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Zener diode failure

Discussion in 'Norton Commando Motorcycles (Classic)' started by daveh, Mar 21, 2010.

  1. daveh

    daveh

    Joined:
    Jan 22, 2008
    The Zener diode failed today, while I was strobe timing the bike, causing a short circuit. I checked this by isolating the Zener, which is probably the original. I now have to think of either fitting a new Zener or fitting a system that dispenses with the Zener. I have a standard Lucas two wire alternator. What would be the best way to go from here? Advice would be gratefully received!

    Dave
     
  2. JimC

    JimC

    Joined:
    Oct 12, 2007
    Run with a halogen headlight on at all times and you can forget about a zener. Since the alternator can't keep up, you won't cook the battery. The other alternative is to look at this mishap as being fortuitous. Now you can get rid of the Lucas rectifier and Zener and replace with a more modern Podtronics rectifier/regulator. All in one sweet package.
     
  3. slupdawg

    slupdawg

    Joined:
    Jul 10, 2008
    :D
     
  4. JimC

    JimC

    Joined:
    Oct 12, 2007
    Before someone jumps on me, let me amend my earlier post. I realize we have some long distance touring Norton riders. Having the zener disconnected MAY overcharge the battery with sustained highway running. I have run without a zener for quite some time (short runs around town) and still need to charge the battery occasionally. I've not encountered any problems from high voltage alternator output. This is with a stock, single phase alternator. I suppose it would be prudent to check what voltage your alternator is putting out.
     
  5. daveparry

    daveparry

    Joined:
    Jul 4, 2009
    Did you inadvertently connect the battery the wrong way round Dave, reversed polarity is the usual cause of the Zenner going s/c!
    I can recommend the electronic rectifier/regulator as has been suggested already,
    regards,
    Dave.
     
  6. daveh

    daveh

    Joined:
    Jan 22, 2008
    Jim, advice appreciated, thanks. I was lucky it didn't fail far from home, although if that did happen, I could have disconnected the Zener and ridden home with the headlight on, as you suggested. Looks like the Podtronics unit is the way to go, then.

    Dave
     
  7. daveh

    daveh

    Joined:
    Jan 22, 2008
    Dave, no the battery is connected the right way round (and I still have positive earth), so I know it wasn't me! Maybe it was because I was revving it to 5000 rpm at standstill to strobe time the engine that finished it? I guess 37 years is not too bad for the life of any electrical component ... Glad you think well of the electronic reg/rec. I will order one tomorrow.

    Dave
     
  8. Keith1069

    Keith1069

    Joined:
    Jan 10, 2005
    Ditto to the electronics. I fitted one of Paul Goffs unbranded parts for my 2 wire and it stopped the battery needing a monthly top up.
     
  9. Don Tovey

    Don Tovey

    Joined:
    Jan 2, 2009
    Hi Dave,
    ive got a 72 750 Interstate.
    My 1st zenor diode failed a number of years ago on a run.
    I got a new one & charged the battery & had no trouble again with it.
    Now ive got a boyer power box & boyer electronic ignition & no need for a Zenior & a couple of other old electrical bits.
    Mine starts 1st kick usually & runs fine. I'm happy with the boyer power box. The only reason I got the boyer power box was because I got a new wireing loom & there were no connections for the zenor & other defunct electrical bits.
    The power box is available from Norton Owners club, or any Dealers supplying older british bike spares usually.
    Ive only got the original 2 wire alternator on mine.
    The boyer is only one of a few replacements for the zenor but i'm sure most of them do the job well enough.
    I paid £70 for my Boyer power box.
    Best of luck,
    Cheers Don
     
  10. daveh

    daveh

    Joined:
    Jan 22, 2008
    Hi Don, thanks for the tip. This morning, I decided I would go for the Podtronics regulator/rectifier, which I ordered from Burton Bike Bits (£49). I am hoping that I will get it in the post by the end of the week. I have heard good things about the Boyer as well. A friend will be lending me his Zener to tide me over next weekend if the parcel is late! Now that the weather is better, I want to get the old girl back on the road!

    Dave
     

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