LG KG920 - Page 78

4. TROUBLE SHOOTING
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(2) Checking VCTCXO Circuit
X501.3
(OUT)
X501.4
(VCC)
X501
Check Pin 3.
Refer to Graph 4(b)
26 MHzO.K?
NoNo
VCTCXO Circuit is OK
See next Page to check
Mobile SW
VCTCXO Circuit is OK
See next Page to check
Mobile SW
Yes
Check Pin 4.
Refer to Graph
4
(a
)
2.75V OK?
No
Yes
Changing X500
Check U101, PMIC
(AFCDAC)
4
VCONT
1
26MHz
X501
2
GND
3
OUT
VCC
15K
R523
C548
1000p
2V75_VVCXO
C549
2.2u
AFC
Figure 4-6. Figure 4-7.
Figure 4-8.
TEST POINT
CIRCUIT
CHECKING FLOW
WAVEFORM
Graph 4-1.
Graph 4-2.