1. Detection of ordinary Darlington tube
The inside of a conventional Darlington tube is composed of a collector of two or more transistors connected together, and a plurality of emitter junctions are included between the base b and the emitter e. The test can be measured using the multimeter's R&TImes; 1 kΩ or R&TImes; 10 kΩ.
Measure the positive and negative resistance values ​​between the electrodes of the Darlington tube. Normally, the forward resistance value between the collector c and the base b (when the NPN tube is measured, the black meter is connected to the base b; when the PNP tube is measured, the black meter is connected to the collector c) and the common silicon transistor is electrically connected. The forward resistance values ​​are similar, ranging from 3 to 10 kΩ, and the reverse resistance value is infinite. The forward resistance value between the emitter e and the base b (the black meter is connected to the base b when measuring the NPN tube; the black meter is connected to the emitter e when the PNP tube is measured) is between the collector c and the base b The forward resistance value is 2 to 3 times, and the reverse resistance value is infinite. The positive and negative resistance values ​​between the collector c and the emitter e should be close to infinity. If the positive and negative resistance values ​​between the c and e poles of the Darlington tube or the positive and negative resistance values ​​between the b and e poles, b and c poles are close to 0, the tube has been broken down. damage. If the positive and negative resistance values ​​between the b and e poles of the Darlington tube are measured to be infinite, the tube is open circuit damaged.
2. Detection of high-power Darlington tube
High-power Darlington has added a protection circuit consisting of a freewheeling diode and a bleeder resistor on the basis of the ordinary Darlington tube. The measurement should pay attention to the influence of these components on the measurement data.
Use the multimeter R&TImes; 1 kΩ or R&TImes; 10 kΩ to measure the forward and reverse resistance of the Darlington tube collector junction (between collector c and base b). In normal time, the forward resistance value (when the base of the NPN tube is connected to the black test lead) should be small, 1 to 10 kΩ, and the reverse resistance value should be close to infinity. If the measured values ​​of the positive and negative resistances of the collector are small or infinite, the tube has been short-circuited or open-circuit damaged.
Use the multimeter R × 100 Ω file to measure the positive and negative resistance between the emitter e and the base b of the Darlington tube. The normal values ​​are several hundred ohms to several thousand ohms. The specific data is based on b and e. The resistance values ​​of the two resistors are different. For example, the positive and reverse resistance values ​​of the high-power Darlington tube b and e poles of the BU932R and MJ10025 are about 600 Ω, if measured. A resistance of 0 or infinity indicates that the tube under test is damaged.
The forward and reverse resistance values ​​between the emitter e and the collector c of the Darlington tube are measured with a multimeter R x l kΩ or R × 10 kΩ. Normally, the forward resistance value (when measuring the NPN tube, the black meter is connected to the emitter e, the red meter is connected to the collector c; when the PNP tube is measured, the black meter is connected to the collector c, the red meter is connected to the emitter e) should be 5~ 15 kΩ (BU 932R is 7 kΩ), the reverse resistance value should be infinite, otherwise the c, e pole (or diode) breakdown or open circuit damage of the tube.
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