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find faulty compnent on ATX power supply

Discussion in 'Troubleshooting and Repair' started by pharaon, Sep 1, 2021.

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  1. pharaon

    pharaon

    392
    6
    Oct 28, 2014
    it's ATX power supply i'm working on
    the issue is in 5V output, it drop to 3V when i connect it to 12V pc fan, and the fan keep kicking without spin
    i hear fry sound from this side of main transformer but can't detect exactly which component making the sound or responsible for not delivering enough current to 5V line output
    [​IMG][/url]
     
  2. davenn

    davenn Moderator

    13,877
    1,964
    Sep 5, 2009

    Honestly, they are just not worth the time and frustration trying to repair them
     
  3. pharaon

    pharaon

    392
    6
    Oct 28, 2014
    i'm doing it for learning purposes
     
  4. Bluejets

    Bluejets

    5,029
    1,050
    Oct 5, 2014
    Lesson 1.......it's not worth the time and frustration trying to repair them.
    There are many avenues to learn electronics and the overall best ( as it always was) is to study the theory.
    Then one can apply newfound knowledge correctly.

    Starting point possibility...... https://www.power-supplies.com.au/files/mean-well-user-technical-manual.pdf
     
    Last edited: Sep 2, 2021
  5. pharaon

    pharaon

    392
    6
    Oct 28, 2014
    in the below image to the right is the connector of cooling fan, it doesn't start and voltage at connectors drop from 12 to 3 when the fan is connected, i back traced it and removed smd NPN transistor that is shorted and this is it's datasheet
    http://elektrikaetoprosto.ru/ebc849c.html
    i replaced it with STC945 NPN transistor since i couldn't find smd one but the same issue still exist.
    also ther's those two gray and yellow wires connected to the heat sink beside cooling fan tracks .
    what could be the reason for this issue

    [​IMG][/url]
    [​IMG][/url]
    [​IMG][/url]
     
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