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1958 James Cadet - Positive or Negative Earth?

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1958 James Cadet - Positive or Negative Earth?

Post  emjaydee on Sun Jun 21, 2015 9:34 pm

Hello,
I've almost finished restoring a 1958 James Cadet and I need a little advice. I'm currently rewiring the bike and I notice the earth diode was broken, I would like to know if the bike has a negative or positive earth so I can purchase the right one?

Thanks

emjaydee

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Join date : 2015-04-13

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Villiers wiring

Post  FB vincent on Mon Jun 22, 2015 4:06 pm

emjaydee wrote:Hello,
I've almost finished restoring a 1958 James Cadet and I need a little advice.  I'm currently rewiring the bike and I notice the earth diode was broken, I would like to know if the bike has a negative or positive earth so I can purchase the right one?

Thanks

Per the Villiers 29C and 30C operating instructions, the positive side of the battery is earthed. I presume you are referring to a broken rectifier (which would only have been required with a battery equipped model).

FB vincent

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Re: 1958 James Cadet - Positive or Negative Earth?

Post  emjaydee on Mon Jun 22, 2015 7:03 pm

Thanks for the reply, I'm not sure there was a battery installed to this model.  The earth diode which as broken looks like this:


There are 2 types, a positive and a negative, not sure which one to get, is there anyway of checking?

Thanks

emjaydee

Posts : 4
Join date : 2015-04-13

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Zener diode

Post  piston 197 on Mon Jun 22, 2015 8:23 pm

That's an unusual fitment on a Villiers powered machine ? usually a zener is used to soak up over charge on alternator systems ( usually 12 volt) would not have thought the standard Villiers flywheel magneto was capable of producing an excess charge ?
JH
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piston 197
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Re: 1958 James Cadet - Positive or Negative Earth?

Post  emjaydee on Mon Jun 22, 2015 8:52 pm

When I was stripping the bike down, the wire from the magneto was connect to this diode which was bolted to the body of the bike next to the horn.

Using a voltmeter the voltage ranges from 5 volts at low rev to 12 volts when high revs, which is strange because all the bulbs on the bike are 6v bulbs, surely this would blow them unless this diode reduces it.

What comes out of the magneto, positive or negative?

Thanks

emjaydee

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AC or DC

Post  piston 197 on Tue Jun 23, 2015 6:10 am

The voltage produced by the flywheel will be AC ( alternating current) it only becomes smoothed DC after passing through a rectifier, The earth is then a matter of choice of the manufacturer
JH
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piston 197
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Villiers wiring

Post  FB vincent on Wed Jun 24, 2015 4:36 pm

I suggest you use the forum SEARCH function, since there have been many discussions on the wiring and rectification of the lighting output for Villiers engines. Ignore anything to do with AMC engine wiring (the larger engines have an alternator), the Villiers 30C engine will have the same system as the 8E which was fitted to several FB and James models.

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Re: 1958 James Cadet - Positive or Negative Earth?

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