LG KG70c Service Manual page 22

KG70C
3.1.3 Checking VCTCXO Circuit 3.1.3 Checking VCTCXO Circuit
Test Point Test Point
Pin#3 Pin#3
Pin#4 Pin#4
Circuit Diagram Circuit Diagram
Waveform Waveform
Graph 3-1-1(a) Graph 3-1-1(a)
Check U101 Pin#3 Check U101 Pin#3
◆ Refer to Graph 3-1-1(a) ◆ Refer to Graph 3-1-1(a)
U101 U101
Check U101 Pin# 4 Check U101 Pin# 4
◆ Refer to Graph 3-1-1(b) ◆ Refer to Graph 3-1-1(b)
Figure 3-1-3 Figure 3-1-3
Checking Flow Checking Flow
19.2MHz OK? 19.2MHz OK?
No No
+2.9V_TCXO OK? +2.9V_TCXO OK?
No No
Check U401 Check U401
21
VCTCXO Circuit is Ok VCTCXO Circuit is Ok
Yes Yes
See next Page to check See next Page to check
Duplexer Duplexer
Yes Yes
Changing U101 Changing U101
Graph 3-1-1(b) Graph 3-1-1(b)