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This lesson talks about the earpiece fault repair

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In the first step, we use the resistance range of the multimeter to measure its resistance value

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Generally speaking,

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the resistance value of the earpiece is considered to be no problem between 20 ohms and 30 ohms

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If the measured resistance value is infinite,

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it means that the wire between the two pins inside the earpiece is broken.

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If the measured resistance value is 0, it means that there is a direct short circuit,

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and the earpiece is damaged

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Because we are measuring the resistance value

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It should be noted that if it supports stereo, it has dual speakers, such as Huawei P40 and Redmi K50

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The value of the earpiece will tend to be the same as the resistance of the speaker, about 8 ohms

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This is the first step, to determine whether there is a problem with the earpiece

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What should I do if the earpiece is damaged?

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Definitely replace it

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This is Huawei P40, we measured its resistance to be around 8.2 ohms

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There is no problem with a deviation of 1 ohm, and the earpiece is normal

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If there is no problem with the earpiece,

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we have to remove the mainboard to measure the ground value of the earpiece data cable

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Measured on the shrapnel of the earpiece

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The data line refers to here

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These two shrapnel go to touch the earpiece, they are connected to the small audio

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The top earpiece of Huawei P40 supports playing music

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We use a multimeter to measure the ground value here to judge

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whether there is any problem with the circuit from it to the small audio

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If it is a model that does not support stereo,

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measure the ground value to judge whether there is a problem with the channel from it to the large audio

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What if there is a problem with the ground value?

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The problem is nothing more than OL or 0

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We talked about how to analyze earlier, you can refer to

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Let's sum it up

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For the ground value OL, find the measurement point leading to the components

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connected in series between the chips

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If it is short-circuited to the ground value,

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find all the components between the measurement point and the ground wire,

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that is, the components with one end connected to the ground and the other end connected to the line

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That's all for this lesson