How to check the quality of the LCD screen with a multimeter

a-: Move to a certain location where the DC current is measured.

cx: Use it to measure the capacitance of a capacitor. For example, if a capacitor indicates 1000 microfarads, it is good to measure roughly close to about 1000 microfarthers, and if the difference is too large, it is bad.

v: Move there to measure the AC voltage. The 220V voltage used in your home is measured with this gear.

Move to this position to measure the resistance value, for example, if you want to measure the resistance of a light bulb filament in ohms or the resistance of a certain resistance on a circuit board, the quality of the diode is measured in this way.

When measuring, according to the different values measured, different ranges should be selected, for example, the AC 220V multimeter should be moved to the position of V 250 for measurement. Another example; If a resistance is 1,000 ohms, you should move the gear to x100 for measurement, which will help the measurement to be accurate and not burn out the multimeter.

1) To check whether the capacitor on the motherboard is good or bad, prepare an electric soldering iron, solder the end of the capacitor, that is, one end is out of the circuit board, you can use the x1k ohm file of the multimeter to measure the feet of the capacitor, at the moment when the multimeter pen turns on the capacitor, the pointer of the dial immediately rushes to the highest gear, and then it will slowly drop to 0, indicating that the capacitor is good. Without the charge-discharge characteristics described above, the capacitor may fail.

2) Measuring resistance: also solder one end, the multimeter is moved to a suitable ohm file to measure, for example, your ohm file is moved to the x100 level, and the pointer of the multimeter is at the position of 5, then the resistance is 5x100 = 500 euros.

3) Measuring diode: also solder open one end, use the x1k ohm file to exchange two meter pens to measure the two feet of the diode twice, if it is a good diode, once the meter pointer to the full gear, once the finger does not move at the 0 position. Otherwise the diode is broken.

4) Test the fuse: the multimeter can be moved to any gear in the ohm file, preferably in the x1k file, the good finger is in the full gear, and the bad pointer does not move.

5) Measuring transistor; To weld the two pins, the multimeter is also moved to the x10 position of the ohm file, and the resistance value of the two pins is about 300 ohms. There are many types of transistors, and different transistors have different measurement methods, so I won't talk about it here.

I believe it will help you, and I hope you will become a master of using multimeters.

Note: The above is described with an analog multimeter, and the digital multimeter is much the same. Content excerpted from:

Are you satisfied with the above?

Whether the LCD screen is good or bad can not be checked with a multimeter,There are vertical bars on the boot screen,There should be no problem with the LCD screen,Call to repair the TV to see it clearly。

The multimeter is not good for measuring the LCD screen.

There are several ways to do this:

1. Visual inspection: You can touch whether the temperature rise of the battery, resistor, transistor and integrated block is too high. If a newly installed battery generates heat, the circuit may be short-circuited. In addition, the circuit should also be observed for disconnection, desoldering, mechanical damage, etc.

2. Waveform analysis: use an electronic oscilloscope to observe the voltage waveform, amplitude, period (frequency), etc. of each key point of the circuit. For example, if the oscillator is not vibrating, if the oscillator has no output, the internal inverter is damaged, or the external components may be open.

3. Measuring element parameters: For the components within the fault range, the parameter values should be analyzed for advanced measurement or offline measurement. For resistor** measurements, the effects of the components connected in parallel should be considered.

4. Use a multimeter to measure the horn: use R 1 gear, either watch pen touches one end, and the other watch pen touches the other end, and it will make a crisp sound of "click" under normal times. If it doesn't sound, the coil is broken, and if the sound is small and high, it means that there is a problem of rubbing the coil and it can't be used.

5. Test the measurement with 1 ohm level, and the sound in the horn is good, and the sound without sound or no resistance value is bad. The horn resistance is small, generally a few ohms, which can be ignored. If there is a sound in the point measurement horn, but it is not a one-time sound, it is not qualified.

1.The end knob (or jack) is selected correctly.

The red pen cable should be connected to the red end button (medium width or marked "+" jack), the black pen should be connected to the black end button (or connected to the "—" jack), some multimeters are equipped with AC and DC 2500 volt measurement end buttons, the black test rod is still connected to the black end button (or "—" jack), and the red test rod is connected to the 2500 volt end button (or in the jack).

2.The position of the transfer switch should be selected correctly.

Depending on the measurement object, the transfer switch is turned to the desired position. If the current of the excavation current is measured, the transfer switch should be turned to the corresponding current level, and the measured voltage should be transferred to the corresponding voltage level. Some multi-purpose surface plates have two transfer switches, one for the measurement type and the other for the measurement range.

When using it, you should first select the measurement type, and then select the measurement range.

3.The range should be selected appropriately.

Depending on the approximate range to be measured, the transfer switch is turned to the appropriate range of the type. When measuring voltage or current, it is best to have the pointer within one-half to two-thirds of the range for accurate readings.

4.Take the reading correctly.

There are a number of scales on the dial of a multimeter, which are suitable for different objects to be measured. Therefore, when judging the stool measurement, while reading on the corresponding scale scale, it should also pay attention to the cooperation between the scale reading and the range file to avoid errors.

5.Proper use of ohms.

Choose the appropriate magnification range: When measuring resistance, the magnification file should be selected so that the pointer stays in the thinner part of the scale mark, the closer the pointer is to the middle of the scale, the more accurate the reading, the more left, the more crowded the scale mark, the worse the accuracy of the reading.

