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Extending primary leads on OT?

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  • Extending primary leads on OT?

    I have an Eden E300T 300 watt tube head that had a blown OT. I got a decent deal on an NOS SVT CL transformer (no replacements for original that I could find). One problem I have is that the lead for the OT primary CT is not long enough, by about 5 or 6 inches. Is there a way to safely extend this lead or do I now have two expensive boat anchors?

    Here is a picture of the SVT OT, the primary CT is the red/white wire:
    Click image for larger version

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    Thanks in advance,
    Greg

  • #2
    Sure, you can solder extensions to the wires. The primaries carry 120vAC, so the wire insulation and shrink tubing needs to capably handle that much voltage (not a tall order at all).

    Wait...you said "primary CT" which doesn't make sense to me. Only the secondaries have CTs.
    --
    I build and repair guitar amps
    http://amps.monkeymatic.com

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    • #3
      Originally posted by xtian View Post
      Sure, you can solder extensions to the wires. The primaries carry 120vAC, so the wire insulation and shrink tubing needs to capably handle that much voltage (not a tall order at all).

      Wait...you said "primary CT" which doesn't make sense to me. Only the secondaries have CTs.
      It's an OT.
      - Own Opinions Only -

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      • #4
        Originally posted by xtian View Post
        Sure, you can solder extensions to the wires. The primaries carry 120vAC, so the wire insulation and shrink tubing needs to capably handle that much voltage (not a tall order at all).

        Wait...you said "primary CT" which doesn't make sense to me. Only the secondaries have CTs.
        This is an output transformer. By CT I mean the lead that feeds the B+ voltage to the primary side of the OT. On this amp this is about 650V.

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        • #5
          It is a WIRE, of course you can extend it. It is just a wire. SPlice a longer wire to it and cover the splice with some heat shrink tubing. If you want to be cool about it, use the same color wire.
          Education is what you're left with after you have forgotten what you have learned.

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          • #6
            I stand whatevered.
            --
            I build and repair guitar amps
            http://amps.monkeymatic.com

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            • #7
              Originally posted by Enzo View Post
              It is a WIRE, of course you can extend it. It is just a wire. SPlice a longer wire to it and cover the splice with some heat shrink tubing. If you want to be cool about it, use the same color wire.
              Mostly didn't know if I needed to use HV wire and connectors, and if I should solder splice to the existing wire (and if a certain type of splice is best) or leave the existing connector and use make a male/female pigtail, etc. Looking around my bins most of the wire seems to only be rated 300V, have some that says 300/500, but am not up on wire ratings.
              Last edited by glebert; 04-09-2020, 08:56 PM.

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              • #8
                Originally posted by glebert View Post
                Mostly didn't know if I needed to use HV wire and connectors, and if I should solder splice to the existing wire (and if a certain type of splice is best) or leave the existing connector and use make a male/female pigtail, etc. Looking around my bins most of the wire seems to only be rated 300V, have some that says 300/500, but am not up on wire ratings.
                You could always add heat shrink all the way over your additional 300V rated hook wire used to extend the C/T lead. Alpha FIT 221 heat shrink carries a voltage rating of 600V, so that would certainly take care of the voltage rating.
                Logic is an organized way of going wrong with confidence

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                • #9
                  I don't really care for the idea of using the existing connector, but you could use a crimp type butt connector, then heatshrink over. Or solder splice w/heatshrink as mentioned.
                  Originally posted by Enzo
                  I have a sign in my shop that says, "Never think up reasons not to check something."


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                  • #10
                    I can't imagine anything more reliable than a standard Western Union splice, soldered and tubed.
                    Education is what you're left with after you have forgotten what you have learned.

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                    • #11
                      Originally posted by Enzo View Post
                      I can't imagine anything more reliable than a standard Western Union splice, soldered and tubed.
                      Yea your not using it like a rope should be good enough for a lifetime.
                      https://en.wikipedia.org/wiki/Western_Union_splice
                      nosaj
                      soldering stuff that's broken, breaking stuff that works, Yeah!

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                      • #12
                        I don't even take it THAT far. It's not a tether or any sort of physical support or stress point. I usually just spread the stranding on each end I want to splice and then sort of insert them into each other, if you get my meaning. Then I squeeze down the spread ends and give a little twist to tighten it up. Solder and add shrink tube... It makes for a skinnier, smoother looking splice if appearances matter. Otherwise the Western Union splice is certainly more reliable.
                        "Take two placebos, works twice as well." Enzo

                        "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                        "If you're not interested in opinions and the experience of others, why even start a thread?
                        You can't just expect consent." Helmholtz

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                        • #13
                          Originally posted by nosaj View Post
                          Yea your not using it like a rope should be good enough for a lifetime.
                          https://en.wikipedia.org/wiki/Western_Union_splice
                          nosaj
                          Well, I learned something new today. I always called it "twisting two wires together"



                          edit: but upon reflection, I can well imagine back in the telegraph days there needed to be a standard for the splices, and plenty of 'em - I doubt there weren't too many 1000-mile-long rolls of telegraph wire being spun 150 years ago.

                          edit: I see the WU splice is meant to be a structural member, the wire solid core and stiff!
                          Last edited by eschertron; 04-10-2020, 06:33 PM.
                          If it still won't get loud enough, it's probably broken. - Steve Conner
                          If the thing works, stop fixing it. - Enzo
                          We need more chaos in music, in art... I'm here to make it. - Justin Thomas
                          MANY things in human experience can be easily differentiated, yet *impossible* to express as a measurement. - Juan Fahey

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                          • #14
                            For what it is worth, to me twisting two wires together is a pigtail splice.
                            Education is what you're left with after you have forgotten what you have learned.

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                            • #15
                              This is all really helpful to me. My splice game has always been weak because I would do it so infrequently and was never shown different ways to splice. I definitely used the term pigtail improperly above because to me the pigtail was the section of wire that was added, not the wire joint itself.

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