LG P705 - Page 105

4. TROUBLE SHOOTING
- 105 -
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Only for training and service purposes
LGE Internal Use Only
4.19.6 Headset micr ophone
MIC Signal: 3.5 pi Headset (J900) → FB710(TP4) → C213(TP4) EAR_MIC(MIC2P) of MSM7227A-1-AA
MIC Bias : VREG_MSME_1.8V → R722 (TP1) (DET) → R723(TP3)(RES) -> Headset MIC
HS Detect IC Bias: VREG_P3_2.85V
No
START
Make a call
Yes
No
Make a some sound or voice to MIC
Yes
R722(TP1) is about 1.8V & C751(TP2)
is about 2.85V?
R723(TP3) is about 1.2~1.4V?
Some sound signal appears at
FB710(TP4)
No
Some sound signal appears
at C213(TP5)
Change the U200(MSM7227A-1-AA) or
Change the Main PCB.
No
Yes
Change the Headset or Re-solder/
change the J900.
Yes
Re-contact or test the new Upper
FPCB.(If It’s OK, change the FPCB)
Change the Main PCB.
Change the U705(MAX14579E) or
change the Main PCB.