Fluctuating/jumping voltage on the board

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  • myth77
    Badcaps Veteran
    • Feb 2017
    • 380
    • Croatia
    #1

    Fluctuating/jumping voltage on the board

    I am quite new at fixing boards and have one question that i couldnt find answer on the internet...What smd part/parts could cause jumping voltages on motherboard, and how to find them? I have this asus board that were shorted to the ground, i replaced dead 19v mosfets and now board is not shorted...but...when i use multimeter (with power on) on 19v net it is showing 19v stable (not fluctuating)...but on 5v,3v and 1v net the readings are jumping...on 1vsus it is jumping every second 0,23v, 0,78v, 1,2v, 0,75v, 0,27 v....and so on...same on the 5v and 3 v nets...Is it voltage regulator? mosfet? or? I tried to check with finger is anything heating a lot..but i couldnt find it...


    And one more thing... the multimeter is working fine (not broken) i test it on other working boards and voltage readings are stable.
    Last edited by myth77; 08-07-2019, 03:31 AM.
    Tags: None
    • Techtiger
      Badcaps Legend
      • Oct 2014
      • 1601
      • france
      #2
      Re: Fluctuating/jumping voltage on the board

      Upload the Schematic, remove one PAD of 5/3V each Coil PL and see whether the voltage is jumping maybe you have a Bad regulator IC 5/3V

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