LG LG-YD636, Service Manual

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Checking Flow
START
YES
Check Battery Voltage
> 3.45V ?
NO
Charge of Change Battery and try again
Replace U401
Re-download software & try again
The power-on procedure is completed.
The problem may be elsewhere.
The Phone will power on.
Replace the main board.
Check the contact of power-key
or dome switch
Push power-on key and check
the level change of
U401 PWR_ON_SW/
Check the voltage of
the following port at U401
+2.6V_MSMA
+2.85V_RUIM
+1.9V_MSMC
+2.85V_MSMP
+2.85V_TCXO
+2.6V_RX
+2.6V_TX
Logic level at PWR_ON_SW/
of U401=Low ?
Does it work properly?
Does it work properly?
YES
YES
YES
YES
NO
NO
NO
NO
NO
YES