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iPhone audio circuit repairing

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In this lesson we're going to learn how to find the I2S audio bus from the CPU to the baseband

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of the iPhone 12 Pro Max

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After the bus has a problem, it will cause no handset and no transmission failure

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Search method step 1, find the baseband chip in the component map and confirm the position number

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Step 2, search for the position number in the circuit diagram

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Step 3, after finding the baseband, check the pins

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I2S is the audio bus from the CPU to the baseband when making a call

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Step 4, jump to the bitmap according to the pin, and view the connected components

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The diode value can be measured at the position of the yellow point in the bitmap

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When checking the maps, first open the iPhone 12 Pro Max component map, circuit diagram, and bitmap

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Find the baseband chip in the component map and confirm the position number

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Then search for the position number in the schematic diagram

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Because the baseband has many solder points,

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to prevent mistakes when searching, we click Advanced Search

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After clicking Advanced Search, there will be a list about the pages of the baseband chip

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Let's view them in turn

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In the list, the pin of the baseband chip marked with I2S represents the audio bus from the CPU to the baseband

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Pin AF30 of the baseband chip is the detection clock

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Jump to the bitmap according to the name,

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the detection clock is connected to the CPU through the middle connection point

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Pin AF32 is the data output of the I2S bus

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Jump to the bitmap according to the name,

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the data output pin is connected to the CPU through the middle connection point

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Pin AG31 of the baseband chip is the data input

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Jump to the bitmap,

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the pin is connected to the CPU through the middle connection point

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Pin AH30 is the serial clock of the I2S bus

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Jump to the bitmap according to the name,

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the serial clock is connected to the CPU through the middle connection point

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If there is no handset and no call failure after the iPhone is dropped,

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it is mostly because the I2S bus between the baseband and the CPU is disconnected

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We can measure the diode value of the I2S bus

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If the value is normal, we only need to reball the tin to fix the failure of no transmission and no handset

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That's all for this video