Base Band Part - LG GU280 Service Manual

4.7. Base band part

4.7.1 Power ON Troubleshooting
Power On sequence is :
PWR key press KPDPWR_N (QSC6240 KPDPWR_N pin(AA10)) go to low(VA106)
VREG_MSMC_1.2V(C203), VREG_RF1(C217), VREG_MSME_1.8V(C237), VREG_MSMP_2.6V(C229),
VREG_RF2_1.4V(C259), VREG_MPLL_1.3V(C240), VREG_USB2P6(C227), VREG_TCXO_2.85V(C239) power up and
system reset assert to MSM
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Only for training and service purposes
Phone booting and PS_HOLD assert to PMIC
Start
Battery voltage. higher
than 3.20V?
YES
VA106 go to low
when key press?
YES
VREG_MSMC_1.2V
VREG_RF1_2.3V
VREG_MSME_1.8V
VREG_MSMP_2.6V
VREG_RF2_1.4V
VREG_MPLL_1.3V
VREG_USB2P6
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
Check the TCXO & Sleep Cystal
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4. TROUBLE SHOOTING
QSC6240 Power Up
LGE Internal Use Only