Don't Miss

Another Zener Diode Tester Was Built

By on September 9, 2013

Another Zener diode tester was built by one of my ERG members Mr Orin Fraser from Guyana. The zener diode tester diagram came as a bonus when you purchase the Troubleshooting And Repairing Switch Mode Power Supply Ebook. Check out the photos below:

zener diode tester

zener diode tester

zener diode checker



  1. Antonio

    September 11, 2013 at 3:48 am

    Hello Mr. Jestine Yong, I extend to you and any other person who can help me to resolve a fault on an old CRT TV MIVAR (Italian brand) which has this problem:
    The screen looks green with white lines Retrace and no video image, while the audio is OK.
    If you can kindly tell me in general at what stage should I turn my attention to repair the aforementioned 25-inch CRT television.
    I thank in advance all those who will want to give me advice.
    Antonio Simone

    • Jestine Yong

      September 11, 2013 at 11:11 am

      Hi Antonio,

      It can be shorted tube (green cathode shorted to grid) or it can be the green circuit have problem probably shorted transistor. Try compare the voltage/signal between the green and blue/red circuit. Any differences is the clue for you to trace the problem.


  2. castro luis

    March 26, 2014 at 12:06 pm

    goodnight sir jestine yong, advance my greetings, this is to ask a technical aid. I have a 32 inch LED TV is heard and not seen, I put a lamp behind the screen to see if the picture and gave me cash given image, but the LEDs are good, and the other probe pernden, could use to give me a no clue if incombenientes.
    thank you very much., and I congratulate you for your contributions.
    as I get the diagram diode tester.?

    • Jestine Yong

      March 26, 2014 at 6:05 pm

      HI Castro,

      If the power led is red this could mean the mainboard MCU/flash rom could have problem. As for the zener diode tester diagram, it is part of the bonus package for those who bought the SMPS repair ebook at



Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.