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iPhone audio circuit repairing

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This video mainly talks about the working principle of the earpiece circuit

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Earpiece circuit works the same on iPhone 8 to iPhone 12 Pro Max models

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Working principle step 1, when the call is connected,

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the baseband will send the voice data of the other party's call to the CPU through the I2S bus

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Step 2, the CPU will send the digital voice signal to the big audio

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Step 3, the big audio processes the digital voice signal sent by the CPU,

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and sends it to the earpiece power amplifier through the PDM bus

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Step 4, after the earpiece power amplifier recognizes the voice data,

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it will not boost the voltage, it will convert through the internal circuit,

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and directly load the voice data to the output terminal

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At this time, the speaker of the earpiece can produce sound

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Because there is no boost in the earpiece amplifier,

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the sound from the earpiece speaker is relatively small.

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If we can't hear the other party's voice when answering the phone,

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it means that there may be a problem with the entire line from the handset connector to the baseband,

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and we need to check step by step

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That's all for this video