LG KM380t Service Manual page 87

6. Trouble shooting
6.13.1 FEM Circuit
√ Part Description of FEM
Application Mode
EGSM Tx
Rx
DCS1800 Tx
PCS1900 Rx
√ Check point of FEM
C522
47p
C523
47p
U502
LSHS-C085FB
11
LGE Internal Use Only
FEM Circuit
Check
Control signal of
FEM
YES
Check the next part
Fig 10 Debugging flowchart of FEM circuit
VC1
High
Low
Low
Low
R509
VC1
0
Control Signal of FEM
R590
VC2
0
Fig 11 FEM circuit (U502)
Replace
NO
PCB
VC2
Low
Low
High
Low
R509
R590
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U502
Only for training and service purposes