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Is Bigger Diode Can Be Used As Replacement?

By on December 23, 2009

When you are searching for an equivalent diode, a bigger diode (in term of physical size) does not necessary mean that it will last and can be used for replacement. You must know the spec of the original diode in order to get the replacement diode. A big diode could have small spec and it will immediately blow when the power is On. Assuming you can’t get the spec of the original diode, what you can do is to use the highest spec of the replacement diode. But first, you must know at what circuit you found the diode. For Main line AC rectification, a general purpose diode with a few hundreds volts spec and 3 amp is adequate for this task. If the diode is in the output of SMPS, then you have to use a Schottky diode or Ultra fast recovery diode. A uf5404 that have 3 amp with 400V spec 50ns is very good¬† for many of the consumer electronics SMPS. If you found any small diode part number in the primary side of SMPS and the size of the diode is like the 1n4007 then use the UF40007 as replacement.

Many times it is not easy to find the exact replacement, if you could get the standard diode equivalent part number that can be used on many circuits then you will save lots of time. You may try different part numbers on different circuits so that in the future, if you come across part number that you have not seen before then i guess your own finding would be a great help to you.

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5 Comments

  1. behzad

    December 23, 2009 at 9:08 am

    hello jestine

    this a real good subject diodes . let me tell you what is my problem
    i checked evrything in the board and now i reached to a crystal small type diode nothing is written on body no diagram but the diode is suspected what do u recommend to do now?
    rgrds
    beh

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  2. admin

    December 23, 2009 at 11:46 pm

    Hi behzad,
    Try to use 1n4148 diode.

    Jestine

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  3. behzad

    December 24, 2009 at 12:47 am

    hello jestine

    thank you so much i try 1n4148 diode now everything is ok
    the set is working again
    regrdes
    beh

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  4. Beejadhur Prikeshsing

    September 3, 2018 at 3:25 pm

    Hello!! I do have a diode in a suppression circuit on a boat starter. The original diode got into pieces due to a faulty relay. The approx diameter is 3.5mm can you please help me for a replacement as per the manufacturer i must but the diode for 50USD and they will not tell me the ref of the diode.
    Thanks
    Ashiv

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    • Jestine Yong

      September 4, 2018 at 7:50 am

      Hi Ashiv,
      Sorry I do not have the info for diode used in boat suppression circuit. We deals mainly on consumer electronics products. Perhaps you can visit the link below and contact them:

      https://marinehowto.com/voltage-transients-in-marine-electrical-systems/

      Jestine

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