Checking Rf Rx Block - LG CU405 Service Manual

4. TROUBLE SHOOTING

4.5.3 Checking RF Rx Block

TP1. GSM850 Rx Input
TP2. GSM900 Rx Input
TP3. PCS Rx Input
TP4. DCS Rx Input
1
GSM1800RX1
2
GSM1800RX2
3
GSM1900RX1
4
GSM1900RX2
5
GSM900RX1
6
GSM900RX2
7
GSM850RX1
8
GSM850RX2
L109
C88 56p
15
00 UMTS1
16
1.8nH
UMTS2
22
SM1800_1900TX
25
GSM850_900TX
17
NC
L111
56p
MA-573TEMP
C101
1.2p
4.7nH
L120
NA
L122
14 1
DCS_PCS_OUT DCS_PCS_IN
2
GND5 BS GSM_PA_BAND
3
GND4 TX_EN GSM_PA_EN
11 4
LGE Internal Use Only
TP4
TP4
TP3
WCDMA_850
L112
WCDMA_1900
1.5nH
TP1
+VPWR
R108
DCS_PCS_TX
82
11.4dB
Schematic of GSM850/GSM900/DCS/PCS Rx Block
TP2 TP1
TP3
L100 4.7nH
L101
NA
12nH
L102
L104 4.7nH
L105 5.1nH
L107
12nH
L108 5.1nH
L110 22nH
NA
L113
L114
56nH
L115 22nH
L116 27nH
47nH L117
L118 47nH
L119 27nH
TP2
Copyright © 2007 LG Electronics. Inc. All right reserved.
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55
ENV_OUT
46
WCDMA_1900_TX_OUT HB_RF_OUT
C89 6p
44
DCS_PCS_TX HB_RF_OUT
C90 6p
43
GSM_TX LB_RF_OUT
C93 5p
42
WCDMA_850_TX_OUT LB_RF_OUT
C94 12p
24
TX_ON RF_ON
56
TX_AGC_ADJ VCONTROL
54
DAC_REF DAC_REF
C99
14
12p SBDT
(1%)
R104 12K
3
R_BIAS1
27
R_BIAS2
R105 680 (1%)
SSBDT_RTR
31
GCELL_INP
30
GCELL_INN
32
EGSM_INP
33
EGSM_INN
38
DCS_INP
39
DCS_INN
36
GPCS_INP
37
GPCS_INN
22
CAL_INP
23
CAL_INN
26
WLNA_IN
Only for training and service purposes