LG GT350 Service Manual page 89

4. TROUBLE SHOOTING
4.12.1 Checking DCXO Circuit
Checking Points
TP1(C616) : 26MHz
Figur2. DCXO
DCXO Circuit Diagram
VCO_RC
18
VDDVCO2V8
17
EN
16
VDDXO2V8
15
FSYS1
14
GND1
13
R612
820
X601 TSX-3225
4
3
GND2 HOT2
1 2
HOT1 GND1
26MHZ
Figure 3. DCXO Cicuit
LGE Internal Use Only
Checking Flow
RF_EN
C616 0.001uF
26MHZ_MCLK
C617
0.047uF
TP1
TP1
Is the waveform
of TP1(C616) similar to Fig.4?
Yes
DCXO Circuit is OK.
See next page to check
PLL Circuit.
Waveform
TP1 (C616)
Figure 4. DCXO Waveform
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No
Replace
X601
Only for training and service purposes