+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Advanced Member level 2
    Points: 3,524, Level: 13
    imranahmed's Avatar
    Join Date
    Dec 2011
    Location
    Karachi,Pakistan
    Posts
    595
    Helped
    2 / 2
    Points
    3,524
    Level
    13

    Reason behind short circuit in SMPS primary side

    Please let me know that why components in primary side in SMPS battery charger damaged i.e bridge rectifier diodes, switching transistor 10N60, current sense resistor 0.5 ohms, optocoupler and UC3842 at the same time.

    What would be a reason behind this failure I repaired three times but same thing occured?
    IMRAN

    •   AltAdvertisment

        
       

  2. #2
    Advanced Member level 5
    Points: 22,270, Level: 36
    barry's Avatar
    Join Date
    Mar 2005
    Location
    California, USA
    Posts
    4,261
    Helped
    943 / 943
    Points
    22,270
    Level
    36

    Re: Reason behind short circuit in SMPS primary side

    Shorted transformer primary


    1 members found this post helpful.

    •   AltAdvertisment

        
       

  3. #3
    Advanced Member level 2
    Points: 3,524, Level: 13
    imranahmed's Avatar
    Join Date
    Dec 2011
    Location
    Karachi,Pakistan
    Posts
    595
    Helped
    2 / 2
    Points
    3,524
    Level
    13

    Re: Reason behind short circuit in SMPS primary side

    How to test primary is shorted or not?

    I test with Ohm meter its resistance shows zero ohms.
    IMRAN



    •   AltAdvertisment

        
       

  4. #4
    Advanced Member level 5
    Points: 22,270, Level: 36
    barry's Avatar
    Join Date
    Mar 2005
    Location
    California, USA
    Posts
    4,261
    Helped
    943 / 943
    Points
    22,270
    Level
    36

    Re: Reason behind short circuit in SMPS primary side

    Transformers are a little difficult to test with an ohmmeter. Did you remove the transformer connections from the circuit? Do you know what the primary D.C. Resistance SHOULD be? It could be very low normally.



  5. #5
    Advanced Member level 4
    Points: 7,261, Level: 20

    Join Date
    Aug 2015
    Posts
    1,130
    Helped
    433 / 433
    Points
    7,261
    Level
    20

    Re: Reason behind short circuit in SMPS primary side

    output diodes shorted, sec winding shorted, gate drive to mosfet faulty, the list goes on ...



    •   AltAdvertisment

        
       

  6. #6
    Newbie level 5
    Points: 1,698, Level: 9
    Achievements:
    7 years registered

    Join Date
    Sep 2009
    Location
    Romania
    Posts
    8
    Helped
    0 / 0
    Points
    1,698
    Level
    9

    Re: Reason behind short circuit in SMPS primary side

    It is understood that after each repair it worked for a while. In cases of repeated defects, all soldering must be checked with a magnifying glass . In the transistor's drain there is a group of components including one or two capacitors. These caps must be carefully measured or better replaced with some of the same type and voltage. The transformer fails in extremely rare cases. Up-load here the electric diagram to comment in detail. Did you check that the electrolytic cap follow the bridge is not o/c ?



--[[ ]]--