Checking Vctcxo Circuit - LG KP270 Service Manual

4.17.1 Checking VCTCXO Circuit

Check TP2
(V cc of X501)
= 2.85V ?
YES
Check
0V< TP3< 1.8V ?
YES
wave form
of TP1(C545) Similar to
wave form below?
YES
VCTCXO is Ok .
See the next page
C545 1000p
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
NO
Chec k U 202
NO
Chec k U 101
NO
Replac e X501
TP1
TP2
X501
DSA321SA_26MHZ
3 4
OUT
VDD
2 1
GND VCONT
26MHz
- 105 -
4. TROUBLE SHOOTING
2V85_VRF
2G_EN
2G_DATA
2G_CLK
R521
2G_BS 20
TP2
C561 C562
0.1u 1u
R523 10K
AFC
C555
0.01u
TP1
TP2
TP3
LGE Internal Use Only