Samsung SGH-T400, Service Manual

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5. Flow Chart of Troubleshooting and Circuit Diagrams
5-1 Power ON
Flow Chart of Troubleshooting and Circuit Diagrams 5-1
'POWER ON'does not work
Charge the Battery
Check the Battery Voltage
is more than 3.4V?
No
Yes
Yes
Check U300 and the path from +VBATT
to C305
The node
between D300 and C305 > 2.8 V ?
No
Yes
When the "END" key is pressed,
D314 pin 1> 3.4V ?
Replace the PBA
No
END
U301 pin 1, 2, 9 > 3.4V ? Check the circuit related to U301
No
Yes
Check the initial operation
U301 pin 10 = 2.5 V ? Check U301 and related circuit
No
Yes
Check for the clock signal at R103
Check the clock generation circuit
(related to U102 and Q100)
No
Yes
Yes