Samsung SGH-X640 Service Manual page 27

2. Initial
R200 (RSTON) ="H"?
(memory CE) OK?
Check the circuit around
LCD & U304 (Short or not solder)
Initial Failure
Yes
Yes
Is U304 pin 4,6
Yes
Yes
END
SAMSUNG Proprietary-Contents may change without notice
This Document can not be used without Samsung's authorization
No
Check the circuit related to reset
No
7-3
Flow Chart of Troubleshooting
Check the U304