LG KG290 - Page 68

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Only for training and service purposes
4. TROUBLE SHOOTING
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START
Check Battery Voltage
> 3.35V
Push power-on key
And check the level change
of PWRKEY
Check the voltage of
The LDO outputs at U103
Logic level at KEYON of U103
= HIGH
Does it work properly?
THE PHONE WILL
POWER ON.
Charge or Change Battery
Check the contact of power key
Or dome-switch
Replace U103
VCORE=1.8V VVCXO=2.75V
VMEM=2.8V VSIM=1.8V or 2.85V
VEXT=2.8V VABB=2.75V
VMIC=2.5V
Re-download software
The power-on procedure is
Completed. The problem may
be elsewhere.
Does it work properly?
Replace the main board
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
Checking Flow