Pingshang Technology teaches you how to test diodes
September 03 11:43:35, 2025
How to Test if a Diode is Good or Bad Using a Multimeter
Testing the condition of a diode is an essential skill for anyone working with electronics. A multimeter is the most common tool used for this purpose. Before starting, make sure your multimeter is set to the RX1K resistance range (avoid using RX1 as it may damage the diode). Next, short the red and black test leads together to calibrate the meter to zero ohms.
**1. Forward Bias Test**
To check the forward characteristics of the diode, connect the black lead (negative) to the anode (positive terminal) of the diode, and the red lead (positive) to the cathode (negative terminal). If the needle doesn’t move all the way to 0 but stops somewhere in the middle, that reading represents the forward resistance. The lower the forward resistance, the better the diode. However, if the resistance reads 0, the diode is likely shorted and damaged. On the other hand, if the resistance is close to infinity, the diode is open and not functioning. In both cases, the diode should be replaced.
**2. Reverse Bias Test**
Now, reverse the connections: place the red lead on the anode and the black lead on the cathode. In a good diode, the needle should point to infinity or a very high resistance value. This indicates that the diode is blocking current in the reverse direction, which is its normal behavior. If the needle moves significantly, the diode is faulty and needs to be replaced.
By performing these two simple tests, you can determine whether a diode is in good condition or not. Always make sure the multimeter is properly set and calibrated before testing. This method is reliable and widely used by technicians and hobbyists alike.
For more information on electronics and circuit testing, visit [http://news.chinawj.com.cn](http://news.chinawj.com.cn)