Beginners can use a multimeter to test the performance of diodes in amateur conditions. Before the test, first, switch the switch of the multimeter to the RX1K position of the ohm gear (be careful not to use the RX1 gear to avoid excessive current and burn the diode), and then short-circuit the red and black test leads to perform ohmic zero adjustments.
1. Positive characteristic test
Touch the black lead of the multimeter (positive in the watch) to the anode of the diode, and the red lead (negative in the watch) to the cathode of the diode. If the hand is not set to 0 but stopped at the middle of the dial, the resistance at this time is the forward resistance of the diode. Generally, the smaller the forward resistance, the better. If the forward resistance is 0, it indicates that the die is short-circuit damaged. If the forward resistance is close to infinity, it means that the die is open. Neither short-circuit nor open-circuit pipes can be used.
2. Reverse characteristic test
If you touch the red lead of the universal watch to the anode of the diode and the black lead to the cathode of the diode, if the needle is at or near infinity, the tube is qualified.