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This lesson continues with speaker fault repair

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Step 6, if no abnormalities are found in the above 5 steps and no problems are found in the measurement,

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we will proceed to the sixth step

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Resolder the small audio chip

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Of course, in the case of weak soldering of the audio chip

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In the maintenance of these mobile phones, we found that adding soldering does not actually have much effect

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Generally, the solution is to replace the ringtone amplifier chip

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It may be that the chip is damaged and the drive signal of the speaker cannot be output

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At this time, you need to know which is the small audio chip

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It can be deduced which is the small audio frequency through the model or its circuit structure.

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If the small audio chip is replaced, the speaker still has no sound,

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we need to remove the chip to measure the chip reset signal, interrupt signal,

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I2C bus and I2S bus ground value

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What is the judgment of ground value?

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Because the reset leads to the CPU, the purpose of measuring the ground value is to judge

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whether there is a short circuit or an open circuit on the line from it to the CPU

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The interrupt signal is also to the CPU, and the I2C bus is also to the CPU

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We will not talk about the analysis method of open circuit and short circuit here,

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because many circuits have been discussed before.

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If you want to measure, you must first be able to understand the drawings

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If you can't understand the drawings, there is nothing you can do. Just hand it over to your peers

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After removing the chip, we will measure on these pins,

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and measure the ground value of its corresponding reset signal, interrupt signal, etc.

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The above is to judge the problem around the driver chip of the speaker

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and the circuit of the two components of the speaker

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But we should pay attention, the above is only for the speaker without sound

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If you turn on the hands-free when making a call, the speaker has no sound,

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but there is sound when playing music, you must take into account the large audio circuit

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Because it drives the earpiece, the driver must work when processing the microphone signal

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In another case, if there is only sound in the settings,

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and there is no sound from the speaker and earpiece in other cases,

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it is necessary to consider whether the phone has entered the headphone mode.

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What if it's headphone mode?

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To see which chip and circuit is responsible for the headphone detection signal, just focus on finding the line

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Let's sum it up

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When repairing the sound circuit, all the functions of the microphone are tested,

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and the functions of the earpiece and speaker are tested.

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Why do you want to do this? Do you want to test the functions that other components are responsible for?

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Because the microphone is also a sound circuit

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By testing the function of the microphone and the working status of the earpiece speaker,

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we can comprehensively judge whether there is a problem with the large audio or the small audio,

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or both of them, or the problem of the baseband circuit.

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That's all for this lesson