Checking Rf Rx Block - LG L602i Service Manual

Checking RF Rx Block

GSM 900 Rx
GSM 1800 Rx
GSM 1900 Rx
WCDMA 800
WCDMA 2100
L1018
8.2nH
L1019
47nH
EGSM.RX
C1029
1000p
L1022
47nH
L1024
8.2nH
925-960 MHz
Schematic of GSM/DCS/PCS Rx Block
Test Point (RF Rx Level)
LOW LOW HIGH
HIGH
OFF
LOW HIGH HIGH
LOW HIGH LOW
GSM_PA_BAND MODE
HIGH LOW HIGH
LOW GSM
HIGH HIGH HIGH DCS / PCS
HIGH
1930-1990 MHz
L1012
1.2nH
L1014
12nH
DCS.RX
C1022
1000p CP2_OUT
L1017
12nH
L1020
1.2nH
1805-1880 MHz
R1011
82
C1033
120p
Set the Phone Rx is ON
Check
soldering
YES
Check
FEM & buffer
YES
Change the board
- 93 -
4. TROUBLE SHOOTING
HIGH
L1003
1.2nH
L1004
5.6nH
PCS.RX
C1008
1000p
L1007
5.6nH
L1009
1.2nH
VREG_RFTX_2.85V
C1012
R1007
33p
1.8K
C1020
10n CP_HOLD2
29
CP2
30
VDDA9
31
UHF_LO_BUFF
RX_VCO_IN
R1010 32
R_BIAS
11.3K (1%) 33
GSM1800_INN
34
GSM1800_INP
35
VDDA10
36
GSM900_INP
37
GSM900_INN
38
VDDA11
39
TX_MOD_CP
40
VDDA12
41
TX_VCO_FB
R1014 42
C1034
47
1000p C1035
C1037 82p
22n (1%)
(PPS)
NO
Resoldering
NO
Change FEM & buffer
EGSM.RX
DCS.RX
PCS.RX
2.2uH
L1001
2.2uH
L1005
2.2uH
L1006
2.2uH
L1008
R1003
VREG_
10
C1010
0.1u
C1011
33p
C1013
33p
RX_IN RX_
14
RX_IP RX_
13
RX_
RX_QN
12
RX_
RX_QP
11
VDDA4
10
VCO_TUNE
9
RTR6250D VTUNE_REF
8
U1001 VDDA3
7
TCXO RTR6250
6
VDDA2
5 (1%)
VDDA1
4 R1012 3.3K
FAQ1
3
CP1
2
CP_HOLD1
1
C1036
0.01u