High-power Darlington tube inspection

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High-power Darlington tube inspection

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.

The forward and reverse resistance values of the Darlington tube collector junction (between collector c and base b) are measured with a multimeter R × 1 kΩ or R × 10 kΩ. 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 of the two resistors is 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