Method one dials the pointer multimeter to the "rx1k" file, and the ESC is zeroed. The field effect is the same side of the word, from left to right: G (Gate), D (drain), S (source). The Black Watch pen is connected to the D-Pole, the red pen is connected to the S-pole, at this time, the multimeter hands should not move, and then swap the pen, then test, at this time, the multimeter hands should be swinging to the right. With the pointer multimeter measurement, the G-pole, and the remaining two poles, no matter how the two-meter pen to be measured, the multimeter pointer should be fixed. Method Two will dial the digital multimeter to the "diode" file, that is, the buzzer file. Black Table pen to the D-pole, red table pen to the S-pole, at this time, should display a numeric value, generally for more than 400 Ω to 500ω. Then, to swap the pen, there should be no display, for "1". Then, the Black table pen to the D-Pole, the red pen first to touch the G-pole, and then the red pen to the S-pole, at this time, you will find that the displayed value compared with the original, a lot smaller, generally 100 ω to dozens of ω between. This indicates that the FET has been triggered to pass. At this time, the black table pen to the S pole, the red table pen to the D-pole, you will find that there is a numerical display. This shows that the FET is intact. If the results are inconsistent with the above two methods, then the FET is bad. In general, D-pole and S-pole breakdown are more common. Using the "diode" of the digital multimeter, you will hear the sound of the buzzer. The above two methods are suitable for almost any type of field effect tube.
Multimeter Judging the good or bad of field effect tube
