LG GX500 - Page 94

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4. TROUBLE SHOOTING
GX500 Operational Description Revision A
LG Electronics 95/143 LGE Property
Figure 4-30. DCXO (SIM1)
Waveform
Figure 4-33. DCXO Waveform
Replace
X406/X502
N0
Yes
X
-
T
AL Circuit is OK.
See next page to check
PLL Circuit.
Is the waveform
of TP similar to Fig.7?
TP1
(
C406
)
: 26MHz
X401
X502
Fi
g
ure 4-31. DCXO
(
SIM2
)
TP1
TP1 (C406)
Fi
g
ure 4-32. DCXO Cicuit(SIM1)
*SIM2-> Transceiver is embeded in BB chi
p
.
4.12.1 Checking DCXO Circuit
Checking Points
DCXO Circuit Diagram
Checking Flow
P
0
001
604C
20
19
18
17
16
15
14
13
1221
2211
3201
3SYSF 3X
R
2SYS
F X
4X
R
OX
4X
R
XOX 5V1A
N
LD
DV
GND1
FSYS1
VDDXO2V8
EN
VDDVCO2V8
VCO_RC
VDDRX1V5
VDDRX2V8
R402
820
26MHz
DSX321SG-26M
X401
21
34
9
14
C
N74
0.1U
26MHZ_MCLK
RF_EN
TP1