How to check the diode multimeter

To date, we can not imagine being without electronics, it surrounds us almost all the time. But, unfortunately, the electronics does not work forever, and a fairly common cause of failure is the failure of the diode. In this article I will tell you what is basically a diode and how it can be checked using an electronic multimeter.

What is a diode and how it works

Diode - an element board, representing a semiconductor with P-N junction and thereby has unidirectional conductivity.

Structurally simple diode has two outputs: a cathode (negative) and an anode (positive).

Note. This article discusses the simplest version of a diode, having only one P-N transition. In principle there may be more, for example, dynistor three.

The diode works as follows: when it is included in the chain of "directly", ie the "+" appropriate positive charge, and a "-" negative. In this case P-N discloses transition and conductor current flows, if on the "+" apply a negative value, and on negative - positive, then in this case the passage is closed and the current through the conductor passes.

On this simple principle and an algorithm for checking diode performance. Knowing this, you can begin to direct verification.

Check the serviceability of the diode

To do need diodes and diode test Multimeter successful integrity to us.

In the vast majority of multimeters have a diode test function and visually it looks like this:

To do this, simply translate the position of the regulator in this area, take the ends of the red and leans to the anode (usually manufacturers label his white stripe or simply write "-"), and black to cathode. In this case, you will see a certain value:

Moreover, this value is not resistance and threshold voltage.

Important. When the checks do not touch your fingers to the cathode and anode, as in this case, you do not get quite the correct readings.

Now change the ends of the meter check the locations and the diode in the reverse direction.

With this setup the meter on the dial you'll see a "1" in the most significant digit. It refers to the fact that in this area P-N junction is closed, no current flows.

From these measurements, we can conclude - LED is fully functional.

Types of diodes malfunction

There are only two kinds of diode failure, they are:

1. Breakdown. In this case, the diode becomes most common conductor through which current can move freely in any direction. When such a failure multimeter emits a thin squeak, and the display you will see a value close or equal to zero.

2. breakage. A diode in this case in principle no current passes into any direction and in fact becomes an insulator. In this display device, in both cases indicates "1". This damage can be diagnosed and wrongly, to avoid short-circuit at each test them for yourself to verify the integrity of all.

As you can see, diagnose faults data quite easily.

Is it possible to check diode, not vypaivaya it from schemes

This question is quite logical and understandable answer is that it is not: Fully desoldering diode from the circuit to check it not necessarily the only one of the "legs" vypayat enough, this will be sufficient for its full check.

If you do not make desoldering one "leg", then checking you get bad data, as in this case, the current will still flow scheme.

As for the testimony of a multimeter to understand on what technology and what material is made diode

Check a different diodes, you may notice that the meter readings are different and sometimes quite substantially. This is due to the fact that the diodes are made of different materials and different technologies. And for this indication can be determined from which they are made:

That's the uncomplicated way there is a check on the performance diodes and serviceability. Thanks for attention.