How to check the multimeter Transistor: testing of different types of devices

Before you start repairing the electronic device or assembly of circuits should make sure in good condition all the elements that will be installed. If new parts must be sure they work. The transistor is one of the main constituent elements of many electronic circuits, so it should ring out in the first place. How to check the multimeter transistor describe in detail in this article.

What is a transistor

The main component is any wiring transistor which under the influence of the external signal controls the current in an electrical circuit. Transistors are divided into two types: bipolar and field.

The bipolar transistor has three terminals: base, emitter and collector. On the base current is supplied to a small size, which causes a change in the emitter-collector resistance zone, which leads to a change in the flowing current. Current flows in one direction, which is determined by the transition type and corresponds polarity.

A transistor of this type has two p-n junctions. When the electron conductivity (n) dominates at a device region and in the middle - the hole (p), the transistor is called n-p-n (reciprocal conductivity). If on the contrary, then the device is called transistor-type p-n-p (forward conduction).

Field effect transistors are of the bipolar characteristic differences. They are equipped with two working conclusions - the source and drain, and a control (gate). In this case, the gate voltage is affected, not the current, which is typical for a bipolar type. Electrical current passes between the source and the drain with a certain intensity, which depends on the signal. This signal is generated between the gate and source or gate and drain. A transistor of this type may be a control p-n transition, or insulated gate. In the first case the working conclusions are connected to the semiconductor wafer, which may be p- or n-type.

The main feature of the field effect transistors is that their management is provided not by the current, and voltage. Minimal use of power allows it to apply to radio details with quiet and compact power sources. Such devices may have different polarity.

How to check the multimeter transistor

Many of today's testers are equipped with specialized connectors that are used to test electronic components performance, including transistors.

To determine the operating state of the semiconductor device, it is necessary to test each element. Bipolar transistor has two p-n transition in the form of diodes (semiconductors) which are oppositely connected to the base. Hence a semiconductor is formed a collector terminal and the base, and the other of the emitter and base.

Using transistor to build the circuit board need to clearly know the purpose of each output. Improper placement of the element can lead to burnout. If the tester can be used to learn the purpose of each output.

Important!This procedure is only possible for non-defective transistor.

For this purpose the device is translated into a resistance measuring mode to the maximum limit. Red probe should touch the left and to measure the contact resistance on the right and the intermediate tap. For example, the display values ​​of 1 and 817 ohms.

Then the red probe should be moved to the middle, and with the help of black resistance measured on the left and right terminals. Here, the result may be: infinity and 806 ohms. Red probe to translate to the right contact and take measurements of the remaining combinations. Here, in both cases, the display will show a value of 1 ohm.

Making the conclusion of all the measurements, the base is located on the right of withdrawal. Now, to determine the other findings need to install the black test lead to the base. At one output is shown the value of 817 ohms - this emitter junction and the other corresponds to 806 ohms, the collector junction.

Important!The resistance of the emitter junction will always be greater than the collector.

How to ring multimeter transistor

To make sure the device in good condition enough to learn the forward and reverse resistance of its semiconductors. For this tester is translated into a resistance measuring mode and is set at the limit 2000. Followed by ring out every couple of contacts in both directions. So runs the six dimensions:

• compound "base-collector" must conduct electrical current in one direction;
• compound "base-emitter" conducts electrical current in one direction;
• Connect "emitter-collector" does not conduct electrical current in either direction.

As prozvanivat multimeter transistors whose conductivity p-n-p (arrow emitter junction is directed towards the base)? To do this, touch the black probe to the base, and red alternately touch the emitter and collector junctions. If they are correct, then the tester will be displayed directly 500-1200 ohms resistance.

To check the reverse resistance of the red probe should touch base, and black alternately to the terminals of the emitter and collector. Now the device should show on both transitions high resistance value by displaying "1" screen. So, both transitions are correct, and the transistor is not damaged.

This technique allows to solve the problem: how to check transistor multimeter, not vypaivaya it from the board. This is possible because the device transitions are not shunted low value resistors. However, if in the course of measurements the tester will show a too small value of forward and reverse resistance emmiternogo and collector junctions, the transistor have to unsolder from the circuit.

Before check multimeter n-p-n transistor (arrow directed from the emitter junction of the base), the red probe tester to determine the resistance connected directly to the base. The efficiency of the device is verified using the same method as that of the transistor with conductivity p-n-p.

On transistor open faults indicates one of the transitions, where the detected value of the direct or high reverse resistance. If this value is 0, the transition is in the cliff, and the transistor is faulty.

This technique is suitable only for bipolar transistors. Therefore, before testing is necessary to ascertain whether it relates to a composite or field device. Next, check between the emitter and collector resistance. Circuits should not be here.

