LG GX500 Service Manual page 94

GX500 Operational Description
4.12.1 Checking DCXO Circuit
Checking Points
X401
TP1(C406) : 26MHz
Figure 4-30. DCXO (SIM1)
X502
Figure 4-31. DCXO (SIM2)
Checking Flow
Is the waveform
of TP similar to Fig.7?
Yes
X-TAL Circuit is OK.
See next page to check
PLL Circuit.
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DCXO Circuit Diagram
VDDRX2V8
20
VDDRX1V5
R402
19
VCO_RC
820
18
VDDVCO2V8
17
EN
16
VDDXO2V8
15
FSYS1
14
GND1
13
DSX321SG-26M
Figure 4-32. DCXO Cicuit(SIM1)
*SIM2-> Transceiver is embeded in BB chip.
N0
Replace
X406/X502
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4. TROUBLE SHOOTING
0.1U
RF_EN
26MHZ_MCLK
TP1
X401
4 3
1 2
26MHz
Waveform
TP1 (C406)
Figure 4-33. DCXO Waveform
Revision A
TP1
LGE Internal Use Only
LGE Property