304 while pressing power
key. Is the voltage high?
Check the signal of
AP_PS_HOLD = 1.8V
Check the Clock OSC8000&U12003
Is the frequency 32.768MHz?
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
Yes
Change the FRONT-LCD ASSY
No
Replace the Power key FPCB
Check the output voltage of U12003
L8026 > 0.75V, L8005 > 0.75V,
L8007 > 0.75V, L8008 > 0.75V,
L8010 > 0.75V, L8015 > 1.1V,
No
L8013 > 0.6V, L8014 > 0.85V,
L8012 > 0.75V, L8022 > 1.3V
L8016 > 2.0V, L8002 > 0.75V
If the output voltage is not normal,
Change the U12003.
※ Each voltage level has ±10% margin.
No
Replace the OSC8000 & U12003
※ Test condition (Oscilloscope setting)
: 20.0us.div (time division)
(under 3.0V),
Change the battery.