LG GS290 - Page 87

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Only for training and service purposes
4. TROUBLE SHOOTING
GS290 Operational Description Revision B
LG Electronics 88/136 LGE Property
4.12.1. Checking DCXO Circuit
Replace X500
No
Yes
DCXO Circuit is OK.
See next page to check
PLL
C
ir
cu
i
t.
TP1(C516) : 26MHz
Figur2. DCXO
DCXO Circuit Dia
g
ram
Figure 3. DCXO Cicuit
Waveform
Is the waveform
of TP1(C516) similar to Fig.4?
TP1 (C516)
X500
Figure 4. DCXO Waveform
Checkin
g
Points
Checkin
g
Flow
26MHz
X500 TSX-3225
21
3
4
GND2 HOT2
HOT1 GND1
U500
PMB6272
19
18
17
16
15
14
13
2
1
11 01
9
8 7 6
5 4
3 2 1
A
XA
B
XB
8V2
G
IDD
DV
A
D
K
L
C
5V
1GI
D
D
DV
3SYS
F
2SYSF
OX
X
OX
GND1
FSYS1
VDDXO2V8
EN
VDDVCO2V8
VCO_RC
VDDRX1V5
1nC516
C517
47n
R508
820
RF_EN
26MHZ_MCL
K
TP1(C516)