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4. TROUBLESHOOTING
Checking Flow
Check Battery Voltage
Push power-on key
And check the level change
Check the voltage of
The LDO outputs at U100
Logic level at KEYON(POWER KEY)
of U101= HIGH
Does it work properly?
THE PHONE WILL
POWER ON.
START
NO
> 3.35V ?
YES
NO
of PWRKEY
YES
NO
VCORE=1.8V
VMEM=2.8V
YES
VEXT=2.8V
VABB=2.75V
NO
YES
NO
The power-on procedure is
Completed. The problem may
be elsewhere.
YES
Charge or Change Battery
Check the contact of power key
Or dome-switch
Replace U100
VVCXO=2.75V
VRTC=1.8V
VSIM=2.85V (when sim card is inserted)
VMIC=2.5V
Re-download software
Does it work properly?
Replace the main board
- 70 -
NO
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