Power On Troubleshooting - LG U370 Service Manual

4.8 Power ON Troubleshooting

Power On sequence of U370 is :
PWR key press → PM_ON_SW_N go to low, PM6650 KPDPWR_N (pin24) → PM6650 Power Up →
VREG_MSMC_1.2V, VREG_MSME_1.8V, VREG_MSMP_2.7V, VREG_MSMA_2.6V,
VREG_TCXO_2.85V power up and system reset assert to MSM6245 → Phone booting and
PS_HOLD assert to PMIC
Battery Voltage is higher
Press PWR_ON key ?
MSMC_1.2V , MSMP_2.7V
MSME_1.8V , MEMA_2.6V
Check TCXO / Sleep Clock
R306 : TCXO_MSM ( 19.2 Mhz)
TP311 : ( 32.768 Khz)
Change the Main board
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Start
than 3.2 V ?
YES
YES
Check Belows,
VREG_TCXO_2.85V
YES
YES
4. TROUBLE SHOOTING
NO
Insert Well Charged Battery
or Charging the Battery
NO
Check the Key Dome
NO
Try to replace PM6650 ( Level 3)
or , Change the Main Board
NO
Check the TCXO
and PM6650
- 87 -
LGE Internal Use Only