Power On Trouble; Only For Training And Service Purposes - LG KE990 - Viewty Cell Phone 100 MB Service Manual

4. TROUBLE SHOOTING

4.6 Power on trouble

Power on sequence of KE990 is :
→ PM_ON_SW_N go to low (VA700, PM6635-2M KPDPWR_N pin#24) →
PWR key press
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?
Press PW R key
Keypad L ED on?
VA700 h igh to low
when key press?
VREG_MSMC_1.2V,
VREG_MSMP_2.7V, VREG_MSME
VREG_TCXO_2.85V,
VR EG_MSMA_2.6V
Power up?
Is c lock ok ?
X100 : 19.2M
X500 : 32.768Khz
Chang e th e Main board
LGE Internal Use Only
NO
Change or charging the
YES
NO
Follow the LED trouble
YES
NO
YES
NO
_1.8V
Chang e the Main board
YES
NO
YES
- 94 -
Batt ery
shoot
Check open Pattern
of power button
Check Dome Sheet
Check the TXCO and SLEEP CRYSTAL
Copyright © 2008 LG Electronics. Inc. All right reserved.

Only for training and service purposes