Trouble Shooting; Power On Trouble - LG KF690 Service Manual

4. TROUBLE SHOOTING

4. TROUBLE SHOOTING

4.1 Power on trouble

Power on sequence of KF690 is :
→ PM_ON_SW_N go to low (VA100, PM6635 KPDPWR_N pin#24) →
PWR key press
PM6635 Power Up → VREG_MSMC_1.2V(C445), VREG_MSME_1.8V(C442),
VREG_MSMP_ 2.7V(C425), VREG_MSMA_2.6V(C424), VREG_TCXO_2.85V(C409) power
up → PON_RESET_N assert to MSM → Phone booting & PS_HOLD(D400) assert High to
PMIC(PM6635)
VREG_MSMP_2.7V, VREG_MSME_1.8V VREG_MSMP_2.7V, VREG_MSME_1.8V
VREG_MSMA_2.6V power up? VREG_MSMA_2.6V power up?
LGE Internal Use Only
Start Start
Check the battery terminal Check the battery terminal
broken or bent broken or bent
NO NO
Battery volt. higher Battery volt. higher
than 3.22V? than 3.22V?
YES YES
R414 high to low R414 high to low
when key press? when key press?
YES YES
VREG_MSMC_1.2V, VREG_MSMC_1.2V,
VREG_TCXO_2.85V, VREG_TCXO_2.85V,
YES YES
Press PWR key Press PWR key
Keypad LED on? Keypad LED on?
YES YES
LCD display OK? LCD display OK?
YES YES
END END
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Yes s Yes s
Change the Main board Change the Main board
NO NO
Change or charging the Change or charging the
Battery Battery
NO NO
Check open Pattern Check open Pattern
of power button of power button
Check Dome Sheet Check Dome Sheet
NO NO
Change the Main board Change the Main board
NO NO
Follow the LED trouble Follow the LED trouble
shoot shoot
NO NO
Follow the LCD trouble Follow the LCD trouble
shoot shoot
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