Checking Vc-Tcxo Block - LG U370 Service Manual

4. TROUBLE SHOOTING

4.4 Checking VC-TCXO Block

The reference frequency (19.2MHz) from X100 (VC-TCXO) is used in UMTS TX part, GSM part and
BB part.
TP1
RTR6275_TCXO
TP3
LGE Internal Use Only
Schematic of the VC-TCXO Block
DSA321SCE-19.2M
7
8
VREG_TCXO_2.85V
3
4
C169 C170
0.1uF 1000p
C172 100p
TCXO_PM
C174 1000p
TP3
Test Point of the VC-TCXO Block
TCXO
X100
19.2MHz
NC3 NC2
6
NC4 NC1
5
OUTPUT GND
2
100ohm R123
VCC VCONT TRK_LO_ADJ
1
R124 100K
VCC
5
C175 0.01u
2 4
U105
3
GND
TC7SH04FU
TP2
X100
Copyright © 2007 LG Electronics. Inc. All right reserved.
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TP2
C173
1000p
TCXO_BT
TP1
Only for training and service purposes