How to use a multimeter to judge the quality of thyristors
1. Check if the multimeter settings are correct
Place the multimeter in the resistance measurement position and ensure that the range is appropriate. The resistance measurement range should be selected as the smallest. For example, on a digital multimeter, a range of 200 ohms can be selected.
2. View test screen
The screen should display 'OL', indicating that the circuit has not been measured yet.
3. Test thyristor
Place the thyristor in the test clamp, with one end connected to the cathode and the other end connected to the anode. During this process, the anode must first be connected to the gate of the thyristor. Connect the clamp of the multimeter to the gate of the thyristor. Check the test screen. If the screen displays "OL", it indicates that the thyristor is normal. If the screen is within the numerical range, further testing is required.
4. Test the on resistance of the thyristor
Place the thyristor in the test clamp, connect the anode and cathode to the test clamp, and connect the clamp to the gate. At this point, the test screen should display a very small value. If the test screen is still blank, it means that the thyristor has been damaged.
5. Test the reverse resistance of the thyristor
Place the thyristor in the test clamp, connect the gate and anode together, and then connect the clamp to the cathode. The test screen should display a value greater than OL. If the test screen is still blank, it means that the thyristor has been damaged.
6. Test the forward voltage of the thyristor
Place the thyristor in the test clamp, connect the clamp to the cathode and gate of the thyristor, and then connect the anode to the power supply. At this point, the test screen should display a very small value. If the test screen is still blank, it means that the thyristor has been damaged.
