Diode Test Range In Digital Multimeter

By on November 27, 2012

I'm not sure about you but when testing diode I do not use the diode test range found in digital multimeter. I knew many repairers are using this diode test range to test on diodes. For your information the test result sometimes could misled you. This means a leaky diode could still be tested good using the diode test range.

diode test range

 

I have encountered many bad diodes that was tested good using the diode test range but failed when tested it using analog meter set to x 10 K ohm. I have done a test on quite a number of digital meters (even the branded one too like Fluke and Greenlee) and yet the result was the same. Due to this for the past many years I've no longer using diode test range to check on diodes. 

Likes(27)Dislikes(0)

41 Comments

  1. Bruno

    November 27, 2012 at 3:48 am

    Hi Jestine!
     
    Have you tried testing them on a Fluke on ohm range? I have seen some that show leakage when tested on resistance.
     
    Regards,
    Bruno

    Likes(0)Dislikes(0)
    • Jestine Yong

      November 27, 2012 at 3:51 am

      Hi Bruno,

      No because the output voltage from the fluke ohm range is still very low as compare to the output voltage from the analog meter.

      Jestine

      Likes(1)Dislikes(0)
      • marq bartlett

        December 4, 2013 at 2:06 pm

        Dear Sir,

        I am curious about what you mean about the voltage used on analog meters compared to digital when testing diodes. Thank you, I always appreciate your insight, and I have enjoyed the e-books you have produced. Is issued address in your testing components, if so, let me know so I can get it.

        Likes(0)Dislikes(0)
        • Jestine Yong

          December 4, 2013 at 8:25 pm

          HI Marq,

          The output voltage from analogue meter is higher than the digital meter. This means a leaky diode can be found using analog meter. As for the testing ebook you can buy it from http://www.testingelectroniccomponents.com

          Jestine

          Likes(1)Dislikes(0)
  2. Bradley Brake

    November 27, 2012 at 4:41 pm

    Good tip, Jestine .I use an analog meter for testing transistors for the same reason.

    Likes(3)Dislikes(0)
    • Jestine Yong

      November 27, 2012 at 6:58 pm

      Hi Bradley,
      Yes the analog meter is a better choice to test transistors, diodes and etc

      Jestine

      Likes(2)Dislikes(0)
  3. Waleed Rishmawi

    November 28, 2012 at 12:18 am

    i have fluke 112 that usese 9 volts battery and I have not seen it fail in any way. I always test diodes with the diode setting and always worked.

    Likes(0)Dislikes(0)
    • Jestine Yong

      November 28, 2012 at 6:27 am

      HI Waleed,

      Ok noted.what is the output voltage of the diode range in Fluke 112?

      Jestine

      Likes(1)Dislikes(0)
  4. Daud Asi

    November 28, 2012 at 7:20 am

    I agreed with the opinion of Mr Jestine Yong 

    Likes(1)Dislikes(0)
  5. Mohammed Kasim

    November 28, 2012 at 10:10 am

    will it harm the diode when it is in forward biased condition

    Likes(1)Dislikes(0)
    • Jestine Yong

      November 29, 2012 at 12:17 am

      Hi Mohammed,

      No because a diode usually is rated more than 50 volt.

      Jestine

      Likes(2)Dislikes(0)
  6. Waleed Rishmawi

    November 28, 2012 at 11:50 am

    I do not know the output voltage of the diode setting in the fluke 112. Ihow can I know it?

    Likes(0)Dislikes(0)
    • Jestine Yong

      November 29, 2012 at 12:16 am

      Hi Waleed,

      Just use another voltmeter and you can test the output of the diode range.

      Jestine

      Likes(2)Dislikes(0)
      • Frank Washock

        November 14, 2013 at 12:12 am

        Hello Jestine, How would I send you an e-mail? I sent 2 to 2 different addresses and have not heard back. It was a tube amp power supply issue I thought would be simple I sent some screen shots of the signal from my O=scope. Thanks, Frank

        Likes(0)Dislikes(0)
        • Jestine Yong

          November 14, 2013 at 10:26 am

          Hi Frank,

          Sorry i did not get your email. Or could you use other email account to send

          Jestine

          Likes(0)Dislikes(0)
  7. Waleed Rishmawi

    November 29, 2012 at 12:10 am

    I down loaded the user manual of the fluke 112 and it said that the output of the diode is 2.2 volts.
     

    Likes(1)Dislikes(0)
  8. Waleed Rishmawi

    November 29, 2012 at 12:14 am

    to be exact, 2,200 volts.

    Likes(0)Dislikes(0)
  9. Naeem

    November 29, 2012 at 3:19 am

    Hi Jestine,
    I have DWM (Kipco DT830D) but i has not any 10k range. Can i use one of these range provided by meter as 200,2000 and 20k ohm range for the diode testing purpose
    Regards
    Naeem

    Likes(0)Dislikes(0)
    • Jestine Yong

      November 29, 2012 at 7:02 am

      HI Naeem,

      No you can't because the output voltage from the meter is still low as compare to analog meter.

      Jestine

      Likes(1)Dislikes(0)
  10. Waleed Rishmawi

    November 30, 2012 at 11:54 pm

    I am still in usa. once I go back I will do that. thanks
     

    Likes(0)Dislikes(0)
  11. Naeem

    December 4, 2012 at 3:49 am

    Hi Jestine,
    I have a tv device (SUNWIN XJ230L,2004 made).My device having picture problem.Picture is zig-ziagged or some like saw-tooth vertically over both the edges of the screen.I'm suspecting some smd's ceramics capacitors in the circuit board but dont khow where.Besides there is nothing any marked rating on smd caps. Would u pls help/hint me about  tracing to cure this  typ of fault . THnkx in advance.
    Regards
    Naeem

    Likes(0)Dislikes(0)
    • Jestine Yong

      December 4, 2012 at 7:09 am

      Hi Naeem,

      Please send in the picture to jestineyong(at)electronicrepairguide.com (at) means @

      Jestine

      Likes(0)Dislikes(0)
  12. Zivai

    December 5, 2012 at 3:23 am

    Hi Jestine
    I remember testing the diodes on a DVD player's mainboard using diode mode and they tested OK but the dvd player would not power up. So I decided to change them anyway since I could not think of anything else, and the DVD player powered up! I had always wondered why the diodes tested good. Now I know and thanks for the information!

