6
11
GSM1800_1900TX
GSM1900RX1
7
8
GSM1900RX2
1
GSM850RX1
GSM850RX2
2
GSM850_900TX
13
3
GSM900RX1
GSM900RX2
4
19
NC1
20
NC2
16
VC1
VC2
10
LMSP43NA-782
U502
17
ANT
GND1
9
GND2
12
14
GND3
GND4
15
GND5
18
5
GSM1800RX1
GSM1800RX2
C502
0.01u
1
R501
1
R502
33p
C501
VC2
VC1
- 100 -
LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
5. TROUBLE SHOOTING
5.13.2 FEM Circuit
Fig 10 Debugging flowchart of FEM circuit
9
Part Description of FEM
Application
Mode
VC1(TP1)
VC2(TP2)
Tx High Low
EGSM
Rx Low Low
Tx Low High
DCS1800
PCS1900
Rx Low Low
9
Check point of FEM
Fig 11 FEM circuit (U501)
FEM Circuit
Check the next part
Check
Control signal of
FEM(TP1&TP2)
Replace
PCB
NO
YES
Control Signal
of FEM
TP1
TP2
U501
TP1
TP2