Testing methods for controllable silicon

Testing methods for controllable silicon

1. Detection of unidirectional thyristor

Multimeter selection resistor R × Step 1, use red and black probes to measure the forward and reverse resistance between any two pins until a pair of pins with a reading of tens of ohms is found. At this time, the pin connected to the black pen is the control pole G, the pin connected to the red pen is the cathode K, and the other empty pin is the anode A. At this point, connect the black lead to the determined anode A, and the red lead to the cathode K. At this point, the pointer of the multimeter should not move. Instantly short circuit anode A and control electrode G with a short wire. At this point, the multimeter pointer should deflect to the right, and the resistance reading should be around 10 ohms. When anode A is connected to the black probe and cathode K is connected to the red probe, the pointer of the multimeter deflects, indicating that the unidirectional thyristor has been broken down and damaged.

2. Detection of bidirectional thyristor

Use a multimeter to measure resistance R × Measure the forward and reverse resistance of any two pins using two red and black probes in 1st gear, and the results show that two sets of readings are infinite. If a group is tens of ohms, the two pins connected to the red and black lead of that group are the first anode A1 and the control electrode G, and the other empty pin is the second anode A2. After determining the A and G poles, carefully measure the forward and reverse resistance between A1 and G poles. The black lead with a relatively small reading is connected to the first anode A1, while the red lead is connected to the control pole G. Connect the black lead to the determined second anode A2 and the red lead to the first anode A1. At this time, the multimeter pointer should not deflect and the resistance value should be infinite. Then use a short wire to momentarily short circuit the A2 and G poles, and apply a forward trigger voltage to the G pole. The resistance value between A2 and A1 is about 10 ohms. Subsequently, disconnect the A2 and G short wires, and the multimeter reading should remain around 10 ohms. Swap the red and black lead wires, with the red lead connected to the second anode A2 and the black lead connected to the first anode A1. Similarly, the pointer of the multimeter should not deflect and the resistance value should be infinite. Use a short wire to momentarily short the A2 and G poles again, and apply a negative triggering voltage to the G pole. The resistance value between A1 and A2 is also about 10 ohms. Subsequently, disconnect the short circuit between A2 and G poles, and the multimeter reading should remain unchanged at around 10 ohms. Compliance with the above rules indicates that the tested bidirectional thyristor is not damaged and the polarity judgment of the three pins is correct.

It is necessary to connect a 1.5V Dry cell in series in the multimeter black pen to improve the trigger voltage when detecting that the high-power thyristor is grounded.