How to read the code of zener diode

Many repair engineers and technicians are confused on how to read the zener diode code or marking. There are many types of zener diode's code number indicated on it's body. The shape of a zener diode sometimes can be mistaken to be like a normal signal diode. To differentiate it, is by looking at the code number on it's body- whether it is a zener diode or normal signal diode. Thanks to the manufacturers where their main boards are printed with the word 'ZD' which referred to zener diode and 'D' means a diode. However, from my repair experienced some printed circuit board have the marking of 'D' also can mean zener diode. Don't be confuse because this can misled a repair engineers and technicians into believing a zener diode is actually a diode. We must know or be sensitive about the marking otherwise we would not be able repair the equipment due to wrongly replacing the components!

The only way to distinguish it is by referring the code number printed on the component's body from a semiconductor replacement book. Without semiconductor guide book it is quite difficult to know the actual zener diode voltage. If you do not have the data book you may go to any search engine and type the following code and hope you can get the answer there! A wrong substitution of zener diode number may caused your equipment to be malfunction and sometimes will even blow your equipment. Time and money are wasted due to that we lack of experience of identifying the right zener diode voltage. If you are unable to identify the code, do not worry as this article is here to guide you to successfully find out the zener diode code.5.1=5.1V zener diode 5V1=5.1Volt zener diode12= 12 V zener diode12V= 12 Volt zener diode BZX85C22=22Volt 1 watt zener diode (refer to ECG PHILIPS SEMICONDUCTORS MASTER REPLACEMENT GUIDE) BZY85C22=22Volt 1/2 watt zener diode (refer to ECG PHILIPS SEMICONDUCTORS MASTER REPLACEMENT GUIDE) Note: There is also a part number such as BZVXXXXX where you have to find it from ECG SEMICONDUCTOR DATA BOOK.

1N4746= 18 V 1 watt zener diode (refer to ECG PHILIPS SEMICONDUCTORS MASTER REPLACEMENT GUIDE) 6C2=6.2 V zener diode. (If you look at the zener diode marking it is written as 6C2 READING FROM TOP TO BOTTOM). Don't read from bottom to top otherwise the value you get is 2C6 which you cannot find from data book!                                                                          
I believe many of you will ask this question-how do I get the voltage for the code of 6C2. Still refer to ECG book, you have to search for HZ part number. That's mean instead of finding 6C2, search for HZ6C2 and you
will get the answer! The lowest zener voltage that I came across was 2.4 v and the highest was 200 V 5 watt. The code number and the voltage explained above were from my experienced as a technician.
However if you have other code number that you want to share with other fellow technicians or engineers, you can email me at jestineyong@noahtec.com

Conclusion- Be careful when reading the part number of a zener diode. Don't always assume that a small signal diode is always a zener diode. Carefully observe the marking on the main board and read the zener diode marking refer to the semiconductor data book, preferably ECG SEMICONDUCTOR MASTER REPLACEMENT GUIDE DATA BOOK which you can buy from your local electronic distributors. With the tips that i've given above hope that you will be able to successfully read and get the right zener voltage for repalcement