LG KG920 - Page 89

4. TROUBLE SHOOTING
- 90 -
CHECKING FLOW
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 U100
Logic level at KEYON signal of U100
= HIGH?
Does it work properly?
THE PHONE WILL
POWER ON.
Charge or Change Battery
Check the contact of power key
Or dome-switch
Replace U100
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
Figure 4-27.