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Help confirm dead tape head in Maestro Echoplex EP3

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  • Help confirm dead tape head in Maestro Echoplex EP3

    Hi everyone,

    I hope this will be a quick one for someone with experience working on tape echos:

    I've been working for a while now on reviving a beat-up Echoplex EP3, with the main issue being a loss of the erase function.
    A few days ago I finally did some checks on the record/erase head itself, and I might have found the problem: I measured resistance across the coils of the tape head, and while the recording side measures 62.5 ohm, the erase side measures OL, in and out of circuit.

    Before I go ahead and try and find a replacement, could someone confirm that this means the tape head is dead, without a doubt?



    A few points:
    - I've attached a labeled layout of my Echoplex, and the schematic
    - On point 15, I'm measuring only 0.44V (I think I remember reading it should be a lot higher)
    - On point 17, I'm measuring 28V
    - I'd love to open the tape head to check solder connections of the wires, but the assembly seems to be sealed
    - I've checked all electrolytic capacitors, and swapped a few
    - I've cleaned the tape heads with IPA, and recently reloaded the tape cartridge with NOS 8 track tape

    Hope someone can help, finding the issue on the this machine has been driving me crazy!


    ECHOPLEX_OWNER-SERVICE_MANUAL 29.pdf
    Click image for larger version

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  • #2
    Sadly itīs dead.
    Erase heads need significative current through them to create a strong alternating magnetic field which will do the erasing thing, open circuit is a no no.
    To boot, schematic label shows "Erase Head 25 ohm DC"

    But it shouldnīt be hard to find a replacement.
    Juan Manuel Fahey

    Comment


    • #3
      Originally posted by J M Fahey View Post
      Sadly itīs dead.
      Erase heads need significative current through them to create a strong alternating magnetic field which will do the erasing thing, open circuit is a no no.
      To boot, schematic label shows "Erase Head 25 ohm DC"

      But it shouldnīt be hard to find a replacement.
      Thanks a lot for clearing that up, and for the technical explanation, much appreciated!

      I have looked everywhere for a replacement, the only one I could find ships from Australia for around Ģ90 (these combi-heads seem difficult to find).

      Are there other sources for these out there? Maybe old reel-to-reel machines that can be salvaged for a replacement head?
      Or would it be possible to add a separate erase head along the tape path somehow?


      Thanks,
      Joris

      Comment


      • #4
        Click image for larger version

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        This is probably the one you found. If the machine is well maintained this can only add value. Get them to send it regular postage and save a few bob !
        The parts for these things will become harder to find and more expensive.

        https://echofix.com/collections/echo...ord-erase-head
        Last edited by oc disorder; 11-08-2020, 08:51 AM.

        Comment


        • #5
          Originally posted by oc disorder View Post
          This is probably the one you found. If the machine is well maintained this can only add value. Get them to send it regular postage and save a few bob !
          The parts for these things will become harder to find and more expensive.

          https://echofix.com/collections/echo...ord-erase-head
          Yep, that’s the one. You’re right, might be expensive now, but at least the machine will be working again.

          I’ve contacted two surplus stores in the US as well (the tape head is a Nortronics P-A1HC44R), I will report back if I have any luck with that - otherwise it’s gonna be the one from echofix.

          Thanks for your help!

          Comment


          • #6
            Keep it original if you can, but if not possible, erase head position is NOT critical at all.
            As long as it is after playback heads and before recording ones, tape WILL be erased to kill old tata (audio) so new data can be recorded on an "empty" tape.
            Meaning any generic erase head will do, obviously on its own mounting, as long as it is reasonably close in specs.
            Juan Manuel Fahey

            Comment


            • #7
              Originally posted by J M Fahey View Post
              Keep it original if you can, but if not possible, erase head position is NOT critical at all.
              As long as it is after playback heads and before recording ones, tape WILL be erased to kill old tata (audio) so new data can be recorded on an "empty" tape.
              Meaning any generic erase head will do, obviously on its own mounting, as long as it is reasonably close in specs.
              Thanks, that’s good to know! Might be worth trying until I find the original.

              What are the specs to look out for?

              Comment


              • #8
                UPDATE for anyone interested: I received a replacement record/erase head today, ordered from JRF Magnetics in the US, and the Echoplex is up and running again.

                There are still original Nortronics replacement heads out there, and JRF Magnetics seems to be the place, although I did have to enquire directly. Priced similar to others I saw on the web, and cheaper if you're based in the US.

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