Power On Troubleshooting - LG L705i Service Manual

4.6. Power ON Troubleshooting

Power On sequence of L705i is :
PWR key press → KEY_ON_SW_N go to low,PM6650 KPDPWR_N pin(24) → PM6650 Power Up
→ VREG_MSMC_1.375V(C429), VREG_MSME_1.8V(C430), VREG_MSMP_2.7V(C423),
VREG_MSMA_2.6V(C420), VREG_TCXO_2.85V(C400) power up and system reset assert to MSM
→ Phone booting and PS_HOLD(D400) assert to PMIC
Battery voltage. higher
VREG_MSMC_1.375V,VREG_MSME_1.8V,
VREG_MSMP_2.7V, VREG_TCXO_2.85V,
VREG_MSMA_2.6V power up?
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Only for training and service purposes
Start
than 3.3V?
YES
VA601 high to low
when key press?
YES
YES
Is clock ok?
R408 : 19.2M
X400: 32.768Khz
YES
Change the Main board
- 95 -
4. TROUBLE SHOOTING
NO
Change or charging the
Battery
NO
Check the Key Dome
Or Check Main to Sub Con.
NO
Change the Main board
NO
Check the TXCO & Crystal
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