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65 Echoplex Repair

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  • 65 Echoplex Repair

    Chasing down some extraneous noise in the EP2. Got with my friend Echoplex repair guru Pete out in LA and had some fun chasing it down. What a rats nest cluster inside. Found a cold solder joint on one cap and then replaced an old black beauty cap on the oscillator circuit that was failing.

    Best part is learning hands on with a foreign circuit and overall "amp" theory that is totally new to me.

    Don't be scared of grabbing an old tape echo. Easy to work on.









    www.CelticAmplifiers.com

    "You can't save everybody, everybody don't wanna be saved."

  • #2
    Re: 65 Echoplex Repair

    Cool!

    Bill
    When you've had budget guitars for a number of years, you may find that your old instrument is holding you back. A quality guitar can inspire you to write great songs, improve your understanding of the Gdim chord while in the Lydian Mode, cure the heartbreak of cystic acne--and help you find true love in the process.

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    • #3
      Re: 65 Echoplex Repair

      Originally posted by Scott_F View Post
      Don't be scared of grabbing an old tape echo. Easy to work on.

      Ssaaayyyyzzz you.

      Comment


      • #4
        Re: 65 Echoplex Repair

        Originally posted by beaubrummels View Post
        Ssaaayyyyzzz you.
        Chop stick it just like an amp till you find the offender.


        www.CelticAmplifiers.com

        "You can't save everybody, everybody don't wanna be saved."

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        • #5
          Re: 65 Echoplex Repair

          I love this stuff. The transmitters and receivers we currently use out here are 60's technology/design. Unfortunately they'll be replaced shortly and the opportunity to get in a properly fix stuff will go with them.


          Do what I do. Hold tight and pretend it's a plan!

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          • #6
            Re: 65 Echoplex Repair

            Planned obsolescence.


            www.CelticAmplifiers.com

            "You can't save everybody, everybody don't wanna be saved."

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            • #7
              Re: 65 Echoplex Repair

              Next assignment is to figure out what the "coil trap" does.


              www.CelticAmplifiers.com

              "You can't save everybody, everybody don't wanna be saved."

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              • #8
                Re: 65 Echoplex Repair

                what praytell is the pink thing next to the 6c4?

                my deluxe reverb crapped out last night at a gig but since its not a modern amp, ill throw it on the bench today and my guess is within the hour figure out and hopefully fix it. if it was a modern amp or god forbid digital id be looking for another amp.

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                • #9
                  Re: 65 Echoplex Repair

                  Originally posted by jeremy View Post
                  what praytell is the pink thing next to the 6c4?

                  my deluxe reverb crapped out last night at a gig but since its not a modern amp, ill throw it on the bench today and my guess is within the hour figure out and hopefully fix it. if it was a modern amp or god forbid digital id be looking for another amp.
                  Looks like an inductor or an air core transformer of some sort. I suppose it would depend on how it is wired.

                  Here's a manual with schematics: http://www.vintagewindings.com/gen%2...x%20Manual.pdf

                  Looks like it's part of an oscillator circuit.
                  Last edited by trevorus; 04-11-2017, 09:55 AM.
                  Originally posted by crusty philtrum
                  ...Gimme a call when it's time to take 'em out. I don't have a gun, but i have a very sharp pointy stick and enough negativity to take out a small country...
                  Originally posted by Securb
                  The only blackmachine I care about is sitting in my jeans.

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                  • #10
                    Re: 65 Echoplex Repair

                    I asked similar question over at TGP. https://www.thegearpage.net/board/in...#post-23911055


                    www.CelticAmplifiers.com

                    "You can't save everybody, everybody don't wanna be saved."

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                    • #11
                      Re: 65 Echoplex Repair

                      Originally posted by trevorus View Post
                      Looks like an inductor or an air core transformer of some sort. I suppose it would depend on how it is wired.

                      Here's a manual with schematics: http://www.vintagewindings.com/gen%2...x%20Manual.pdf

                      Looks like it's part of an oscillator circuit.
                      It's the bias oscillator. You need a bias signal to get the sound onto the tape. It also feeds the erase head signal. I can't quite figure the bias removal in the circuit but some times the play back head contributes to that. There will also be Pre-empasis and de-emphasis EQ circuitry in there. Getting sound onto tape is a mildly convoluted process.

                      _ https://en.wikipedia.org/wiki/Tape_bias -
                      Last edited by GoldenVulture; 04-15-2017, 04:12 AM.
                      sigpic

                      - http://www.soundclick.com/bands/defa...?bandID=804435 -
                      - https://soundcloud.com/mr-ds-bigband/tracks -

                      Warning: May contain traces of NUTS

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                      • #12
                        Re: 65 Echoplex Repair

                        My thoughts. If the tape is working , don't screw with it.


                        www.CelticAmplifiers.com

                        "You can't save everybody, everybody don't wanna be saved."

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