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Usage of multimeter

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In this video, we mainly explain how the multimeter measures the diode value

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The diode value refers to a value measured with the diode range of the multimeter to ground

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In maintenance, it is also called measuring resistance,

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measuring impedance, hitting value, etc.

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In fact, these all refer to the same operation

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Measuring the diode value can help us judge whether there is a short circuit or disconnection in the line,

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and can help us judge whether the chip is damaged

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It is an essential step in maintenance, and it accounts for 80% of the maintenance

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Diode value measurement procedure

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Step 1, insert the black marker of the multimeter into the common port,

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and insert the red marker into the red jack marked by the voltage resistance

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Step 2, the multimeter is adjusted to the diode range

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Step 3, power off the mainboard

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Step 4, the red marker of the multimeter should be grounded,

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and the black marker is used to measure

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Step 5, after the measurement, the screen will display the reading,

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we can just read it directly, it has no unit

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Step 6, if the measured value shows 000,

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it means that the line is short-circuited

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If it shows OL, it means that there may be a disconnection in the line

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If the measured value is not much different from that of a good mainboard,

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it means that the diode value of the line is normal

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Precautions for Measuring Diode Values with Multimeters

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When measuring, the markers cannot be reversed

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After reversed connection, the value will not be able to be measured,

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or the measured value will be abnormal

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When measuring, the multimeter may make a sound when the value is lower than 100

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A sound does not mean that the line is short circuited,

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we must look at the value,

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because some lines have very low diode values

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For example, iPhone X,

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the GPU power supply value is only 1,

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the multimeter will display 001 when we measure,

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and it will make a sound,

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which does not mean a short circuit, which is normal

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Let's measure it in the physical mainboard

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Insert the black marker of the multimeter into the COM port,

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insert the red marker into the V port,

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and adjust the multimeter to the diode level

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When the diode icon is displayed,

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it means that the multimeter is currently in the diode range

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The red marker is grounded, and the black marker is used to measure

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The measured value is 0.244

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Under normal circumstances, we directly read 224

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We can compare the measured value with a good mainboard,

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or compare it with the reference value given in Xinzhizao

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If the value is not much different, it means that the diode value is normal

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Let's measure the connector pins

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The value of this connector pin is 647

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If we measure the signal, the value is 0,

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it means that the line is short-circuited

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If there is a pin with a value during measurement, the measured value is OL,

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indicating that there is a disconnection on the mainboard

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When measuring, if the black marker is grounded and the red marker is used for measurement,

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the measured value will be too large, or the value cannot be measured

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Ok, that's all for this video