Norton gremlins

Discussion in 'Old's Cool' started by Sergeant Joe, Oct 18, 2012.

  1. Sergeant Joe

    Sergeant Joe Sitrep=Snafu

    Joined:
    Mar 8, 2009
    Oddometer:
    244
    Location:
    Tasmania,Australia
    G'day guys,
    I have a 1971 Norton Commando with a gremlin in the 'lektrizity.
    The owner who gave it to me to sus out the problem could not get it to even light up off the keystart, no istrument lights, headlight ect and would blow fuse after fuse????
    Well I did all my circuit tests and traced wire circuits for the whole bike.
    In the end I found that if I disconected the rectifier and the Zenner diaod Blue/Brown wires the keystart would operate again and the red dashlight would light up, even the headlight would work!
    So now I know it's one of these two buggers, however if I clip one or the other back on it's spade connecter.....off gose all lights and the fuse gets real hot or blows.
    So this would make me think it's both the Rectifier & the Zenner Dioad that are stuffed:huh.
    Has anyone out there seen this before?
    It's like when I connect one or the other or both up it robs the bike of current from the ignition barrel up to the front half of the bike! at the same time overloading the circuit at the back of the bike (around the battery area).
    any ideas would be welcome thanks guys.:D
    #1
  2. Voltaire

    Voltaire Bored Of The Rings

    Joined:
    Jun 4, 2011
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    1,751
    Location:
    Auckland,New Zealand
    #2
  3. Sergeant Joe

    Sergeant Joe Sitrep=Snafu

    Joined:
    Mar 8, 2009
    Oddometer:
    244
    Location:
    Tasmania,Australia
    Sorry, it's not the regulator thats a hassel as the bike has Boyer electronic ignition in it. it's the recterfier that bolts just to the LHS of where the rear of the main frame tube ends. the other one (Zenner dioad) is down near the foot rest on the RHS of the bike.

    but thanks for the links they are good stuff:clap.
    #3
  4. Bill Harris

    Bill Harris Confirmed Curmudgeon

    Joined:
    Sep 20, 2008
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    backwoods Alabama
    Sorry, Sarge, you've hit the wrong beachead. This be the BMW Airheads section... you might get a wider audience over in Old's Cool (down the hall, second door to the right). :D

    --Bill
    #4
  5. Steve G.

    Steve G. Long timer

    Joined:
    Oct 30, 2004
    Oddometer:
    7,457
    Location:
    West is the Best

    Of course we all know it's positive earth, so I won't even mention that.
    I would get rid of the zener diodes and the bridge recifier at the earliest opportunity. There are many better options available today, most the same amount of money, and more reliable.
    http://www.walridge.com/section/view/
    #5
  6. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    2,508
    The rectifier has at least three "spade" connectors on it. Which one are you pulling?

    The rectifier and zener are both noted for causing shorts. I gave up on them when I found I could no longer buy a zener diode that either did not short or actually limit charging voltage. There are several encapsulated rectifier/regulators available; I like the Podtronics because it looks like it belongs on these bikes and is reasonably priced.
    #6