LG GD910 - Page 87

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Only for training and service purposes
5. Trouble shooting
GD910 service manual
waveform
of TP1(C443) Similar to
waveform below?
Check TP2
(
V
cc of X400)
=2.85V ?
Check U200
Chec
k
0V<TP3<1.8V ?
NO
Y
ES
NO
Check U101
Y
ES
NO
Replace X400
Y
ES
V
CTCXO is Ok.
See the next page
waveform
waveform below?
(
V
cc
Chec
k
0V<TP3<1.8V ?
NO
Y
ES
NO
Y
ES
NO
Y
ES
V
CTCXO is Ok.
See the next page
TP1
TP3
TP2
.
.
.
Waveform Waveform
V
CTCXO Circuit Dia
g
ram
V
CTCXO Circuit Dia
g
ram
Checking Flow Checking Points
GD910 service manual
5.14.1 Checking VCTCXO Circuit
.
.
.
2.2n
C506
2V85_VTCXO
0.1u
C447
2
GND
5
NC1_GND1
6
NC2_GND2
OUT
3
1
VC
4
VCC
TG-5021BA
X400
26MHz
R410
10K
R407 20
C446
1u
2
R
1
FB2
1000 pFC443
10n
C452
100KR426
2G_BS
2G_EN
2G_DATA
2G_CLK
TP1
TP2
TP3