LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
- 105 -
4.16 Speaker phone path
MSM6245 LINE_P,LINE_N
→
C405,C406, R408,R410
→
Audio AMP(U403)
→
Analog Switch(U401)
→
Speaker
Start
Connect the phone to network
Equipment and setup call Setup
1KHz tone out and insert
headset
Can you hear the tone?
NO
YES
END
Change the Main board
Sine wave appears
at C405,C406 and
R408,R410
YES
SPK_AMP_EN is 2.6V
YES
* Pulse signal appears at
SPK+ , SPK -
YES
* Pulse signal appears at
, SPK_RCV- ?
NO
NO
Change the Main Board
NO
Change the Main Board
NO
Change audio amp( U401)
YES
Change Speaker
* U370 use Class-D Amplifier.
So, The Output Signal of Amplifier was seen
Rectangular Pulse wave not sine wave.
When you inspect Main board.
Donít be cofused about that.
It was characteristic of Class-D Amplifier.
Summary of Contents for U370
Page 1: ...Date January 2008 Issue 1 0 Service Manual Model U370 Service Manual U370 ...
Page 178: ...Note ...
Page 179: ...Note ...