LG KG70c Service Manual page 42

KG70C
3.3.5. When Keytone and ring sound isn't heard. 3.3.5. When Keytone and ring sound isn't heard.
Please refer to the receiver part for circuit diagram and test point. Please refer to the receiver part for circuit diagram and test point.
• •
Circuit Diagram Circuit Diagram
U501 U501
START START
Receiver's Receiver's
wire soldering wire soldering
OK? OK?
When playing the ring sound or key tone When playing the ring sound or key tone
,is there square wave at C537, 538 ,is there square wave at C537, 538
Square wave Square wave
appear at pin #6 and pin #9 appear at pin #6 and pin #9
of U502 of U502
Change Receiver Change Receiver Change Receiver
C537, 538 C537, 538
Yes Yes
Yes Yes
No No
Yes Yes
C538 C538
C537 C537
No No
Solder again the RCV Solder again the RCV Solder again the RCV
No No
Check o r change the U502 Check o r change the U502 Check o r change the U502
41
Test Point Test Point
U502 U502
U501 U501
Figure 3-3-5 Figure 3-3-5
Change the U501 Change the U501 Change the U501