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This lesson continues with troubleshooting steps for microphone circuits

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When no abnormality is found in the above two steps, we will proceed to the third step

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The third step is to measure the power supply of the microphone

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The power supply of the general microphone is 2.6 volts

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Where does this voltage come from?

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It comes from Big Audio

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The microphones of some early models were still powered by 1.8 volts

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Therefore, the voltage of the microphone generally cannot be lower than 1.8 volts,

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and cannot exceed 3 volts

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When is the safest time to measure power supply?

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It is safest in the boot state

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Find the pin from the microphone to the power supply, click on the program,

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and put the microphone in the working state, such as clicking record

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When recording, if the voltage of the microphone cannot be measured,

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it is necessary to replace the large audio chip, or replace the power chip containing the large audio

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If the big audio doesn't work, it certainly doesn't output power to the microphone

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By the same token, if the working conditions of the big audio are not normal, it will not work

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When the big audio is not working, all the functions that the big audio is responsible for will be lost

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At this time, we will consider the big audio

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What should I do if the fault is still not resolved after performing all the above steps?

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At this time, it is necessary to replace the microphone, and find a microphone with the same pin position

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Because of the same pin position, its function is close to the pin definition and can be used directly

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Generally speaking, the damage to the microphone is relatively small,

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unless the corrosion of water is serious, because the power of the microphone is relatively small

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After performing the above steps, we turned on the test, and the microphone still had a fault

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Usually, it is necessary to re-solder the large audio or the power chip containing the large audio

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It depends on the platform, MediaTek's big audio is in the power chip

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If it doesn't work after re-soldering, you need to find the same type of chip to replace

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Step 6, after replacing the main audio, turn it on and test it

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If the microphone still fails, it means that both the main and auxiliary microphones are faulty

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At this time we have to consider the main audio

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First rule out the welding manual problem,

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remove the large audio or the power chip containing the large audio

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Measure the pins on the chip related to the sound circuit with respect to ground

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What is this step to judge?

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It is to judge whether there is any problem with the capacitance and inductance connected to the chip,

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or whether there is any abnormality in the channel from this pin to other chips

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For example, whether there is an open circuit or a short circuit from the large audio to the CPU

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Here are the troubleshooting steps for a microphone failure

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Generally, if we follow this procedure to repair, most of the microphone circuit can be solved

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Of course, there is a situation

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If you can record, but no matter whether you turn on the speakerphone or not when you make a call,

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the other party can't hear you, and you can't hear the other party's speech

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Then this is a problem with the baseband circuit, and generally has little to do with the main audio

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However, this phenomenon is very rare for Android phones

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The main audio is mainly responsible for the microphone,

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we need to judge the fault according to when and which microphone is enabled

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That's all for this lesson