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

[DBigdog]

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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