LG KE990 Service Manual - Page 93

Power on trouble

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4. TROUBLE SHOOTING 4.6 Power on trouble Power on sequence of KE990 is : PWR key press → PM_ON_SW_N go to low (VA700, PM6635-2M KPDPWR_N pin#24) → PM6635-2M Power Up → VREG_MSMC_1.2V(C560), VREG_MSME_1.8V(R520), VREG_MSMP_2.7V(R513), VREG_MSMA_2.6V(R508), VREG_TCXO_2.85V(C510) power up → PON_RESET_N assert to MSM → Phone booting & PS_HOLD(D500) assert High to PMIC(PM6635-2M) Start Battery vo lt g. higher than 3 .2V? YES Press PW R key Keypad L ED on? YES VA700 h igh to low when key press? YES NO Change or charging the Batt ery NO Follow the LED trouble shoot NO Check open Pattern of power button Check Dome Sheet VREG_MSMC_1.2V, NO VREG_MSMP_2.7V, VREG_MSME_1.8V VREG_TCXO_2.85V, VREG_MSMA_2.6V Power up? Chang e the Main board YES NO Is c lock ok ? X100 : 19.2M X500 : 32.768Khz YES Chang e th e Main board Check the TXCO and SLEEP CRYSTAL LGE Internal Use Only - 94 - Copyright © 2008 LG Electronics. Inc. All right reserved. Only for training and service purposes

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LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc.
All right reserved.
Only for training and service purposes
4.6 Power on trouble
Power on sequence of KE990 is :
PWR key press
→
PM_ON_SW_N go to low (VA700, PM6635-2M KPDPWR_N pin#24)
→
PM6635-2M Power Up
→
VREG_MSMC_1.2V(C560), VREG_MSME_1.8V(R520),
VREG_MSMP_2.7V(R513), VREG_MSMA_2.6V(R508), VREG_TCXO_2.85V(C510) power
up
→
PON_RESET_N assert to MSM
→
Phone booting & PS_HOLD(D500) assert High to
PMIC(PM6635-2M)
4. TROUBLE SHOOTING
- 94 -
Start
Battery voltg. higher
than 3 .2V?
Press PW R key
Keypad LED on?
VA700 high to low
when key press?
VREG_MSMC_1.2V,
VREG_MSMP_2.7V, VREG_MSME
_1.8V
VREG_TCXO_2.85V,
VR
Power up?
EG_MSMA_2.6V
Is clock ok?
X100 : 19.2M
X500 : 32.768Khz
Change the Main board
Change or charging the
Batt ery
Follow the LED trouble
shoot
Check open Pattern
of power button
Check Dome Sheet
Change the Main board
Check the TXCO and SLEE
P CRYSTAL
NO
YES
YES
YES
YES
YES
NO
NO
NO
NO