How to test a Schottky diode with a multimeter?

Как проверить диод Шоттки

Due to the speedwork, Schottky diodes are often used in the pulse stabilizers, as well as in the PC power supplies rectifiers. The check for the Schottky diode operability does not differ much from the verification of the common diode, it is carried out in a same way. The only moment that is needed to take into account, that the Schottky diodes, which are used in a high quality powerunits, are often met doubled in a single case and have a joint cathode. So, today we will tell how to check the Schottky diode with a multimeter and detect all the defects?

How to check a Schottky diode with a multimeter?

For clarity, we will conduct a small test of the Schottky diode SBL3045PT. This diode is from the PC power supply, estimated by the manufacturer up to 45 V, 30 A. (i.e., 15 A for each diode).

It is necessary to take one moment into consideration, when using dual-type diodes in rectifiers – that the manufacturer often indicates the current for the assembly as a whole, and not for each diode in the assembly.

How to check a Schottky diode

A schematic test of a dual Schottky diode with a joint cathode is shown below. We can see that each of the two diodes must be checked in turn.

How to test a Schottky diode with a multimeter

Vividly shown how to test the Schottky diode with a multimeter?

How to test a Schottky diode

Important! When checking the diode, it is possible and important to find defects not only breakage or breakdown. It is necessary to try to take into account such an unpleasant defect as a small “leak”.

If we performed a check with a multimeter’s check mode “diode” and it  showed quite a working element, but the leak is being suspected, then it is necessary to try measure the reverse resistance of the diode, having previously switched on the multimeter’s mode ohmmeter. On a range of “20 kOhm” the multimeter should display the reverse resistance of the diode as infinitely large. But if the tester shows a little resistance, for example, about 2-3 kOhm, then it is necessary to apply to such a diode with a big suspicion and is better to replace it immediately with a new one.

One of the biggest drawbacks of Schottky diodes is that they are out of order at once if exceeded the permissible voltage. Considering all the moments of independent repair of static power supply units, in case of defective diodes detection and after replacing them, all power transistors need to be checked immediately for operability.

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