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The maintenance of iPhone startup constant current and current jump faults
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In this lesson, we will mainly explain the maintenance methods of these two faults
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Repair process step 3
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If the customer's mobile phone cannot be brushed,
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we can measure whether the resistance and voltage of the I2C bus are normal
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It is mainly used to eliminate problems such as short circuit
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or disconnection of the chip connected to the I2C bus
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Next, let me demonstrate the measurement of the I2C bus
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Let's take the iPhone 11 model as an example
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Let's first look for the I2C signal in the drawing
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If you don't know whether the result you search is right,
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you can open the information file under the iPhone catalog to check,
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6- 12 Promax I2C bus
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Find the model that needs to be tested,
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first observe all the I2C buses above,
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and then go to the drawing to find them one by one
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We look for the I2C bus in the drawing
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After searching, it is identified as ISP I2C,
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which is the I2C bus of the peripheral
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These are the main I2C buses
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We first measure the main I2C
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There are four groups here, from 0 to 3,
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and I2C4 at the bottom, a total of 5 groups
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These 5 groups of buses are the same as those marked in the block diagram
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After the main I2C bus is tested, we can test the SMC
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We click the logo at the end of the line, right-click to find the bitmap signal,
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it will automatically jump to the bitmap
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We can measure the diode value at the location of the yellow dot
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Next, we first measure this group
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The multimeter is adjusted to the diode level,
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the red marker is grounded,
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and the black marker is used to measure
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The measured value is about 300, which is normal
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Generally, the value of the I2C bus is between 300-450
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For each group of I2C, we need to measure
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Let's measure the resistor RC020 position
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The measured value is more than 300, indicating normal
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Let's measure I2C1
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The value is more than 300, which means it is normal
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Let's measure the next group, measure the RC031 position
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The value is more than 300, which means it is normal
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Let's measure I2C2, we need to measure the top resistor
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The value is more than 300
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The other is more than 300,
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which means that this group of I2C bus is no problem
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If the measured value is 0,
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it generally means that the chip or capacitor connected to the line is damaged
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Generally, we remove the capacitor first,
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and if the value is still 0 after removal
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If only the CPU is connected to this group of buses,
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it means that the CPU may be damaged
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If the value is relatively high or OL when measuring,
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it may be that the inductor of this line connection is broken
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Like this bus, it is connected to the CPU through the resistor R8156
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We can measure this end of the resistor,
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if it also shows OL
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That means it is disconnected to the CPU,
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we need to remove the CPU, and then add a flying wire
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If the value measured at the end of the resistor is more than 300,
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it means that the fuse resistor is broken
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Next, let's measure the voltage
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When measuring the I2C bus cvoltage, first turn on the power
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The multimeter is adjusted to the voltage level,
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the black marker is grounded, and the red marker is used to measure
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We measure the voltage where we measured the diode value
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Models before the 11 series, the voltage is 1.8V
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12 series models, some voltage is 1.2V
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The voltage values of the I2C buses are all around 1.77V,
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which means they are normal
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The normal diode value does not mean that the voltage is normal,
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so we also need to measure the voltage
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If the voltage is abnormal,
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it also means that the components connected to this line are damaged
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Ok, that's all for this video
