[Farmall] Turning on the magneto switch on Farmall "H"

Tim Savelle tim.savelle at gmail.com
Sat Mar 13 06:54:45 PST 2010


Thanks.  And also....is there any way to tell if the alternator is charging
the battery?  The amp meter doesn't move off zero when I flip the toggle
switch up and down.



On Thu, Mar 11, 2010 at 8:57 PM, DBigdog <DBigdog at columbus.rr.com> wrote:

> Tim,
>    If you trace the wires from the switch back to the alternator you should
> find one wire connected to the 12 volt + source.  The other wire should be
> attached to the alternator excitation terminal. (marked #1)  Attach the
> diode between the excitation terminal and the 12 volt +  with the striped
> end of the diode connected to the exciter lug.
>    You can get the diode at Radio Shack.  A 1N4001 diode or equivalent will
> do the job.  You can make these connections right on the alternator.
>
>
> ----- Original Message -----
> From: Tim Savelle
> To: Farmall/IHC mailing list
> Sent: Thursday, March 11, 2010 8:30 PM
> Subject: Re: [Farmall] Turning on the magneto switch on Farmall "H"
>
>
> Ok.  Thanks for the info.  How difficult it is to install the diode (or how
> easy would it be for me to install it wrong), and where can I get the
> correct diode of the correct type and size?
>
> On Thu, Mar 11, 2010 at 7:30 PM, DBigdog <DBigdog at columbus.rr.com> wrote:
>
> > Tim,
> >    Some 12 volt conversions require alternator speeds higher than
> normally
> > seen in the older tractor engines to get the alternator charging unless
> > they
> > are manually excited..  The previous owner apparently set up the toggle
> > switch to temporarily apply voltage to the alternator to excite it so it
> > would start charging.  This is often done with a diode or small lamp bulb
> > which will allow the alternator to start charging but not bleed back
> > through
> > the component to drain the battery when not running.  I have also seen
> > this
> > done with a pushbutton to prevent leaving the switch in the on position.
> >    The switch actually has nothing to do with the magneto at all.  As
> long
> > as you don't forget to switch it off after exciting the alternator you
> > will
> > be OK.  If it were me I'd replace it with a diode to eliminate the need
> > for
> > the switch altogether or at the minimum I'd replace it with a small
> > momentary contact pushbutton.
> >
> > ----- Original Message -----
> > From: Tim Savelle
> > To: Farmall/IHC mailing list
> > Sent: Thursday, March 11, 2010 7:03 PM
> > Subject: [Farmall] Turning on the magneto switch on Farmall "H"
> >
> >
> > One more question (for today, that is)....
> >
> > Ref: the switch on the side of the amp meter box beneath the steering
> > wheel.  The guy I bought the tractor from told me to flip what he called
> > the
> > magneto toggle switch up and then immediately back down to start current
> > flowing to the battery for recharging when the tractor is running.  It
> has
> > a
> > 12 volt system.  Does this sound correct, that you would flip the switch
> > up
> > and then back down?  Just out of curiosity, why is it necessary to do
> > this?
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