Power On Trouble - LG U310 Service Manual

4. BB Trouble Shooting

4.8 Power ON Trouble

Power On sequence of U310 is :
PWR(END) key press -> PM_ON_SW_N go to low(D601),PM6650-2M KPDPWR_N pin(24) ->
PM6650-2M Power Up -> VREG_MSMC_1.25V(C430), VREG_MSME_1.8V(C431),
VREG_MSMP_2.7V(C425), VREG_MSMA_2.6V(C422), VREG_TCXO_2.85V(C416) power up and
system reset assert to MSM -> Phone booting and PS_HOLD(D400)
assert High to PMIC(PM6650-2M).
Start
Battery voltg. higher
than 3.28V?
YES
Press PWR key
Keypad LED on?
YES
D601 high to low
when key press?
YES
YES
Is clock ok?
R406 : 19.2M
X400 : 32.768Khz
YES
Change the Main board
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4. TROUBLE SHOOTING
NO
Change or charging the
Battery
NO
Follow the LED trouble
shoot
NO
Check the Diode
NO
Change the Main board
NO
Check the TXCO