LG F3000 Service Manual page 59

4. TROUBLESHOOTING
(1) Checking VCTCXO Circuit
TEST POINT
CIRCUIT
AFC
Waveform
Graph 4-6(a)
Checking Flow
Check Pin 3.
Refer to Graph 4-1(b)
Check Pin 4.
Refer to Graph 4 -1(a)
R510 10K
C529
1000p
- 60 -
Yes
26 MHzO.K?
No
Yes
2.75V OK?
No
Check U101
2V75_VVCXO
R746 0
26MHz
GND VCC
2 4
VCONT OUT
1 3
X500
C528
2.2u
Graph 4-6(b)
VCTCXO Circuit is OK VCTCXO Circuit is OK
See next Page to check See next Page to check
ANT SW & Mobile SW ANT SW & Mobile SW
Changing X500
(1608)