    Likes(3)Dislikes(0)
    • Jestine Yong

      December 10, 2012 at 4:18 am

      HI Zivai,

      This similar case had happened to me many times when i was troubleshooting the vertical output of Monitor. They checked good but failed when you power it on.

      Jestine

      Likes(1)Dislikes(0)
  13. Romeo

    December 5, 2012 at 8:10 am

    Hi Jestine,
    I just want to know what software have you use in taking pictures of circuits or components as they look very clear. Is it photoshop or anythingelse?
    Regards,
    Romeo

    Likes(2)Dislikes(0)
    • Jestine Yong

      December 10, 2012 at 4:08 am

      HI Romeo,

      It was taken by a normal digital camera that has the Macro mode. Then I used Paint to edit the photos.

      Jestine

      Likes(3)Dislikes(0)
  14. karl_atienza

    May 24, 2013 at 4:57 pm

    I used the analog tester all the time for the same reason as yours. However, but as a former semicon test guy, ICs normally have a suppression diode per pins and referenced to the IC's GND pin (like a common anode). It is connected as reverse bias. This is used to protect the IC from ESD but you cannot see this in the datasheet.

    The first part of testing the IC in the factory is Open/Short. This is done before testing other important test parameters. The test is like a diode and it will produce a measurement of around ~0.5V to 0.6V. You can check this using the diode test in any IC. Since this diode is in reverse bias position, the positive pin of the DMM must be connected to the GND pin of the IC and the negative to the other pins. You must have the datasheet for the pin outs in order to locate which is the GND pin for there are ICs that have multiple GND pins. THIS TEST IS ONLY GOOD FOR FINDING OPEN/SHORTED IC PINS.

    Likes(0)Dislikes(0)
    • Jestine Yong

      May 25, 2013 at 6:18 pm

      HI Karl,

      Wow! This is interesting. Thanks a lot.

      Jestine

      Likes(0)Dislikes(0)
  15. Abdul Haleem

    September 17, 2013 at 5:32 pm

    Yes, DMM may not be reliable in testing diode but still we can use diode range for a quick check of shorted diodes. One trick with DMM I found to check for a leaky diode (Reverse test leads) is to use Ohms Range. Although most diodes show a reading in Mega Ohms when reverse biased at DMM's Ohms range a leaky diode will show low Ohms reading comparatively. You folks can give it a try and let's know if I'm right.

    Likes(1)Dislikes(0)
    • Jestine Yong

      September 17, 2013 at 9:03 pm

      HI Abdul,

      Thanks for the comment.

      Jestine

      Likes(0)Dislikes(0)
  16. rafael beringuela

    September 24, 2013 at 6:29 pm

    excellent that is true , i encounter also same thing.thanks

    Likes(0)Dislikes(0)
  17. jim

    September 29, 2013 at 8:47 pm

    I am more in cb radio can you help me with that.

    Likes(0)Dislikes(0)
    • Jestine Yong

      September 29, 2013 at 9:28 pm

      HI Jim,

      Sorry no info on CB radio.

      Jestine

      Likes(0)Dislikes(0)
      • Ashwini

        October 1, 2013 at 5:02 pm

        Hiii

        Mr. justine, as per you told the diode range is not perfect but sometimes for IC checking if we are using diode range on multimeter. Is is possibal means IC showing OK on diode range but it is not.

        Likes(0)Dislikes(0)
        • Jestine Yong

          October 2, 2013 at 9:03 am

          Hi Ashwini,

          Multimeter diode range can be used to check on those IC pins but it is not 100% to assume it is ok. The best is to power up the ic and test out the waveform.

          Jestine

          Likes(1)Dislikes(0)
  18. jacob

    October 2, 2013 at 7:20 am

    Thats a tip Jestine,now i know why i fail most of the time,its really important to know how to test right to get right results,
    thanks

    Likes(0)Dislikes(0)
    • Jestine Yong

      October 2, 2013 at 8:58 am

      HI Jacob,

      You are right.

      Jestine

      Likes(0)Dislikes(0)
  19. david

    October 10, 2013 at 9:56 pm

    Hello I m currently working on a power supply for a computer monitor which has no power .Although i tested the fuse which came back positive there is still no power so i tested all components which came back ok except the main transformer in the board but it might not be that .I know that a transformer can not be replace except if you need to find the voltage and current .How do you think i can work this out with not power

    Likes(0)Dislikes(0)
    • Jestine Yong

      October 11, 2013 at 9:33 am

      Hi David,

      Have you checked the secondary side diodes? If one shorted there will be no power. In your case, did the power ic get any dc supply voltage?

      Jestine

      Likes(1)Dislikes(0)
  20. Md. Shahin Reza

    November 28, 2013 at 3:11 pm

    Hi Jestine,
    How to get your electronics repair manual pdf.

    Thanks,
    Md. Shahin Reza

    Likes(0)Dislikes(0)
    • Jestine Yong

      November 28, 2013 at 5:42 pm

      Hi Md.Shahin,

      I have just sent an email to you. Please check your email.

      Thanks.

      Jestine

      Likes(0)Dislikes(0)

Leave a Reply

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