1940 Johnson HS-10 Mag

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  • February 15, 2017 at 8:51 pm #6356
    Mumbles
    Participant

      This is the mag style with the two brushes and a brass grounding plate on a Bakelite plate inside the flywheel. Common sense tells me one half of the dual firing coil will send juice down one wire to the plug and at the same time the other half will send it to one of the brushes and up thru the brass plate to ground.

      The problem is, I don’t have any continuity between the brass plate and the flywheel and I’m assuming there should be. Is that correct? If so, that means drilling the tiny rivets out to remove the Bakelite plate to get at the back side of the plate and flywheel? Dang!

      Can anyone confirm the new wiring is correct? I just copied what was there before.

      Thanks in advance!

      February 15, 2017 at 9:35 pm #53072
      Mumbles
      Participant

        I couldn’t wait and drilled out the rivets. There’s signs it has definitely been arcing in there! I did manage to find a page on this mag and there’s supposed to be a contact spring in the small hole in the Bakelite plate. The hole measured 3/32" so that’s really small! Would anyone have a spare spring in their pile or a suggestion where to find one that size?
        Thanks!

        February 15, 2017 at 11:17 pm #53076
        david-bartlett
        Participant

          Jim,

          How about a Spring like on the shifters on the OMC motors of the 50’s?

          February 15, 2017 at 11:46 pm #53079
          willyboy
          Participant

            Would the spring out of a pen work if you cut it down to fit?

            February 16, 2017 at 1:41 am #53088
            Mumbles
            Participant

              Thanks, but I already tried those and they were way too big! I have an assortment of small springs and thought I might have one but they were also too big. Anyway, after pulling my hair out for a while, I started thinking, what about the little spring in the top of the Merc floats. Bingo, problem solved! I save those in case I might need one sometime and that time was today!

              After trimming to length, it fit right in. It’s a good thing I had a couple extra as I lost two of them and don’t have any more new floats handy. The continuity is good now so I’ll finish it in the morning after a good sleep. ☺

              February 16, 2017 at 1:45 am #53090
              david-bartlett
              Participant

                Well done! Old ECK is spinning in his grave.

                February 16, 2017 at 2:12 am #53093
                bob-d
                Participant

                  US Member

                  Jim, if you could post a few shots of how you reinstalled the rivets that would be helpful as well.
                  Thanks.

                  February 16, 2017 at 2:39 am #53098
                  Mumbles
                  Participant

                    I sure will Bob. I’ve been thinking about it but that’s tomorrows project. I sure don’t want to break that brittle unobtainium plate!

                    February 17, 2017 at 5:29 am #53146
                    Mumbles
                    Participant

                      The original hollow rivets are cast into the plate and don’t go all the way thru the plate, as shown in the diagram for the replacement plate so I had to use what was left of the originals. At first I thought I could run a small screw into the rivets to expand them but they weren’t long enough to grip the flywheel so I used some epoxy to hold the plate in. If the epoxy fails, the old rivets and plate could be carefully drilled out to accept new rivets or small bolts. I’m hoping the epoxy works.

                      February 17, 2017 at 2:58 pm #53147
                      jeff-register
                      Participant

                        US Member

                        Jim,
                        Very good job! I too hope the epoxy keeps everything in place. Looking at the grounding or bonding terminal it looks to have been arcing from spring failure. Did you clean the carbon trails before assembly? Wish I was close to examine with a magnifying glass to see what it reveals. My eyes are not as good as they once were so the help is always welcome. Also with your old wire to be soldered get some soldering flux in a small can. Dip the bare end into the flux & heat until the flux bubbles. This will clean the old oxidized layer off the strands & the bare end will accept & bond to the cable before trying to solder to the fragile coil terminal. I had this same problem using phone cable terminating to small parts like transistors & resistors. Dipping into the flux tin & heat really helped with keeping the heat down on the parts.
                        Very interesting how the magneto windings are not in the same space. I see no reason why it wouldn’t function, it just looks odd at first glance. Anyone know of other motors with this magneto? 😀

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