1

00:00:01,200 --> 00:00:06,766

Hello everyone, in this lesson we will learn the measurement and judgment of triode

2

00:00:08,400 --> 00:00:11,733

Why do we need to measure the triode?

3

00:00:12,066 --> 00:00:14,900

Because the triode is divided into two types

4

00:00:15,066 --> 00:00:20,533

One is a PNP transistor, the other is an NPN transistor

5

00:00:21,200 --> 00:00:26,133

These two triodes are indistinguishable in appearance

6

00:00:26,600 --> 00:00:34,066

So we need to measure the triode to help us judge the type of triode

7

00:00:35,400 --> 00:00:40,900

When measuring the triode, you need to use the diode file of the multimeter

8

00:00:41,266 --> 00:00:47,733

The red marker of the multimeter is positively charged, and the black marker is negatively charged

9

00:00:49,133 --> 00:00:54,400

Let's first erase the area where the C pole is connected

10

00:00:54,866 --> 00:00:59,600

At this time, BE is equivalent to a diode

11

00:00:59,933 --> 00:01:04,600

Its measurement method is the same as that of a diode

12

00:01:04,666 --> 00:01:07,000

That is, the red marker is connected to the positive pole,

13

00:01:07,166 --> 00:01:09,566

and the black marker pen is connected to the negative pole.

14

00:01:09,900 --> 00:01:14,366

As shown in the figure, it is possible to measure the value of

15

00:01:14,533 --> 00:01:19,533

If the two markers are reversed, the value cannot be measured

16

00:01:20,466 --> 00:01:25,766

Let's erase the E pole again, and connect the C pole again

17

00:01:26,466 --> 00:01:30,833

We can see that there is still a diode between CB

18

00:01:31,633 --> 00:01:36,666

Their measurement method is still the same as that of the diode

19

00:01:37,733 --> 00:01:40,633

That is, the red marker is connected to the positive pole,

20

00:01:40,833 --> 00:01:42,466

and the black marker is connected to the negative pole.

21

00:01:42,766 --> 00:01:46,100

Connect the red marker to P, and the black marker to N

22

00:01:47,166 --> 00:01:50,133

At this time we got the measurement method of the triode

23

00:01:50,400 --> 00:01:53,933

For the NPN type triode, the red marker is connected to the B pole,

24

00:01:54,566 --> 00:01:57,700

and the black marker is connected to the other two poles.

25

00:01:58,366 --> 00:02:00,966

At this time, two values can be measured

26

00:02:04,333 --> 00:02:06,966

The other connection methods can not measure the value

27

00:02:07,433 --> 00:02:10,866

For the PNP transistor, the black marker is connected to the B pole,

28

00:02:11,100 --> 00:02:13,566

and the red marker is connected to the other two poles.

29

00:02:14,400 --> 00:02:16,733

The value can be measured

30

00:02:19,466 --> 00:02:22,133

The other connection methods can not measure the value

31

00:02:22,600 --> 00:02:27,633

Of course, the measurement method here refers to the off-line measurement method,

32

00:02:27,933 --> 00:02:31,100

that is, to measure after the triode is removed.

33

00:02:31,666 --> 00:02:37,000

If online measurement, other connection methods can also measure the value

34

00:02:38,233 --> 00:02:43,633

It's just that the value it measures is generally relatively large, generally greater than 700

35

00:02:45,366 --> 00:02:49,200

It is recommended that novices should remove the triode to measure

36

00:02:50,700 --> 00:02:57,200

After knowing how to measure the triode, let's take a look at the quality judgment of the triode

37

00:02:58,333 --> 00:03:01,500

There are two ways to judge whether the triode is good or bad

38

00:03:02,100 --> 00:03:05,566

The first is that if the measured logic does not match the logic of the triode,

39

00:03:05,766 --> 00:03:07,400

it means that the triode is damaged.

40

00:03:10,800 --> 00:03:13,900

For example, an NPN transistor

41

00:03:14,300 --> 00:03:17,500

Put the red marker on pole E and the black marker on pole B.

42

00:03:17,966 --> 00:03:20,633

It should be impossible to measure the value

43

00:03:20,866 --> 00:03:25,966

If the value is measured, it does not match the above measurement method

44

00:03:26,300 --> 00:03:28,966

It means the triode is damaged.

45

00:03:31,700 --> 00:03:37,733

The second measurement method is to look at the conduction logic of the triode after power-on

46

00:03:39,333 --> 00:03:43,733

If the transistor has reached the conduction condition, but does not conduct

47

00:03:44,000 --> 00:03:47,166

It means that the triode has been damaged.

48

00:03:49,233 --> 00:03:52,866

The commonly used judgment method in maintenance is the second

49

00:03:53,466 --> 00:03:57,900

That is, after power-on, observe whether the conduction logic is consistent with the logic of the triode