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Canon K30321 / Delta EADP-24NP

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    Canon K30321 / Delta EADP-24NP

    Used in a Canon printer to provide 24V supply.

    Printer was dead and I could measure no voltage out of PS so I opened it up. Was presented with a main electrolytic which had electrolyte crystals coming from its base (and a leg which subsequently fell off), a blown 2A fuse, 2 power diodes short and the main switching FET was short.

    Replaced all components and expected it to work. With no load I get ~8VDC which I assume to be correct for standby mode. However, plug in the printer and the main FET blows short circuit and takes out diodes and fuse. (I've since put an incandescent lamp in series with the input supply to limit short circuit current and replaced all components and repeated. Again it took out the main FET again once connected to the printer.)

    I'm substituting the FET with a 13NM60N, which by my reading of the specs, should be a suitable substitute for the 2SK3567 used in the original circuit.

    The schematic I've posted is not exactly the same as my circuit but close enough to understand how the circuit works.

    Any suggestions much appreciated.

    (By the way, if anyone is wondering why I'm bothering to repair this PS, the owner of the printer is very attached to it. Obviously she is very comfortable in how she drives her old printer from her computer. Furthermore, it came in via a"Remakery" we operate. A not-for-profit volunteer group trying to save electrical gear from ending up in landfill.)
    Attached Files

    #2
    Re: Canon K30321 / Delta EADP-24NP

    Here are the spec sheets for those two FETs
    Attached Files

    Comment


      #3
      Re: Canon K30321 / Delta EADP-24NP

      Hi. Dkneyle.

      In my humble opinion and without knowing that adapter, I do not think that 8vdc is correct although it is possible since the mosfet in the output has connection with the TL431.

      You checked the diodes and capacitors on the secondary side.

      If you send a 3vdc signal to the center pin according to what is specified in the diagram, will the 24vdc no-load source be activated?

      Did you check that on the printer side the PCB is not short ?, As when connecting the adapter the components were burned again.

      Greetings.

      Comment


        #4
        Re: Canon K30321 / Delta EADP-24NP

        If the fet was shorted, they usually open the source resistor, check R7 also, that small cap C4 and also C8 are very likely bad, check the voltage across C4, it should be about 25+ volts, which is regulated to 22 volts by the transistor and its 22v base zener.
        Try turning it on with a 3v button cell battery, you could load the 24 volts with a couple 14 volt lamps in series, automotive 1156.

        Comment


          #5
          Re: Canon K30321 / Delta EADP-24NP

          The schematic I've posted her (for a different Canon power supply) and the actual board I have are actually quite different once I started to analyse the circuit.
          Anyway, there is a zener marked ZD33 on the board. It sits on the source of the FET and appears to be in parallel with the current sensing resistor. Anyway, it is short circuit and looks like it overheated by some discoloration on the board. I can't read its type number no matter what mag lens I use; I think it's been burned to the point of being unrecognisable. Anyone want to guess what value it might be?
          At this point I'm giving up, and have ordered a replacement supply from China.
          Thought I'd just get to the end of this post in case anyone follows it and wants to chase down the same fault in the future.
          Last edited by dkneyle; 12-19-2018, 12:50 AM.

          Comment


            #6
            Re: Canon K30321 / Delta EADP-24NP

            Whats the number on the ic? is it a fa5528 like the schematic? or maybe a DAP8E ? If I had to guess it would be around 5.1 volt zener its there to protect the IS input from voltage spikes.
            Last edited by R_J; 12-19-2018, 10:27 AM.

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              #7
              Re: Canon K30321 / Delta EADP-24NP

              The SMT controller chip is marked 1219A6. I've attached the spec sheet for this device.

              (I'm just following up on this thread even though I've ordered a replacement from China. Might help someone in the future?)
              Attached Files

              Comment


                #8
                Re: Canon K30321 / Delta EADP-24NP

                Recently i had to fix this PSU with the same syptoms as the OP described, in my case the main cap was leaky, fuse was gone and 3 diodes of the bridgde recifier were damaged (2 shorted and the third open), main mosfet was Drain-Source shorted and ZD33 was shorted too, i've replaced it with a 5.1v zener based on it's markigs, also D5 had failed open, after all these replacements the PSU seems to work just fine so far.

                Comment


                  #9
                  Re: Canon K30321 / Delta EADP-24NP

                  Thanks Captain for giving us a good breakdown of what parts need to be replaced when this SMPS fails.

                  Comment

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