the other party can not hear

Failure Analysis:
As the mobile phone transmitter (microphone) and the PCB connection between the use of almost all non-permanent mechanical connection, a relatively small area of reed contacts, coupled with cell phones are for use in outdoor mobile products, and therefore prone to poor contact transmitter failure.
Examination and treatment:
(1) The transmitter is being exposed? Approach: correction or clean spring.
(2) electret microphone static DC bias voltage is normal? (Typically 1.5 ~ 2V)
(3) The transmitter quality. Can be used with the table number three 20kΩ resistor in the power of file down the measurement. When the close-talking and not talk Duizhehuatong, the normal resistance of the microphone of its ends should be significant changes. If little or no variation, then the microphone poor quality or damaged. Another way is to check: In the call state, with an oscilloscope or AC-3 files with the table measure the voltage across the microphone, if the voltage is normally the problem is illustrated in the back of the voice processing section.
(4) BB processing IC CITIC source in part (such as: programmable audio pre-amplifier, A / D converter) whether it is a problem. Typical operating voltage failure is incorrect or the relevant part of the many cold solder joint.
(5) The microphone hole is blocked?

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