Help with some old electric fencers

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  • canadaboy25
    What is normal?
    • May 2013
    • 509
    • Canada

    #1

    Help with some old electric fencers

    So I know that this forum is more for tech stuff but I'm going to go ahead and post.

    I've go these two old Holdem model 57 electric fencers and neither one of them work. One is older than the other but from what I can tell the wiring is exactly the same.

    None of the lights on either unit light up when plugged in and on and I have checked all of the fuses.

    These units say "clips weeds" on them and they have a removable "chopper" module (see pictures). What are these "choppers" even for? From what I can tell, three of them are the same. One is newer and the other two are older looking ones. From what I can make out on the writing, all three modules are the same. There is also one "mystery" module. It has no markings on the outside and it is about three times heaver than the other three.

    My main questions are, what are these "choppers", how can I test them, and how can I test all of the other parts of the unit?

    I haven't bothered to draw out a wiring schematic yet but if it would be helpful I can make one.

    One last thing is that I am not asking everyone to come and tell me that this is a terrible idea and all that other jazz about it not being safe. I am aware of the dangers and I accept the risks. I also know how to be safe and protect myself from danger, just in case anyone was going to go off on me about it!

    Thanks!
    Attached Files
    canadaboy25

    -Sometimes the light at the end of a tunnel is an on-coming train
  • stj
    Great Sage 齊天大聖
    • Dec 2009
    • 31003
    • Albion

    #2
    Re: Help with some old electric fencers

    oh jesus - dont play with those!!

    it's a current-limited high voltage generator.
    the can probably contains an oscillator that is replaceable incase you overload and kill it by shorting the output.
    does it list the output voltage or current anywhere?
    it has a 2core cable, but i can see the case needs to be earthed because there is a spark-gap on it.

    Comment

    • goontron
      5000!
      • Dec 2011
      • 4108
      • US

      #3
      Re: Help with some old electric fencers

      open one up.
      Things I've fixed: anything from semis to crappy Chinese $2 radios, and now an IoT Dildo....

      "Dude, this is Wyoming, i hopped on and sent 'er. No fucking around." -- Me

      Excuse me while i do something dangerous


      You must have a sad, sad boring life if you hate on people harmlessly enjoying life with an animal costume.

      Sometimes you need to break shit to fix it.... Thats why my lawnmower doesn't have a deadman switch or engine brake anymore

      Follow the white rabbit.

      Comment

      • canadaboy25
        What is normal?
        • May 2013
        • 509
        • Canada

        #4
        Re: Help with some old electric fencers

        Originally posted by stj
        oh jesus - dont play with those!!

        it's a current-limited high voltage generator.
        the can probably contains an oscillator that is replaceable incase you overload and kill it by shorting the output.
        does it list the output voltage or current anywhere?
        it has a 2core cable, but i can see the case needs to be earthed because there is a spark-gap on it.
        I've looked over the thing and I can't find any output ratings.

        Yea the case does get earthed and the fence connects to a terminal on the bottom.


        Originally posted by goontron
        open one up.
        They are both opened...
        canadaboy25

        -Sometimes the light at the end of a tunnel is an on-coming train

        Comment

        • goontron
          5000!
          • Dec 2011
          • 4108
          • US

          #5
          Re: Help with some old electric fencers

          Originally posted by canadaboy25

          They are both opened...
          a chopper.
          Things I've fixed: anything from semis to crappy Chinese $2 radios, and now an IoT Dildo....

          "Dude, this is Wyoming, i hopped on and sent 'er. No fucking around." -- Me

          Excuse me while i do something dangerous


          You must have a sad, sad boring life if you hate on people harmlessly enjoying life with an animal costume.

          Sometimes you need to break shit to fix it.... Thats why my lawnmower doesn't have a deadman switch or engine brake anymore

          Follow the white rabbit.

          Comment

          • canadaboy25
            What is normal?
            • May 2013
            • 509
            • Canada

            #6
            Re: Help with some old electric fencers

            Originally posted by goontron
            a chopper.
            Ahh yes, I should have seen that!

