Cap Advice Please

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  • sparkyuiop
    New Member
    • May 2008
    • 8
    #1

    Cap Advice Please

    I have a bad cap in a PSU and want to know if I can swap it with a slightly lower voltage one. I know this is not recommended generally but do you think it would work or be worth the risk trying?
    Thanks in advance.

    OLD: 420v / 120uf / 105c - REPLACE WITH: 400V / 120uf / 105c
    Tags: None
    • sparkyuiop
      New Member
      • May 2008
      • 8
      #2
      Re: Cap Advice Please

      Well got no answer so I did it anyway and it works fine

        Comment

        • momaka
          master hoarder
          • May 2008
          • 12170
          • Bulgaria
          #3
          Re: Cap Advice Please

          Originally posted by sparkyuiop
          Well got no answer so I did it anyway and it works fine
          Well, expecting a reply in under 43 minutes is quite unrealistic on a forum. A few hours is somewhat more reasonable.
          Anyways...

          Before you go with a lower voltage cap, it's always a good idea to check the voltage on he original capacitor first to see if a cap with a lower voltage rating can be used.
          Just because the 400v cap is working right now doesn't mean much. If the voltage in the circuit is very close or slightly above what the cap can tolerate, then the cap may eventually die.
          Last edited by momaka; 06-07-2011, 12:10 AM.

            Comment

            • sparkyuiop
              New Member
              • May 2008
              • 8
              #4
              Re: Cap Advice Please

              Thanks momaka. I always been an impatient lad!

              The originals were 420v and replaced with 400v. Still working but I heed your point.

              Phill.

                Comment

                • momaka
                  master hoarder
                  • May 2008
                  • 12170
                  • Bulgaria
                  #5
                  Re: Cap Advice Please

                  Good to hear it's still working. No need to worry about it anymore, I guess . (otherwise, you would have known by now). Most likely the manufacturer used the 420v cap to get better ESR and ripple current. I would say the voltage on it is probably closer to 385 VDC.

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