LG -E400f Service Manual page 103

4.18.5 Headset micr ophone
MIC Signal: 3.5 pi Headset (CN701) → FB704 → R714 (TP4) MIC of MAX14579E & C09 (TP3) MICP of MSM75A
MIC Bias : VREG_MSME_1.8V → R713 (TP1) DET → R715 DET_IN → Headset MIC
HS Detect IC Bias: VREG_P3_.85V → C78 (TP2)
R713(TP1) is about 1.8V?
Make a some sound or voice to MIC
Some sound signal appears at
Some sound signal appears at
LGE Internal Use Only
START
Make a call
Yes
R714 (TP4)?
Yes
C09 (TP3)?
Yes
Work Well?
Yes
END
No
C78(TP) is about .85V?
No
Change the U700 (MAX14579E) or
Change the Main PCB
No
Change the Headset or Re-solder/
Change the CN701 or
Change the Main PDB
No
Change the U00 (MSM75A) or
Change the Main PCB
- 103 - Copyright © 01 LG Electronics. Inc. All right reserved.
4. TROUBLE SHOOTING
Only for training and service purposes