Egsm Transmitter - Samsung SGH-E715 Service Manual

9. EGSM Transmitter

F400 Pin#6
About 2~3 dBm?
YES
C402,CN400
Check & Change
C403
= 3.7V?
YES
Level of
U400 Pin #6 is
1.2V?
YES
YES
U400 pin#7
About -5 dBm?
NO
U400 pin#3
High ?
YES
Change U400
U401 Check
Pin#9,32 ≥ 2.8V ?
U401 Check
Pin #8 : 13MHz ?
Vpp : 860mV?
NO
U401 Pin
#4,5,6,7 = 1.7V?
Check U300 Change U400
SGH-E715 Flow Chart of Troubleshooting and Circuit Diagrams
NO
F400
Pin#10 = High?
YES
NO
Level of
F400 Pin#7 is
4~5dBm ?
YES
F400
Check & Change
NO
Check the
Battery Block
NO
Check
& Change R406
OK ?
YES
NO
Check U300
NO
YES
OSC400 Check
NO
Pin #8 : 13MHz ?
Vpp : 950mV?
YES
YES
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NO
U300,301
Check & Change
Continuous TX ON condition
TX Power Code : 500 code Applied
NO
Check & Change
U100,C106,C112
Check or resolder
NO
YES
R412,C426
resolder
2-11
CH : 62
RBW : 100KHz
VBW : 100KHz
SPAN : 10MHz
REF. Level : 10dBm
ATT. : 20dB
U300
NO
OSC400 Check
Pin #4 = 2.8V ?
YES
OSC400
Change or resolder