LG CU405 Service Manual page 78

4.5.1 Checking Ant. SW Module
Refer to chapter 3.3
ANT100 SW100
L90
ANT
6.8p
KMS-507
VREG_RF_2.85V
ANT_SEL0
ANT_SEL1
ANT_SEL2
ANT_SEL3
ANTENNA SWITCH MODULE LOGIC
LMSP4LMA-573TEMP_Rev B Later
ANT_SEL0
GSM900/GSM850 TX HIGH
DCS/PCS TX HIGH
GSM 850 RX LOW
GSM900 RX LOW
DCS RX LOW
PCS RX LOW
UMTS 850 HIGH
UMTS 1900 HIGH
TP3
Schematic of RF Tx level
C80 56p
G2
RF
G1
TP1
15nH L106
C86 C87
0.1u 33p
1K R100
1K R101
1K R102
1K R103
ANT_SEL1 ANT_SEL2 ANT_SEL3
HIGH LOW LOW
LOW LOW LOW
LOW LOW LOW
LOW HIGH LOW
HIGH HIGH LOW
HIGH LOW LOW
LOW HIGH LOW
LOW HIGH HIGH
4. TROUBLE SHOOTING
TP1
TP2
TP2
14 1
VC1 GSM1800RX1
13 2
VC2 GSM1800RX2
12 3
VC3 GSM1900RX1
11 4
VC4 GSM1900RX2
5
GSM900RX1
10 6
VDD GSM900RX2
7
GSM850RX1
9 8
GND1 GSM850RX2
18
GND2
C88
20 15
GND3 U100 UMTS1
21 16
GND4 UMTS2
23
GND5
24 22
GND6 GSM1800_1900TX
26 25
GND7 GSM850_900TX
27
GND8
28 17
GND9 NC
L111
56p
LMSP4LMA-573TEMP
TP3
C101
1.2p
4.7nH
L120
L121
NA
L122
15nH
14
DCS_PCS_OUT DCS_PCS_IN
GND5 BS
NA
L123 GND4 TX_EN
11
U102
VCC VBATT
TQM7M5003
GND3 GND1
GND2 VRAMP
8
GSM_OUT GSM_IN
- 79 -
L109
56p
WCDMA_850
1.8nH
L112
WCDMA_1900
1.5nH
1 R108
82
2
GSM_PA_BAND
11.4dB
3
GSM_PA_EN
4
5
6
7 5
RFOUT
R114
GSM_PA_RAMP
2.2K