Checking various transistors: rules and recommendations

How to ring a transistor: setting the multimeter

Each multimeter, in which there is a special mode, depicted on the device with a diode icon. Conclusions of the multimeter need to be connected in the same way as the connection in the resistance mode: the black wire to the COM port, and the red one to the output of the resistance, frequency and voltage measurement. An outdated analog device may not have this mode, so you need to install a resistance measurement mode on the device and set the highest measurement limit of the switch.

How to test bipolar transistor?

The bipolar transistor is an alternation of semiconductors. There are pnp and npn types. The check is carried out in the same way as checking the diodes.

It is possible to check the serviceability by following these recommendations:

1. To correctly connect the terminals of the multimeter to the terminals of the transistor, it is necessary to determine the location of the base, collector and emitter. To determine the base, we connect the black probe to the base first electrode, and the second one( red) first to the second electrode, then to the third one. Swap the probes in place until the multimeter shows a certain voltage drop. Then it can be noted that this pair is a "base-collector" or "base-emitter".The location of the emitter and collector can be determined using a digital multimeter. Most often, the resistance and voltage drop is slightly larger for the emitter junction.
2. It is necessary to place the measuring device in the usual mode of resistance measurement. The approximate measurement limit to be set is -2000.
3. The multimeter is connected to each pair of contacts in two directions. The measurements are carried out and the results are compared.
4. The bipolar transistor can be considered operable if, during the measurement of one polarity on a multimeter, the existence of a finite resistance is shown, and at the reverse - shows unity. It is not necessary to solder the part from the board.

How to check the igbt transistor?

It is not recommended to check the transistors with an isolated gate yourself, as the manufacturers of such parts, as a rule, test them. Self-check should be done very carefully, so as not to damage the radio components.

When testing, it is necessary to adhere to such rules:

1. The multimeter should work in the diode test mode.
2. Remove the conductive material and close the base to the emitter only when the part is outside the circuit.
3. It is necessary to connect the IP to the gate and collector, then to the gate and emitter and measure the resistance. If the device is working, the measured resistance will be equal to infinity.

How to test a FET?

Field-effect transistors are more sensitive than bipolar ones, because they are controlled by a field that is applied to the gate with a voltage. Checking the field effect transistor with a multimeter differs significantly from the previous one. A necessary condition that determines the serviceability of the field-effect transistor is that an infinite resistance is displayed between the three terminals of the instrument on the multimeter screen.

To understand how to ring a FET, you need to pay attention to some of the nuances. The test has two subtleties:

1. In high-power transistors in the circuit between the drain and source there is a diode.
2. Touching the gate with a positive or negative terminal, the gate opens and the channel resistance decreases.

During the field-effect transistor test, the device feet must be shorted.