LG M6100 Service Manual - Page 65
Checking VCTCXO Circuit
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4. TROUBLE SHOOTING (1) Checking VCTCXO Circuit TEST POINT Checking Flow Check Pin 3. Refer to Graph 4-1(b) Check Pin 4. Refer to Graph 4-1(a) Yes 13 MHzO.K? No 2.75V OK? Yes No Check U101 VCTCXO Circuit is OK See next Page to check ANT SW & Mobile SW Changing X501 CIRCUIT AFC R507 10K C533 1000p X501 2 GND VCC 4 VCONT OUT 1 3 13MHz 2V75_VVCXO C532 2.2u (1608) Waveform Graph 4-6(a) - 66 - Graph 4-6(b)
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(1) Checking VCTCXO Circuit
4. TROUBLE SHOOTING
- 66 -
Check Pin 3.
Refer to Graph 4-1(b)
13 MHzO.K?
No
No
VCTCXO Circuit is OK
See next Page to check
ANT SW & Mobile SW
VCTCXO Circuit is OK
See next Page to check
ANT SW & Mobile SW
Yes
Check Pin 4.
Refer to Graph 4-1(a)
2.75V OK?
No
Yes
Changing X501
Check U101
(1608)
10K
R507
2V75_VVCXO
C533
1000p
C532
2.2u
13MHz
X501
2
GND
3
OUT
4
VCC
1
VCONT
AFC
TEST POINT
CIRCUIT
Waveform
Checking Flow
Graph 4-6(a)
Graph 4-6(b)