Testing Zener Diode - Fast and Simple WayTo Accurately Test Zener Diode 


Analog multimeter is the right meter to test a zener diode. First, search from your favorite data book  what is the zener diode code represent. I highly recommend Philip ECG semiconductor master replacement guide. When you have determined the zener diode voltage, it is easy to check with your meter to see if it leak, open or shorted. For your information, a zener diode with 2.4 volt to 12 volt should have two readings when measure with an analogue meter set to times 10K ohm range. But these readings is not shorted reading!


Let me explain, when you place your probes across the zener diode of 2.4 volt using the times 10 k ohm range, one way will show a full scale reading (red probe to cathode and black probe to anode) which mean the needle will moved towards the 0 ohms scale while the other way (black probe to cathode and red probe to anode) the needle will point to around 2- 5 ohms! If both ways of testing and the needle point to the 0 ohm scale then the zener diode consider shorted. When you measure a 6.8 volt zener diode, as usual one way will point to zero ohms while the other way will show a higher resistance which is in the 20 to 50 ohms. These are the characteristic of a good working zener diode.


When you measure a zener diode from 13 volt and above, it should have only one reading using the times 10 K ohms range. That's mean the red probe to the cathode and black probe to the anode. Reversing the probe should not show any reading. If the result shows two readings then the zener diode is shorted or have leakage. Start taking out zener diode from your component's rack and do some testing, compare a good zener diode and a shorted one. It would'nt take you a long time to become a  pro in accurately testing a zener diode. One more thing, only replace a zener diode with the same or higher wattage. If possible use the exact voltage.


test zener diode


Author By : Jestine Yong



Repairing Articles
Free Repairing Tips
Download Service Manual
TFT LCD Display Equivalents
Repairing Bookstore
Other Resources
Contact Us
Free Subscribe Now
Site Map

LCD TV Repair

Plasma TV Repair

Projection Tv Repair

Learn Basic Electronic

Computer Repair Course

Learn Laptop Repair

CRT Tv Repair Course

LCD Monitor Repair ebook

How to testing Electronic Components like a Pro!

Power Supply Repair Guide- all types of SMPS


1 Feb 2007

Many thanks!  I have
downloaded the file and
will - hopefully - now be
able to fix the screen.
Like your website -
very helpful...
thanks again.
- Mike

31 Dec 2006

thank you for this
great site that i
found what i
search about.

15 Jan 2008

Thank you very
much for your
excellent site!
I know there would
be lots of people
around the world
who will appreciate
your very neat,
well-organised site.
-Matt Straford

DONATE Help the P2U

If you find my free stuff useful, why not leave me a little something with PayPal.

Donations are greatly appreciated, and help with the costs of providing FREE service manual & server fees.