LG KG270 Service Manual - Page 47
Test Point, Circuit, Waveform, Checking Flow
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4. TROUBLE SHOOTING RX Trouble (1) Checking VCTCXO Circuit TEST POINT SW400 U400 FL400 FL401 CHECKING FLOW Is the waveform of Pin3 similar to DCXO(X101) Waveform? Yes DCXO Circuit is OK. See next page to check PLL Circuit. No Replace X101 X101 U102 26MHz HOT1 1 GND2 4 CIRCUIT X101 NX3225SA 2V8_VIO Waveform Waveform Pin 2 Pin 1 3 HOT2 2 GND1 ( NX3225SA(W-188-34-7) R107 NA - 48 -
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4. TROUBLE SHOOTING
- 48 -
RX Trouble
(1) Checking VCTCXO Circuit
U400
SW400
U102
FL400
X101
FL401
Is the waveform
of Pin3 similar to
DCXO(X101)
Waveform?
Replace
X101
Yes
No
DCXO Circuit is OK.
See next page to check
PLL Circuit.
( NX3225SA(W-188-34-7)
2
GND1
GND2
4
1
HOT1
HOT2
3
NX3225SA
X101
26MHz
TEST POINT
CIRCUIT
Waveform
Pin 2
Pin 1
Waveform
CHECKING FLOW