Power On; Mobile Phone Does Not Power On - Samsung SM-A505F 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
R5017 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
Yes
No
Yes
Yes
Yes
Yes
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 U5000
L5000 > 0.75V, L5001 > 0.75V, L5002
> 0.75V,
L5003 > 0.75V, L5004 > 0.75V, L5005
No
> 0.75V,
L5006 > 0.75V, L5008 > 1.1V, L5009
> 1.3V, L5010 > 2.0V, L5011 > 0.75V
and other LDO Voltage
If the output voltage is not normal,
Change the U5000
No
Replace the OSC5000
※ Test condition (Oscilloscope setting)
: 20.0us.div (time division)
(under 3.0V),
Change the battery.