Zeroing: Before measuring the resistance, the two test rods should be touched together, and the "zeroing knob" should be turned at the same time so that the pointer is just pointing at the zero position of the ohmic scale, this step is called ohmic zeroing. This step is repeated every time the ohm is changed before measuring the resistance to ensure the accuracy of the measurement.

If the pointer cannot be adjusted to the zero position, it means that the battery voltage is insufficient and needs to be replaced.

The multimeter is powered by a dry battery when measuring the resistance, and the measured resistance must not be charged to avoid damaging the meter head. When using ohmic gaps, do not short-circuit the two test rods to avoid wasting battery.

6.Pay attention to operational safety.

When using the multimeter, it is important to note that the metal part of the test rod should not be touched by hand to ensure safety and measurement accuracy.

When measuring higher voltages or larger currents, the transfer switch should not be turned live, otherwise the switch may burn out.

After the multimeter is used up, it is best to turn the transfer switch to the AC voltage maximum range, which is the safest for the multimeter, in case the multimeter is inadvertently damaged during the next measurement.

When the test rod touches the tested line, a comprehensive inspection should be done again to see if the position of each part is wrong.

Electrician maintenance skills sharing, electrical automation skills and knowledge, power drive control system principle wiring explanation!

A multimeter is actually called a three-purpose meter. It is mainly to measure the three basic physical quantities of resistance, voltage and current. The functions of other test diodes and transistors are also calculated by the variation of these three items.

A DMM uses the CPU to read a component to be measured.

There are a few reasons why the display numbers you said would jump around.

1: Your measurement is unstable, so it will cause random jumping, which is the result of correct reading. It's not to blame that there is a problem with the multimeter, it's that the physical quantity to be measured is indeed changing;

2: Your multimeter has high accuracy. For example, the accuracy of your multimeter is accurate, so for the general voltage, current and other voltage stabilization, filtering does not reach the ultimate circuit, there will definitely be a beating envy socks. This situation is the same as the first;

3: The battery of the multimeter is low. In this case. It's not just that it beats. It can also be felt that the display is not so clear. In fact, the measured values are no longer accurate at this time.

Therefore, the multimeter should generally be turned off after use, of course, the current multimeter will automatically turn off. It takes a little more time, though. And if you don't use it for a long time.

It is recommended to remove the battery. In order to avoid the battery not being used for a long time, it will cause battery leakage. If you need a measurement with high accuracy, you should choose or negotiate a multimeter with high accuracy.

It is necessary to calibrate the accuracy of the multimeter regularly.

This one is simple. I've used two numeric tables a lot. I don't know what you said, why your multimeter is not normal. I can only say it in general terms.

First of all, the digital meter is not easy to break, even if the measurement range is wrong, it generally cannot be broken. At most, you can pay for insurance, and the insurance can be seen when you open the back cover.

When the voltage level of the digital meter is not measured, the number will change continuously in a small range, which is normal.

If the battery is dead, a battery symbol will be displayed on the screen. You just have to listen to it.

It is often the case that the contact of the watch pen is poor, and you can go to the hardware store to buy a pair for 5 yuan.

The digital meter resistance measurement type is very accurate, find a numerical value to measure it, but the value of the resistance is allowed to have a 5% error. Measure the voltage at home, generally 220-240 is normal.

One battery, two meter pens, each end to the voltage gear to see if there is a display.

It is impossible to measure the quality of LED with an ordinary pointer multimeter, because the working voltage of LED is around the right, and the internal voltage of an ordinary pointer multimeter is only, so when measuring LED with the resistance of an ordinary multimeter, its forward and reverse resistance values are infinite.

You can use a pointer multimeter with a high-voltage battery (with R 10K gear) to measure the LED, such as the MF47 type multimeter, use the R 10K file to measure, the forward conduction of the LED, the reverse resistance is infinite, which means that the LED is good.

You can also use the diode file of the digital multimeter to measure the quality of the LED, the red table pen is connected to the positive pole of the LED, and the black table pen is connected to the negative pole of the LED, at this time the digital multimeter is displayed at about 1700, and the reverse measurement will be infinite, showing "1--- which can basically prove that the LED is good.

If the LED is a high-brightness LED, it will emit a faint light when measuring with a digital multimeter diode, and it will also have a faint light when measuring in the R 10K position of an analog multimeter.

The multimeter amplifier is in the diode setting, where there is a voltage of about 2V between the two pencils, which can light up most LEDs (single). The red pen is +, and the black pen is -

The multimeter has a gear that detects short circuits and adjusts to that gear. Use the multi-purpose positive meter pen to contact the positive electrode of the LED, and the negative meter pen to contact the negative electrode of the LED. The LED is on, which means that the LED is normal.

The method of measuring the quality of LED with a multimeter is as follows:

Tools: multimeter, LED light.

Flip the knob on the multimeter to the diode (beep) setting and insert the red and black pen into the correct position of the multimeter.

There are two kinds of observation tubes: four-legged and two-legged, and if it is four-legged, the middle two feet are selected. Touch the red and black watch pen to the two pins to be detected, if there is a beep and the red LED light of the multimeter is on, the lamp is good, otherwise the lamp is broken.

If it is a two-legged lamp, the lamp head will be disassembled, and you will find that there are four wires, and the subsequent measurement method is the same as that of the four-legged lamp.

The first step in learning the multimeter is to master the use of buzzer and diode gear, and most of the maintenance measurements in life can be used.