Samsung SGH-X640 Service Manual page 34

Flow Chart of Troubleshooting
6. Speaker Part(Melody)
Speaker does not work
Yes
No
U300 pin 5 = 2.85V?
Resolder or replace U300
Yes
No
Check the Clock signal at
Check the clock generation circuit
Pin 1 of U301 (13MHz)
(related to OSC100 and U301)
Yes
No
U301 pin 17,18 ≒ 1.8V?
Resolder U301
(When U301 operate)
Yes
No
HDC700 pin 40,42 Check the circuit related to
≒ 1.8V?
"SPK_P/SPK_N" signal
Yes
No
Is Speaker working? Change the Speaker
Yes
END
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