Power On Troubleshooting - LG BL42k Service Manual

Power ON Troubleshooting

4. Base band part
4.7 Power ON Troubleshooting
Power On sequence is :
PWR key press PM_ON_SW_N
Power Up VREG_MSMC_1.2V(C261), VREG_MSME_1.8V(C209), VREG_MSMP_2.6V(C414),
VREG_RFRX2_1.3V(C232), VREG_TCXO_2.85V(C239) power up and system reset assert to QSC6270
booting and PS_HOLD assert to QSC6270
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Only for training and service purposes
QSC6270 KPDPWR_N pin(AA2) go to low(KEY BOARD VA1)
Start
Battery voltage. higher
than 3.20V?
YES
VA106 go to low
when key press?
YES
VREG_MSMC_1.2V
VREG_MSME_1.8V
VREG_MSMP_2.6V
VREG_TCXO_2.85V
power up?
YES
Is clock ok?
X201 : 32.768KHz
C108 : 19M
YES
Change the main board
NO
Change or charging the Battery
NO
Check the Key Dome
NO
Change the main board
NO
Change the TCXO & Sleep Crystal
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4. TROUBLE SHOOTING
BL20
QSC6270
Phone
LGE Internal Use Only