Checking Rf Rx Block - LG U250 Service Manual

4. TROUBLE SHOOTING

4.7.5 Checking RF Rx Block

TP1
L102
100nH
U500
19
VDD GSM900_RX1
GSM900_RX2
GSM1800_RX1
GSM1800_RX2
7
GND1 GSM1900_RX1
8
GND2 GSM1900_RX2
10
GND3 WCDMA2100
12
GND4
13
GND5 D5011 CTRL1
15
GND6 CTRL2
17
GND7
20
GND8
21
GND9 GSM900_TX
23
GND10 GSM18001900_TX
TP3
TP2
Rev.C
5
6
1
2
3
4
9
18
22
16
14
C110 C109
33p 33p
Rev.D
C124 L403
100p 1.5nH
L116
L115
10nH
18nH
Schematic of GSM900/DCS/PCS Rx Block
TP1. DCS RX INPUT
TP2. PCS RX INPUT
TP3. GSM RX INPUT
TP1
1K R100
ANT_SEL0
1K R101
ANT_SEL1
TP2
TP3
+VPWR
C123 C121
33u
0.01u
- 90 -
C439 5p
C105
DCS
NA
C440 5p
C442 5.6p
C116
PCS
NA
C443 5.6p
L405 2.7nH
C120
EGSM
L111
NA
5.6nH
L406 2.7nH
Rev.C
0.5p
C190
NA
C191