Checking Vctcxo Circuit - LG KF510C Service Manual

5. Trouble shooting

5.12.1 Checking VCTCXO Circuit

TP1(C453) : 2.85V
TP2(C441) : 26MHz
14
GND1
13
C441
1000p
TP2
LGE Internal Use Only
of TP2(C453) Similar to Fig.6?
X400
2V85_VRF
R410
10
R412
X400
10K
3 1
OUT VCONT
C442
4 2
0.01u
VCC GND
C452 C453
26MHz
0.1u 1u
TP1
Is the wavefor m
Yes
Is the waveform
of TP1(C441) si mil ar to Fig .6?
Yes
VCTCXO Circuit is OK.
See next page to ch eck
PLL Circuit .
TP1 (C453)
AFC
TP2 (C441)
Copyright © 2008 LG Electronics. Inc. All right reserved.
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No
Replace X401
No Checkin g U203
(PMIC)
Only for training and service purposes