            Before I open it up, what would be inside there? Any fluids or gasses?
            Last edited by canadaboy25; 01-30-2015, 10:11 PM.
            canadaboy25

            -Sometimes the light at the end of a tunnel is an on-coming train

            Comment

            • Sparkey55
              Badcaps Legend
              • Jan 2010
              • 1523
              • USA

              #7
              Re: Help with some old electric fencers

              Originally posted by canadaboy25
              Ahh yes, I should have seen that!

              Before I open it up, what would be inside there? Any fluids or gasses?
              The chopper is used to control the duty cycle of the ac power to the primary of the transformer incase of an sustained abnormal overload on the high voltage secondary winding.

              Comment

              • stj
                Great Sage 齊天大聖
                • Dec 2009
                • 31003
                • Albion

                #8
                Re: Help with some old electric fencers

                the answer your actually looking for is that it should be safe, it's not a gas or liquid container.

                Comment

                • canadaboy25
                  What is normal?
                  • May 2013
                  • 509
                  • Canada

                  #9
                  Re: Help with some old electric fencers

                  Well I've traced it around and from what I can tell the "chopper" is a bridge rectifier.

                  I'll have to wait until tomorrow to cut into it because it is welded shut.
                  canadaboy25

                  -Sometimes the light at the end of a tunnel is an on-coming train

                  Comment

                  • stj
                    Great Sage 齊天大聖
                    • Dec 2009
                    • 31003
                    • Albion

                    #10
                    Re: Help with some old electric fencers

                    use side-cutters to rip the folded edge open at the base.

                    Comment

                    • canadaboy25
                      What is normal?
                      • May 2013
                      • 509
                      • Canada

                      #11
                      Re: Help with some old electric fencers

                      Well I cut into one of the choppers and it wasn't a rectifier like I originally thought.

                      It looks to be more like a switch or something. Two of the pins are shorted together. The piece of metal connecting them broken so I patched it up with some solder and tried the fencer again but it still didn't work. On the top of the chopper module it says allow time for it to warm up, so would I need to leave it plugged in a long time before it will turn on? It seems unlikely. One of the pins isn't even connected to anything and the last pin goes to some sort of inductor.

                      It seems like a switch but since the two prongs are already shorted, what world the purpose be?
                      Attached Files
                      canadaboy25

                      -Sometimes the light at the end of a tunnel is an on-coming train

                      Comment

                      • Sparkey55
                        Badcaps Legend
                        • Jan 2010
                        • 1523
                        • USA

                        #12
                        Re: Help with some old electric fencers

                        Originally posted by canadaboy25
                        Well I cut into one of the choppers and it wasn't a rectifier like I originally thought.

                        It looks to be more like a switch or something. Two of the pins are shorted together. The piece of metal connecting them broken so I patched it up with some solder and tried the fencer again but it still didn't work. On the top of the chopper module it says allow time for it to warm up, so would I need to leave it plugged in a long time before it will turn on? It seems unlikely. One of the pins isn't even connected to anything and the last pin goes to some sort of inductor.

                        It seems like a switch but since the two prongs are already shorted, what world the purpose be?
                        Current flows thru the small coil that is wrapped around the two pieces of bi-metal contacts which inturn makes contact with the other screw adjustable contact. When enough current flows to heat the bi-metal spring it bends enough to open the contacts, cools down, closes contacts. Rinse and repeat. A simple over current duty cycle limiter just as I stated in an earlier post.
                        Last edited by Sparkey55; 01-31-2015, 11:53 AM.

                        Comment

                        • Sparkey55
                          Badcaps Legend
                          • Jan 2010
                          • 1523
                          • USA

                          #13
                          Re: Help with some old electric fencers

                          Originally posted by canadaboy25
                          Well I cut into one of the choppers and it wasn't a rectifier like I originally thought.