If for assembling an electrical circuit necessary to use a transistor having an approximate value of the current amplification factor, with a tester can determine a desired item. To do this, the tester is translated into hFE mode. Transistor being connected to the corresponding device for a specific type socket located on the instrument. The screen should display the meter value h21 parameter.

How to check the multimeter thyristor? He has three p-n junctions, unlike a bipolar transistor. There structures alternate with each other in the manner of a zebra. Its main difference from the transistor is that the mode after entering the control pulse remains unchanged. The thyristor will remain open until the current until it falls to a certain value, called a holding current. Using SCR allows you to collect more economical wiring.

The multimeter is set to measure the scale of resistance in the range of 2,000 ohms. To open the black lead of the thyristor is connected to the cathode and the red to the anode. It should be remembered that the thyristor can be opened positive and negative pulses. Therefore, in both cases, the resistance of the device is less than 1. The thyristor remains open if the control signal exceeds the threshold current confinement. If the current is less, then the key is closed.

How to check the multimeter transistor IGBT

Insulated-gate bipolar transistor (IGBT) is a three-electrode power semiconductor apparatus in which the principle of cascading two transistors connected in one structure: Field and bipolar. First, the control channel, and the second - channel power.

To check transistor multimeter must be set to the semiconductor test mode. Thereafter, using the probe to measure the resistance between the emitter and the gate of the forward and backward direction to detect circuit.

Now red device connected to the emitter wire, and a black shutter touch briefly. Gate charge will occur a negative voltage, allowing the transistor to remain closed.

Important!If the transistor is equipped with a built-in antiparallel diode which anode is connected to the emitter of the transistor and the cathode to the collector, it is necessary to ring accordingly.

Now you need to verify the functionality of the transistor. First it is necessary to charge a positive voltage input capacitance of the gate-emitter voltage. For this purpose, both short red probe should touch the shutter, and black to the emitter. Now you need to check the collector-emitter voltage by connecting the black lead to the emitter, and the red to the collector. The screen should display multimeter slight voltage drop in the 0.5-1.5 V. This value for a few seconds should remain stable. This indicates that the input capacitance of the transistor leakage there.

Useful advice!If the meter is not enough voltage to open the IGBT transistor, then the DC power supply can be used to charge its input capacitance at 9-15 V.

How to check the multimeter FET

FETs exhibit a high sensitivity to static electricity, so the pre-ground organization is required.

Before you begin to check the FET, you should determine its pinout. On imported devices are usually applied labels that define the output device. The letter S denotes a source device, the letter D corresponds to the drain, and the letter G - shutter. If pinout is missing, then it is necessary to use the appliance.

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Before you check the functioning of the transistor, it is worth considering that the modern radio-type MOSFET additional diode are disposed between the source and the drain, which is necessarily applied to circuit instrument. The polarity of the diode is completely dependent on the type of transistor.

Useful advice!Protect itself from the accumulation of static charges can be using antistatic grounding strap which is worn on the arm or hand touch to the battery.

The main problem is how to test multimeter FET not vypaivaya it from the board consists of the following:

1. Must be removed from the transistor static electricity.
2. Switch the measuring device in the semiconductor test mode.
3. Connect the red test lead to the "+" instrument jack and the black "-".
4. Touch the red wire of the source and drain of the transistor black. If the device is in operation the display displayed voltage measuring device 0.5-0.7 V.
5. Black plug to connect to the source of the transistor and the red to the drain. The screen should display infinity, indicating the working condition of the device.
6. Open transistor by connecting the red probe to the gate, and black - to the source.
7. Without changing the position of the black wire, connect the red probe to the drain. If the transistor is defective, then the tester will voltage in the range of 0-800 mV.
8. By changing the polarity of the wires, voltage reading should remain unchanged.
9. Run transistor close, connecting the black lead to the gate, and red - to the source of the transistor.

Talk about the good working condition of the transistor can be based on how it using a DC voltage from the tester has the ability to open and close. Due to the fact that the field effect transistor has a large input capacitance to discharge it will take some time. This characteristic is important when the transistor is initially opened by a voltage generated by the tester (see. P. 6), and for a small amount of time, measurements are carried out (see. Claim 7 and 8).

Checking multimeter operating state p-channel field-effect transistor is carried out in the same manner as the n-channel. Just start the measurement, by connecting the red probe to the negative terminal, and the black - to positive, ie.. change the polarity of the tester connection cables on the back.

Serviceability each transistor irrespective of the type of device can be checked by a simple multimeter. To do so clearly know the type of item and to define the marking of its conclusions. Further, in the diode mode continuity or resistance measurements found forward and reverse resistance of its transitions. Based on the results, to judge the proper state of the transistor.

How to check the multimeter Transistor: video instruction