Hitachi J100 series inverter

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  • R_J
    Badcaps Legend
    • Jun 2012
    • 9535
    • Canada
    #1

    Hitachi J100 series inverter

    I am trying to identify a diode, Marked "L2 29" the diodes are located across the electrolytic capaacitors, which should make them like tvs diodes, but they also seem to be used as the main rectifiers for the voltage going to the caps. from the switching transformer.
    The diode thats bad (shorted & broke) was across a also shorted 1000uf 10 volt electrolytic.
    These diodes are used other places on the board, some have 24 volts across them.

    There is also one other similar diode marked "V6 22" (its ok)

    without any diode the unit comes on but voltage to the 24 volt fan is too high.
    I tried a 33 volt zener and the unit would not work, acted like there was a short, I placed two 33 volt zeners in series where the diode goes and the unit powers up with the proper 24 volts to the fan

    Just checking to see if anyone else has seen these before.
    Thanks
    Attached Files
    Last edited by R_J; 09-29-2017, 04:52 PM.
    Tags: None
    • redwire
      Badcaps Legend
      • Dec 2010
      • 3907
      • Canada
      #2
      Re: Hitachi J100 series inverter

      I think the diode is a Sanken part like EL02Z is 200V 1.5A 40nsec rectifier diode, as part of a voltage-doubler perhaps.
      I would use any 1A ultrafast-recovery diode like UF4004

      PSU voltage regulation seems to be CMP HA17903 comparator driving opto PC1. Your diode probably powers the IC, so the PSU will go full-tilt unless PC1 activated.

      Might have two failures, the PSU voltage too high and damaging caps, then diode failing.

      DP11 looks blackened. Diode DP2-K by terminal block lead looks arced to.

        Comment

        • R_J
          Badcaps Legend
          • Jun 2012
          • 9535
          • Canada
          #3
          Re: Hitachi J100 series inverter

          I can't put a fast recovery in its place, the power supply will not start up as it sees what amounts to a short, dp11 checks fine, it got discolored when dp9 burnt up,
          DP2 has a bit of corrosion on its cathode but its not used (only comes into play if external resistor is used which its not)
          the inverter seems to work fine with the two zeners in series si suspect its a tvs diode, maybe around 50-60 volt
          I sent an email to Hitachi industrial, we'll see what they say???
          Last edited by R_J; 09-29-2017, 06:29 PM.

            Comment

            • R_J
              Badcaps Legend
              • Jun 2012
              • 9535
              • Canada
              #4
              Re: Hitachi J100 series inverter

              I'm not sure what I did when I put the fast recovery diode in the first time but after checking everything I installed the diode again and its working just fine with a FR157 diode, so it was just a fast recovery diode.
              The cap that shorted was a rubycon 1000/10 volts, the new cap. has 5 volts across it.

                Comment

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