LG PRADA KE850 - Page 101

5. Trouble shooting
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5.13.5 Checking Mobile SW & FEM
Mobile SW & FEM Circuit Diagram
RX Mode EGSM DCS PCS
ANT_SW1 Off Off Off
ANT_SW2 On Off Off
ANT_SW3 Off On Off
Checking Points
SW401
C401
R436 (ANT SW2)
R435 (ANT SW3)
U401
R437 (ANT SW1)
Front End Module
0.1u
C405
VRF2V85
0
R403
C419
6
TX1G
8
TX2G
22
VCTRL1
VCTRL2
21
VCTRL3
20
VDD
3
EGSM_RX-
16
GMS_RX-
18
GND1
2
GND10
25 26
GND11
GND2
4
5
GND3
GND4
7
9
GND5
GND6
10
GND7
11 23
GND8 GND9
24
19
GSM_RX+
13
PCS_RX+
PCS_RX-
12
U401
YGHF-S006A
ANT
1
15
DCS_RX+
DCS_RX-
14
17
EGSM_RX+
Figure 10. Mobile SW & FEM Circuit
Figure 11. Mobile SW & FEM
Table 2. FEM RX Control Logic