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iPhone audio circuit repairing

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This video mainly explains the working principle of hands-free and speaker circuit

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Block diagram fits iPhone 8 to iPhone 12 Pro Max models

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Let's first look at the block diagram of the working principle of the hands-free circuit

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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 simultaneously sends it to the earpiece power amplifier and the speaker power amplifier through the I2S bus

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If we don't press hands-free, the data is only sent to the earpiece amplifier

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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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The signal output by the earpiece amplifier will be connected to the earphone cable speaker

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The signal output from the speaker amplifier will be connected to the charge cable speaker

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At this time, the speaker will sound

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Let's look at the line that the audio signal takes when playing a song

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When we play the songs stored in the mobile phone,

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the CPU will read the audio data through the PCIE bus

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After the CPU reads the audio data, it will send the data to the big audio

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After receiving the data, the big audio encodes and decodes the data,

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and then sends it to the earpiece amplifier and the speaker amplifier through the I2S bus

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After the earpiece power amplifier and the speaker power amplifier receive the voice data,

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they will boost the voltage and load the voltage to the output terminal

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The high voltage output from the earpiece amplifier will connect to the earpiece stand speaker

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The audio signal output by the speaker amplifier will be connected to the charge cable speaker

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At this time, the speaker will sound

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When we play songs or there is no sound in the hands-free,

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we need to check the audio amplifier to the big audio,

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the big audio to the CPU and other lines

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A broken wire in the line, or a damaged connected component, will cause a silent failure

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That's all for this video