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Recognition and Measurement of Electronic Components
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This video mainly explains how to judge whether the crystal oscillator is good or bad and how to replace it
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We understand that damage to the crystal oscillator will lead to various failures,
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so how do we judge whether the crystal oscillator is good or bad?
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First of all, the first method, after the mainboard is powered on,
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we use an oscilloscope to measure the crystal oscillator pins
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When the measured crystal oscillator frequency waveform has no clutter,
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and the frequency is consistent with the marked value,
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it means that the crystal oscillator is normal
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If the crystal oscillator has clutter or the frequency is abnormal,
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it means that the crystal oscillator is damaged
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The second method is to use the diode range of a multimeter
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to measure the two ends of the crystal oscillator
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If the value shows OL, it means that the crystal oscillator is normal
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If it shows a value, it means that the crystal oscillator is damaged
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The situation like this can only be roughly judged,
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and cannot be guaranteed to be 100% accurate
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The third method,
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we measure the voltage value of the two pins of the crystal oscillator
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The voltage of the two pins is about 0.8V,
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and there will be a voltage difference between the two pins
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For example, we measured 0.7V on one pin and 0.8V on the other pin
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Only when there is a voltage difference can it be normal
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The method of measuring voltage cannot guarantee 100% accuracy
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The fourth method is the replacement
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If it is inconvenient for us to measure, or there is no oscilloscope,
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we can directly replace the crystal oscillator
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Four measurement methods,
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the oscilloscope measurement method is the most accurate
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When it is judged that the crystal oscillator is damaged, we need to replace it
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Crystal Oscillator Replacement Method
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We need to find a crystal oscillator of the same size and parameters to replace
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For example, a crystal oscillator with a frequency of 24MHz,
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we must use a 24MHz crystal oscillator to replace
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When replacing, you also need to consider the size of the crystal oscillator
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Because the welding installation space of the mobile phone is relatively small,
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if the crystal oscillator is large,
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it may not be able to be installed on the mainboard
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When replacing, it is best to replace the resonant capacitor connected to the crystal oscillator pin together
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The capacitor connected to the crystal oscillator pin is a frequency matching capacitor
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If we do not replace the capacitor together, it may cause frequency deviation,
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and the fault is still not resolved
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Ok, that's all for this video
