场效应管(MOS管)如何判断好坏？

1、场效应管(MOS管)如何判断好坏？Detection of junction fetCheck the electrodes and the tubesTo use the black pen to pick up an electrode, use the red pen in turn to touch the other two electrodes, using the multimeter R x 100 or R * 1k. If one electrode is measured and the other two electrode resistance are very bi

2、g (infinite) or resistance are small (a few hundred ohms to one thousand ohms), can judge the black pens and pick up the grid G, the other two electrodes is both the source and drain D S.In a measure of high resistance for both blocks, the tube was measured as P channel junction fet. In a measuremen

3、t of low resistance of both blocks, the tube was measured as N channel junction fet. It is also possible to measure the positive and reverse resistance values between any two electrodes of a junction fet. If measured a positive and reverse resistance between two electrodes are equal, and thousands o

4、f ohms, are the two electrodes respectively, drain and source D S another electric grid G.The source and drain of the junction fet are symmetrical in structure and can be used interchangeably. If the positive and reverse resistance value of a transistor is zero or infinity, the tube has been punctur

5、ed or damaged.Check for amplificationMultimeter is R x 100 files, red pens and the field effect tube source S, black pens and pick up the drain D, leakage, the source is measured after the resistance value between the RSD, reoccupy hand knead letter grid G, multimeter swing to the left or the right

6、hand side (most of the field effect tube RSD will increase, the clock swing to the left; reduce the RSD minority field effect tube, the clock to the right). As long as the needle has a larger wiggle, it means that the tube has larger amplification capability.Double grid fet detectionThe detection of

7、 electrodesMost of the double gate field effect transistor pin position sequence is the same, that is, from the bottom of the field effect transistor () on the back of the tube body, counterclockwise direction of drain D, the source S grid, grid G1 and G2. Therefore, you can find two grids by using

8、the multimeter to measure the drain D and the source S.When testing, the multimeter can be placed in R x 100, and the positive and reverse resistance values of the two pins are measured with two pens. When measure the positive and reverse resistance between the two feet are a few ohms to thousands o

9、f ohm (the rest of the resistance between pins are infinity), the two electrodes is the drain and source D S, the other two electricity grid G1 and grid G2.Estimate amplificationMultimeter is R x 100, red pens and pick up the source S, black pens and drain D, in the measurement between the drain and

10、 source D S resistance RSD, fingers hold two grid, add the human body induction signal. If the resistance of RSD is large and small, it indicates that the tube has certain amplification. The greater the number of table Pointers to the right, the stronger the magnification.Judge whether it is good or

11、 badThe resistance value between the transistor source S and the drain D is measured by using the multimeter R x 10 or R x 100. Normal, positive, reverse resistance is a few dozen ohms to several thousand ohms. The resistance of the black marker, which is a black marker, is slightly larger than that

12、 of a black marker and a red marker. If the resistance value between D and S is zero or infinity, it indicates that the pipe has been damaged or damaged. Use the multimeter R x 10k to measure the resistances of the remaining pins (except for D and S). Normally, the grid G1 and G2, G1 and D, G1 and S

13、, G2 and D, G2 and S, should all be infinite. If the resistance is abnormal, the performance of the tube is poor or damaged.(3) the test of the VMOS high power field effect transistorCheck the electrodes and the tubesThe positive and reverse resistance value of the fet is measured by using the multi

14、meter R x 100. In one of the measurements, the two pins had resistors of hundreds of ohms,At this point, the two pens are connected to the source S and the drain D, while the other is the grid G.The positive and reverse resistance values of two pins (drain D and source S) are measured using the mult

15、imeter R x 10k. Normal, positive resistance value is about 2 k , the reverse resistance value is larger than 500 k.When electric resistance reverse, pin, red pens and receive black pens and out of the joint pin, first with the grid G touch once, and then to pick up the original pin, observe the chan

16、ge of the multimeter reading. If the multimeter reading is converted from the previous large block to zero, then the red marker is the source S, and the black marker is connected to the drain D. The power of the grid G with a black marker is shown to be an N channel field effect tube. If the multime

17、ter reading is still the larger value, the black pens and take back the original pin is changeless, after using red pens and to touch the grid G to take back the original pin, if the multimeter reading from larger value to 0, the black pens and pick up for the source S, red pens and answered the dra

18、in is D. Using the table red stroke, the grid G is effective, indicating that the tube is P channel fet.Check for good or badMeasuring the positive and reverse resistance values between any two feet of the field effect, using the multimeter R x 1k or R x 10k. In normal time, the positive and reverse

19、 resistance values of the other pins (G and D, G and S) should be infinite, except the positive and the source are smaller. If the measured resistance value between a polar close to 0, then the tube has broken down.In addition, still can use trigger grid (p-channel fet with red pens and trigger, N c

20、hannel field effect works black pens and trigger) method to judge whether the field should be damaged. If the trigger is valid (the positive and reverse resistance of D and S is 0 when the grid G is triggered), it is determined that the tube is performing well.Estimate their amplificationN channel V

21、MOS field effect transistor, available in the black marker of multimeter (R x 1k). The multimeter indicates that the resistance is larger. Contact the grid G with your fingers. If the induction signal is added to the human body, a large deflection of the multimeter needle indicates that the tube has

22、 strong amplification capability. If the needle does not move or the deflection is not large, it indicates that the tube has no amplification ability or amplification ability.It should be noted that this method does not apply to a few VMOS high power field effect transistors with built-in protection diodes. Fiel