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Recognition and Measurement of Electronic Components

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This video mainly explains the method of judging whether the capacitor is good or bad

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and the principle of capacitor replacement

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Resonant capacitor

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The resonant capacitor is the capacitor connected to the crystal pin

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For example, both C3051 and C3052 are resonant capacitors

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The main function is to assist the crystal oscillator to make the crystal oscillator generate the set frequency

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The resonant capacitor cannot be removed,

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and the frequency of the crystal oscillator will be abnormal after removal

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Capacitor quality judgment method

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The first step is to check the appearance of the capacitor

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The surface of a normal capacitor is relatively smooth,

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and the overall color is the same

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If we observe and find that the capacitor has cracks or missing corners,

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it means that the capacitor has been damaged

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During maintenance, some will encounter water entering the mainboard,

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and the capacitor will be corroded

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The two ends of the normal capacitor pad are relatively bright silver white

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Corroded capacitor will appear black or corroded

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Like this kind of capacitor, the value is normal when we measure it,

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but this kind of capacitor will cause a leakage fault after it is energized

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So corroded capacitors also represent damage

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In the second step, if there is no problem with the appearance inspection,

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we use a multimeter to measure the capacitance of the capacitor

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When measuring, adjust the multimeter to the F (Farad) position,

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and measure the two ends of the capacitor with the test markers

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When the measured value is consistent with the value marked in the drawing,

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it means that the capacitor is normal

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If the capacitance value shrinks, it means that the capacitor is damaged

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The third step, in actual maintenance,

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we rarely use a multimeter to measure the capacitance of the capacitor

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Generally, we will use the multimeter diode range to measure its diode value

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When measuring the diode value at both ends of the capacitor,

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the value shows OL, which means that the capacitor is normal

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If there is a value, it means that the capacitor will leak

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If it shows 000, it means that the capacitor is short circuited

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Precautions for the judgment

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It will be inaccurate when measuring capacitor on a mainboard

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because there are components connected to both ends of the capacitor

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To make an accurate judgment, you need to remove the capacitor and measure it

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Capacitor Substitution Principle

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The standard substitution principle is the same parameters, same size substitution

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In actual maintenance, some capacitors can be replaced after damage

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For example, if multiple filter capacitors are connected to the same line,

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if one or two are damaged, it is not necessary to install them after removal

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After the coupling capacitor is damaged, it cannot be removed,

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but can only be replaced with the same size and parameters

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Because the coupling capacitor is connected in series in the line,

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if it is removed, the line will be disconnected and the signal cannot be transmitted

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When the resonant capacitor is damaged,

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it is best to replace it with the crystal oscillator

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Because the resonant capacitor and the crystal oscillator are matched,

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if other capacitors are installed,

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it may cause the frequency of the crystal oscillator to deviate

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Ok, that's all for this video