LG GX500 - Page 101

- 102 -
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Only for training and service purposes
4. TROUBLE SHOOTING
GX500 Operational Description Revision A
LG Electronics 102/143 LGE Property
4.13.3 Checking TX I/Q Signals
Checking Points
Figure 4-47. TX I/Q
I
Q
I
Q
Figure 4-48. TX I/Q Waveform
TX
*SIM2-> Transceiver is embeded in BB chip.
Figure 4-46. TX I/Q Circuit
Check
T
X I/Q signals TP
Signals are
Normal?
Replace Transceiver
PMB6272(U401)
Yes
No
T
X Part is OK.
Check Base Band Circuit
or
Re
-
Download
S/W and Cal
TP402
(
I
)
TP1
(
IX
)
TP2
(Q
X
TP401
(Q)
Checking Flow
TP402(I)
TP2(
Q
X
TP1(IX)
TP401(Q)
U401
3.3p
C421
n51
104L
2.7p
C431
2.7p
C427
TP401
TP402
FRV
_
5V1
2
7
26BMP
1
04
U
20
19
18
17
16
15
14
13
1221 2211
3201 429
528 627
726 825
924 033
132 231
33
34
35
36
37
38
39
40
41
GND4
GND3
VDDMIX2V8
VDDTX2V8
TX2
TX1
VDDTX1V5
VBIAS
FE2
A 1EF
XA 8V2SAIB
D
DV
B X
1X
R
XB 1XR
8V2G
I
DDDV X2XR
A
D
2X
R
KL
C
2
D
N
G
5V1GID
D
DV X3XR
3SYSF 3X
R
2SYSF X4X
R
OX 4XR
XOX 5V1A
N
LDDV
GND1
FSYS1
VDDXO2V8
EN
VDDVCO2V8
VCO_RC
VDDRX1V5
VDDRX2V8
C407
0.1U
F
R
V
_
5
V
1
C408
2.2P4.7P
C409
FRV_5V1
3.3p
C426
0.1U
C411
C412
4.7P
220N
C413
R401
10
R402
820
C416
0.1U
26MHz
DSX321SG-26M
X401
21
34
FRV_58V2
9
14
C
N
7
4
4.7N
C423
FRV_58V2
FRV_
58
V
2
0.1U
C430
F
RV_
5
8V2
0.22U
C432
FRV_58V2
2.2P
C435
HN1.5
804L
R405
10
504L
HN51
n7.4
204L
C438
0.1U
0.1U
C442
I
IX
Q
QX
FE2
FE1
RF_DA
RF_CLK
LBAND_PAM_IN
HBAND_PAM_IN
GSM900 PCS1900GSM850
DCS1800
TP2(QX)TP1(IX)
TP401(Q)
TP402(I)