LG ID2750 Service Manual page 41

4.2.2 Check VCTCXO Circuit
TEST POINT Checking Flow
X100
U407 Pin4 (
+2.8V_TCXO) YES
Pin 3
VCTCXO Circuit is OK
19.2MHz OK?
See next page to check
SBI control signal
NO
YES
Pin4
Replace U407
2.8V OK?
NO
U407 Pin3
Check U400
(TCXO)
Circuit Diagram
Waveform
U407 Pin4 +2.8V_TCXO
U407 Pin3 TCXO