Samsung SGH-F490 Service Manual page 17

9. Flow Chart of Troubleshooting
9-1. Power On
' Power On ' does not work
Check the Battery Voltage
is more than 3.4V
U401 pin F10(PS_HOLD)
Check the Clock at
OSC400=32.768KHz
L400(VREG_MSMC)=1.2V?
C424(VREG_MSME)=1.8V?
C423(VREG_MSMP)=2.6V?
C422(VREG_MSMA)=2.6V?
C418(VREG_TCXO)=2.8V?
Check for the clock at C435
Check the initial operation
Yes
Yes
= 2.6V?
Yes
Yes
Yes
Yes
= 19.2MHz
Yes
Yes
END
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No
Change the Battery
No
Check the U401 related to PS_HOLD
No
Resolder OSC400
No
Check the U401
No
Check the U401
No
Check the clock generation circuit
(related to TCX100)
9-1