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4. TROUBLE SHOOTING
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4.10 Power ON Troubleshooting
Power On sequence of KS20 is :
PWR key press(Key FPCB) -> KPDPWR_ON go to low(D119),PM7540 KPDPWR_N pin(C12) ->
PM7540 Power Up -> VMSMC1_1.2V(C338), VMSMC2_1.2V(C339), VMSME_1.8V(C340),
VMSMP_2.6V(C352), VMSMA_2.6V(C351), VTCXO_2.85V(C355) power up and system reset
assert to MSM -> Phone booting and PS_HOLD(D311) assert to PMIC
Start
Battery voltage. higher
than 3.20V?
D119 high to low
when key press?
VMSMC1_1.2V, VMSMC2_1.2V,
VMSMP_2.6V, VMSME_1.8V,
VTCXO_2.85V, VMSMA_2.6V power up?
Is clock ok?
R314 : 19.2M
X300 : 32.768Khz
Change or charging the
Battery
Check the Key Dome
Change the Main board
Check the TXCO
NO
YES
YES
YES
YES
NO
NO
NO
Check an U100 SMT status
by X-ray
Exchange U100 or
Change the Main board
And Retest
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