LG KT520 Service Manual page 104

Connect the phone to network
Equipment and setup call
Setup 1KHz tone out
1 Does the sine wave appear
Does the sine wave appear
2
Does the sine wave appear
3
Does the sine wave appear
4
5
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Only for training and service purposes
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at C639,C640?
YES
at U601 ?
YES
at C643,C644 ?
YES
At R501,R502?
YES
Can you hear sine wave
out of a speaker ?
YES
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4. TROUBLE SHOOTING
NO
Change the main board
The sine wave not appear
NO
Change the U601
NO
Change the main board
NO
Change the main board
NO
Change each Speaker
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