230VAC PSU connected to 400VAC

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  • electroBriedis
    New Member
    • Aug 2019
    • 4
    • Latvia
    #1

    230VAC PSU connected to 400VAC

    I accidentally connected a 230 VAC to 24 VDC PSU to 400 VAC. After about 5 seconds there was a spark and then the mains circuit breaker tripped. I have added the pictures of how the damage on the PSU looks in the attachments. The PSU's model is PULSE QS10.241.
    I don't have much experience in fixing electronics and no PSUs at all. How should I go about fixing this? The varistor clearly needs to be changed and the big capacitor most likely as well. I don't see anything else visibly damaged, could changing just these 2 parts fix the PSU? Are there any tests that can be done before I connected the PSU to power again?
    Attached Files
    Tags: None
    • stj
      Great Sage 齊天大聖
      • Dec 2009
      • 31015
      • Albion
      #2
      Re: 230VAC PSU connected to 400VAC

      you may be lucky,
      the blue thing is a MOV, a device that gets rid of spikes.
      they suicide themselves in these situations causing the fuse to blow.

      you may get away with a new fuse and MOV.
      the cap is probably o.k. - other than the soot-stain on the side!

      most important though - you have to clean that crap off the board / parts because it can be conductive.
      and i would replace the second MOV in the picture too, it looks like it has a hole in it.
      is the fuse glass, or ceramic? either way the replacement should be ceramic.
      Last edited by stj; 08-08-2019, 01:42 AM.

        Comment

        • redwire
          Badcaps Legend
          • Dec 2010
          • 3907
          • Canada
          #3
          Re: 230VAC PSU connected to 400VAC

          I see molten metal on the PCB, hopefully it was the MOV melting. Not arcing to the cap can. I did not see a burnt NTC anywhere.

          You could carefully cut out the MOV's, replace the fuse and try the PSU. The MOV's are for surge and overvoltage protection and the PSU can run without them for doing a test.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: 230VAC PSU connected to 400VAC

              How about showing us the pictures of the whole board?
              I would check the bridge rectifier, diodes, MOSET's, ect. to see if any of them shorted out.
              You do have proper tools for testing and soldering, correct?
              Never stop learning
              Basic LCD TV and Monitor troubleshooting guides.
              http://www.badcaps.net/forum/showthr...956#post305956

              Voltage Regulator (LDO) testing:
              http://www.badcaps.net/forum/showthr...999#post300999

              Inverter testing using old CFL:
              http://www.badcaps.net/forum/showthr...er+testing+cfl

              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
              http://s807.photobucket.com/user/budm/library/

              TV Factory reset codes listing:
              http://www.badcaps.net/forum/showthread.php?t=24809

                Comment

                • electroBriedis
                  New Member
                  • Aug 2019
                  • 4
                  • Latvia
                  #5
                  Re: 230VAC PSU connected to 400VAC

                  Thank you everyone for your replies! I added more pictures so the board is better visible.
                  To answer your questions:
                  @stj
                  The fuse is ceramic. You can see it in one of the pictures.
                  A complete noob question, but can I try to just pull out the fuse or are fuse holders like this meant to be desoldered to replace the fuse?

                  @budm
                  I have a decent soldering station, solder wick and a multimeter. Do you recommend any other tools?
                  Attached Files

                    Comment

                    • R_J
                      Badcaps Legend
                      • Jun 2012
                      • 9535
                      • Canada
                      #6
                      Re: 230VAC PSU connected to 400VAC

                      That is a pigtail fuse and needs to be unsoldered to be replaced

                        Comment

                        • Per Hansson
                          Super Moderator
                          • Jul 2005
                          • 5895
                          • Sweden
                          #7
                          Re: 230VAC PSU connected to 400VAC

                          After checking the bridge rectifier, diodes, MOSET's, ect for shorts as budm suggested:
                          Replace the fuse with a 60w (or more) incandescent light bulb.
                          If the bulb is lit brightly and does not dim when you power it on the PSU is still shorted...
                          "The one who says it cannot be done should never interrupt the one who is doing it."

                            Comment

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