Another way to detect IGBT tubes with a pointer multimeter
①Judge the polarity. Put the multimeter in the RXl kQ setting, connect the black test lead to a certain pin, and connect the red test lead to the other two pins respectively. Observe the measured data: reverse the two test leads, and use the red test lead to fix it to the original black test lead. On the connected pin, the black test lead is connected to the other two pins. If the resistance measured twice is infinite, the pin connected to the fixed test lead is the gate. Use a multimeter to measure the remaining two pins. If the measured resistance value is infinite, the measured resistance value is smaller after swapping the test leads: In a measurement with a smaller resistance value, the red test lead is connected to the drain and the black test lead is connected to the drain. source.
②Judge good or bad. Set the multimeter to the R×1kΩ range, connect the black test lead to the drain of the IGBT tube, and the red test lead to the source. At this time, the multimeter's indication should be infinity. Touch the gate and drain with your fingers at the same time. At this time, the IGBT tube is triggered to conduct, and the pointer of the multimeter swings in the direction of smaller resistance, and can stabilize at a certain value. Then touch the source and gate with your fingers at the same time. At this time, the IGBT tube is blocked and the pointer of the multimeter returns to infinity. At this point, you can judge that the IGBT is good.
Why is there no response when measuring capacitance with a multimeter?
One, the capacitor has been disconnected. We know that multimeters measure capacitance, and they are mainly used as DC power supplies and ammeters. When the capacitor is connected to the DC power circuit, the capacitor is in a charging state, and the ammeter will have an indication (that is, the multimeter will respond). If the multimeter does not respond at this time, there is only one possibility, that is, the capacitor has been disconnected (that is, open circuit).
Second, the battery in the multimeter is exhausted. This problem is easy to check. Turn the multimeter to the ohm setting (any setting will do) and touch the red and black test leads. If the multimeter has no indication or the pointer does not move (analog multimeter), it means the battery has been exhausted. If the multimeter has an indication or the pointer returns to zero, it means the battery is still charged.
