How to measure the quality of electrolytic capacitance with a pointer meter?

Check the quality of the capacitor: use x100 gear. Connect the multimeter pen to the two leads of the capacitor respectively, and replace the two leads of the capacitor with the two leads of the capacitor after connecting the multimeter pen to the two leads of the capacitor after the swapping, and the first step can be repeated.

Capacitor damage phenomena are mainly short circuits, open circuits and leakage currents. Among these items, the short circuit is easier to judge, and the resistance at both ends of the capacitor is close to zero, which can be regarded as a short circuit. The open circuit is also easier to judge, that is, there is no charging and discharging process, but for small capacity capacitors, because the charging and discharging are not obvious, it is best to test the capacitor file to confirm.

If it is an electrolytic capacitor with a relatively large capacity, when measuring, if it is a digital multimeter, then the red meter pen is connected to the positive pole of the capacitor, if it is a pointer multimeter, it is the positive pole of the black meter pen connected to the capacitor, when measuring, because the capacity is relatively large, there is a charging process, and the resistance value will have a gradual increase process. In this process, until the resistance value is stable. The electrolytic capacitor with low withstand voltage and large capacity has a resistance value after stabilization, which can be regarded as the leakage value.

Such capacitors allow some leakage, as for how much this value is good, different models of multimeters, different capacitance values, there are differences. It is not possible to measure the capacitance value of a multimeter without a capacitor file, or if the capacitor range is insufficient. You can use a good capacitor, when measuring, look at the pointer, or the minimum value of the value, to compare and confirm the quality of the capacitance.

When measuring, pay attention to the capacitance to be fully discharged before measurement.

How do pointer multimeters and digital multimeters measure the quality of capacitance? Teach you the easiest way, simple and practical.

1. Visual inspection of appearance

When we get a faulty board, we can use the simplest visual inspection method. If a capacitor is observed to be leaking, bulging, or burning, it is a sign that the capacitor is damaged. This method can only find severely damaged capacitors, but it cannot tell whether a capacitor with a good appearance is normal.

2. Multimeter capacitance file measurement

Turn on the DMM and dial the multimeter to the capacitor setting. Then, according to the capacitance of the capacitor to be measured, the corresponding range is selected. Digital multimeters generally have five gears such as 20N and 200N.

Once the range is selected, insert the two pins of the capacitor directly into the CX jack to start the measurement. If there is a polar capacitance, pay attention to the positive and negative poles. We can then tell if the capacitor is damaged based on the capacitance displayed by the digital multimeter.

If the measured capacity is lower than the nominal capacity, the capacitor has been damaged.

3. Multimeter resistance measurement

Under normal circumstances, the resistance of the multimeter is less than 10k, and the output voltage of the multimeter is greater than 10k, and the output voltage is 9v. If the capacitance of the capacitor to be measured is relatively large, it is measured with a small range of resistance, and if the capacitance of the capacitor to be measured is relatively small, it is measured with a large range.

1. Direct detection with capacitor file.

2000p, suitable for measuring capacitance less than 2000pf; 20N, suitable for measuring capacitance between 2000PF and 20NF; 200N, suitable for measuring capacitance between 20NF and 200NF; 2nd gear, suitable for measuring capacitance between 200 nF and 2 F; 20 steps, suitable for measuring capacitance between 2 F and 20 F.

Second, use the resistance file to detect.

1. Measurement operation method.

As shown in the figure below, when the DMM is set to the appropriate resistance setting, the red and black pencils touch the poles of the capacitor CX under test, respectively, and the display value will gradually increase from "000" until the overflow symbol "1" is displayed.

If "000" is displayed all the time, it means that the capacitor is short-circuited; If spill is always displayed, there may be an open circuit between the internal poles of the capacitor, or the selected resistance range may not be suitable. When checking the electrolytic capacitor, it should be noted that the red pen (positive) is connected to the positive pole of the capacitor, and the black pen is connected to the negative pole of the capacitor.

2. Measuring principle.

Figure 5-11(b) shows the measurement principle of a capacitor measured with a resistance position. During the measurement, the positive power supply is charged to the capacitor CX under test through the standard resistor R0, and at the moment of charging, "000" is displayed because of VC 0.

As the VC increases, the display value increases. When VC 2VR, the meter starts displaying the overflow symbol "1". The charging time t is the time required for the display value to change from "000" to overflow, and this time interval can be measured with a quartz meter.

