Samsung SGH-E720 Service Manual page 19

SGH-E720 Flow Chart of Troubleshooting
2-2-4. EGSM TX
NO
U106 Pin#9
About 2~3 dBm?
YES
C108,CN100,L103
Check & Change
C102
= 3.7V?
Level of U101
Pin #20 is
1.2V?
YES
U101 pin#11
About -5 dBm?
U101 pin#18
High ?
Change U101
U103 Check
Pin#9,32 ≥ 2.8V ?
U103 Check
Pin #8 : 13MHz ?
Vpp : 860mV?
NO
U103 Pin
#4,5,6,7 = 1.7V?
Change U101
Check U401
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U106
Pin#10 = High?
YES
Level of
NO
U106 Pin#7 is
4~5dBm ?
YES
U106
Check & Change
NO
Check the
Battery Block
YES
NO
U401 TXP OK ?
YES YES
NO
NO
Check U401
YES
NO
YES
OSC101 Check
NO
Pin #3 : 13MHz ?
Vpp : 950mV?
YES
YES
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NO
U401
Check & Change
Continuous TX ON condition
TX Power Code : 500 code Applied
NO
Check
Check & Change
U401,C418,100,130
Check or resolder
NO
YES
R112,C132
resolder
2-16
CH : 62
RBW : 100KHz
VBW : 100KHz
SPAN : 10MHz
REF. Level : 10dBm
ATT. : 20dB
U401
NO
OSC101 Check
Pin #4 = 2.8V ?
YES
OSC101
Change or resolder