                          It looks to be more like a switch or something. Two of the pins are shorted together. The piece of metal connecting them broken so I patched it up with some solder and tried the fencer again but it still didn't work. On the top of the chopper module it says allow time for it to warm up, so would I need to leave it plugged in a long time before it will turn on? It seems unlikely. One of the pins isn't even connected to anything and the last pin goes to some sort of inductor.

                          It seems like a switch but since the two prongs are already shorted, what world the purpose be?
                          Keep in mind that in order for the chopper to work properly the metal can needs to be reinstalled otherwise the bi-metal switch will not heat up within working paramenters as it was design for. A lot can go wrong with those, burned out heating element, worn contacts, cold solder joints, etc.

                          Comment

                          • canadaboy25
                            What is normal?
                            • May 2013
                            • 509
                            • Canada

                            #14
                            Re: Help with some old electric fencers

                            Well now that I fixed that chopper the newer fencer lights flash and work properly.

                            The older one doesn't work because the capacitors are wrecked.

                            The problem I'm having now is that the spark is very weak.
                            canadaboy25

                            -Sometimes the light at the end of a tunnel is an on-coming train

                            Comment

                            • Sparkey55
                              Badcaps Legend
                              • Jan 2010
                              • 1523
                              • USA

                              #15
                              Re: Help with some old electric fencers

                              Originally posted by canadaboy25
                              Well now that I fixed that chopper the newer fencer lights flash and work properly.

                              The older one doesn't work because the capacitors are wrecked.

                              The problem I'm having now is that the spark is very weak.
                              Does not need to be a strong spark to kill grass and weeds. The output might be just around 2KV or less. Not a bug zapper or cow zapper.

                              Comment

                              • stj
                                Great Sage 齊天大聖
                                • Dec 2009
                                • 31003
                                • Albion

                                #16
                                Re: Help with some old electric fencers

                                recap it.
                                and remember your playing with a weapon designed to hurt things over several miles away.

                                Comment

                                • stj
                                  Great Sage 齊天大聖
                                  • Dec 2009
                                  • 31003
                                  • Albion

                                  #17
                                  Re: Help with some old electric fencers

                                  Originally posted by Sparkey55
                                  Does not need to be a strong spark to kill grass and weeds. The output might be just around 2KV or less. Not a bug zapper or cow zapper.
                                  most of those devices output 5-6Kv
                                  and it IS a cow / sheep / fox / intruder zapper.

                                  Comment

                                  • canadaboy25
                                    What is normal?
                                    • May 2013
                                    • 509
                                    • Canada

                                    #18
                                    Re: Help with some old electric fencers

                                    Well the reason the original owner had given them to me was because one wasn't working, but also because the other wasn't shocking as strong as it used to. That's the reason that he liked it, because it shocked so hard.

                                    Is it possible for the transformer to weaken over time?
                                    canadaboy25

                                    -Sometimes the light at the end of a tunnel is an on-coming train

                                    Comment

                                    • stj
                                      Great Sage 齊天大聖
                                      • Dec 2009
                                      • 31003
                                      • Albion

                                      #19
                                      Re: Help with some old electric fencers

                                      no, it's just a pair of coils - unless one has shorted windings.
                                      but caps age and resistors can change value

                                      btw, these things work through the earth, if you have very dry weather they dont work so well.
                                      and you need a very good groundspike to hook it up to.
                                      .
                                      Last edited by stj; 01-31-2015, 02:30 PM.

                                      Comment

                                      • canadaboy25
                                        What is normal?
                                        • May 2013
                                        • 509
                                        • Canada

                                        #20
                                        Re: Help with some old electric fencers

                                        Well there is only one resistor and it is only hooked up to the mains power indicator light to limit the voltage. The two caps have on lead shorted to ground and the other lead on both of them go to two different prongs on the chopper.

                                        I am just shorting a screwdriver between the hot and ground terminals. The spark used to arc much further that it does now.
                                        canadaboy25

                                        -Sometimes the light at the end of a tunnel is an on-coming train

                                        Comment

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