Checking Vctcxo Circuit - LG KE970 Service Manual

5.11.3 Checking VCTCXO Circuit

Checking Points
Pin : 2.7V
X401
Pin 3: 26MHz
VCTCXO Circuit Diagram
2V7_VCXO
R419
0
X401
3 1
OUT VCONT
4 2
VCC GND
C444
26MHz
1uF
R420
620
AFC
C442 C443
22p NA
Checking Flow
Is the waveform
of Pin3 similar to
Yes
Is the waveform
of Pin4 similar to
Yes
VCTCXO Circuit is OK.
See next page to check
PLL Circuit.
Waveform
Pin 4
Pin 3
- 95 -
5. Trouble shooting
No
Replace X401
No
Checking U203
(PMIC)