There are three ways to measure the magnitude value of capacitance:

1. Direct detection with capacitor file.

When measuring, insert the two pins of the discharged capacitor directly into the CX jack on the meter board, and the display data read after selecting the range is the capacitance magnitude value.

2. Detect with resistance gear.

Assuming that the measurement rate of the digital multimeter is n times a second, n independent and sequentially increasing readings can be seen every second while observing the charging of the capacitor.

3. Detect the use of electric limbs to celebrate the pressure gear.

Detecting a capacitor with a digital multimeter DC voltage level is actually an indirect measurement method that measures a small capacitance capacitor of 220 pf 1 F and accurately measures the leakage current of the capacitor.

<>1. Use the pointer multimeter electrical detection: first of all, the pointer multimeter should be adjusted to the resistance level, the gear is r*1k, and then connect the black meter pen on the positive pole of the capacitor, connect the red meter pen on the negative pole, and finally look at the change of the multimeter pointer, if the pointer fluctuates, and returns to zero after discharge, the capacitance is normal, otherwise it means that the capacitance is damaged.

2. Use the digital multimeter diode detection: adjust the multimeter to the diode file, and then connect the meter pen on both sides of the capacitor.

4. Direct detection with capacitor: dial the digital multimeter to the test sock filial piety gear, and then connect the black pen meter to the positive pole of the capacitance, and the red pen to the negative pole, when the capacitance appears infinite, it means that the capacitor is open and leaky, and needs to be repaired. When the capacitance is zero, it means that it has been broken down, and the other numbers are normal.

5. Detection by resonance method: This detection method is very simple, mainly to detect the LC resonant circuit, if the number and waveform are normal, the capacitance is normal, otherwise it means that it is damaged and needs to be repaired. The mountain is good.

<>1. Use a pointer multimeter for detection. Adjust the multimeter first, select the corresponding position, connect the black one on one side, and connect the red one on the other, and then you can test it after the ruler. If the needle inside moves, but finally returns to the zero position, then Wu Lu means that it is normal and can continue to be used.

2. Detect with a digital multimeter diode. There is also a digital watch, which can be adjusted to the second gear, and then connected to the pen, and it can be detected. If it makes a dripping sound, it means that it is broken, and it needs to be replaced with a new one.

3. Direct detection with capacitors. The first thing to choose is to choose the gear, and then to connect the electric pen, if it is infinite, it means that it is leaking and needs to be repaired before you can continue to use it.

Here's how to measure the quality of capacitance:

1. Multimeter detection method:

For the above fixed capacitors. The capacitor can be directly tested with the R 1k stop of the multimeter for the charging process and whether there is an internal short circuit or leakage, and the capacitance of the capacitor can be estimated based on the amplitude of the pointer swinging to the right.

When testing the operation, first touch the two pins of the capacitor with two meter pens, and then change the meter pen to touch it again, if the capacitance is good, the multimeter pointer will swing to the right, and then quickly return to the infinity position to the left. The greater the capacitance, the greater the swing of the pointer.

If the multimeter needle does not swing to the right after repeatedly changing the meter pen and touching the two pins of the capacitor, the capacitance of the capacitor has been reduced or has disappeared. During the measurement, if the pointer swings to the right and cannot return to the infinity position to the left, it means that the capacitor has leaked or has broken down.

2. Simple fuse detection method:

The fuse (the rated current of the fuse in is determined by the following formula: in=, where c is the capacitance of the capacitor) and the capacitor to be detected are connected in series on the AC power supply of 220V, if the fuse of the fuse bursts, it means that the capacitor has been short-circuited inside.

If the fuse of the fuse does not burst, after a few seconds of charging, cut off the power supply, and use a screwdriver with an insulating handle to short-circuit the two poles of the capacitor to discharge, and if there is a spark, the capacitor is good. Conversely, it means that the capacitance of the capacitor has become smaller or has been opened. Judging the quality of capacitors with this method should be repeated several times to get the correct conclusion.

3. Incandescent bulb and capacitor series detection method:

Connect the incandescent bulb and the capacitor in series to the 220V AC power supply, if the brightness of the incandescent bulb is darker than if it is directly connected to the 220V AC power supply, the capacitor is good.

If the incandescent bulb does not light up, it means that the inside of the capacitor to be tested has been disconnected; If the brightness of an incandescent bulb is the same as the brightness of the bulb that is connected directly to the 220V AC power supply, the inside of the capacitor has been shorted.