LG CU920 - Power on Troubleshooting

LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
- 110 -
4.10 Power ON Troubleshooting
Power On sequence is :
PWR key press → PM_ON_SW_N go to low(VA801),PM6650 KPDPWR_N pin(24) → PM6650
Power Up → VREG_MSMC_1.2V(C732), VREG_MSME_1.8V(C733),
VREG_MSMP_2.7V(C722), VREG_MSMA_2.6V(C720), VREG_TCXO_2.85V(C715) power up
and system reset assert to MSM → Phone booting and PS_HOLD(R702) assert to PMIC
Start
Battery voltage. h ig h er
than 3.10V?
VA801 high to lo w
when key press?
VR EG_ MSMC _1.2V,VR EG_ MSMP_2.7V,
VRE G_MSM E_1.8V, VRE G_TCX O_2.8
5 V,
VR EG_ MSMA _2.6V pow er u p ?
Is clock ok ?
C160 : 19.2 M
X700 : 32 .76 8K h z
Change the Main boar d
Change or c harging the
Battery
Check the K ey Dome
Change the Main board
Check the TXCO
NO
YE S
YE S
YE S
YE S
NO
NO
NO