Power On Trouble Shooting - LG -E405 Service Manual

4.10 Power ON Trouble Shooting

Power On sequence of E405 is :
Power key press -> KPD_PWR_N go to low -> PM8029 Power Up -> VREG_MSMC1_1.1V (L400), VREG_MSMC2_1.1V
(L401), VREG_MSME_1.8V (L402), VREG_P3_2.85V (C453), VREG_MSMA1_2.6V (C448), VREG_MSMA2_1.2V (C444) VREG_
TCXO_2.85V (C449) power ON -> Phone booting and PS_HOLD(D401) go to High
Battery voltage higher than 3.70V(OCV)?
LGE Internal Use Only
START
Yes
TP1(R8010) high to low
when key press?
Yes
Check below power output
(VREG_MSMC1_1.1V)
(VREG_MSMC2_1.1V)
(VREG_MSME_1.8V)
(VREG_P3_2.85V)
(VREG_MSMA1_2.6V)
(VREG_MSMA2_1.2V)
(VREG_TCXO_2.85V)
Yes
Is clock ok?
TP2 (X2000) : 19.2M
Yes
Redownload SW image
No
Change or charging the Battery
No
Check correctly working power key
No
Change the Main board
No
Change the Main board
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4. TROUBLE SHOOTING
Only for training and service purposes