[Farmall] More M electrical problems

DBigdog DBigdog at columbus.rr.com
Mon Oct 30 17:29:11 PST 2006


Dean,
    The only way for the screw to glow red is for it to be a current path to 
ground.  Though technically the entire frame is ground, due to paint, rust 
etc. where brackets, and braces attach there is resistance in the path and 
that causes heat.  You have a current path to ground at that location.  Even 
though the switch contacts are working, there is a short or low resistance 
path to ground on the low side of the switch or very close to it.


----- Original Message ----- 
From: Dean Vinson
To: 'Farmall/IHC mailing list'
Sent: Monday, October 30, 2006 7:49 AM
Subject: [Farmall] More M electrical problems


The starter motor on my 50 M seems to have quit, and there's something going
on around the starter switch that I don't understand.

Wouldn't start yesterday afternoon.  The starter gave a little click, and I
noticed a brief little puff of smoke from down near the starter switch, but
nothing after that.  I made sure the battery was charged up and tried again,
and there's definitely some current flowing around that switch somehow.
It's mounted to a piece of metal down below the gas tank, and one of the
little machine screws that holds it on there would glow red-hot if I held
the switch down for a few seconds.  After that one initial click, nothing
more from the starter.

It was getting dark so I took the battery out and the starter off and
brought them both inside.  Hooked the starter up directly to the battery,
and still nothing happened--no movement, but also no short, no current draw.
So I'll stop by a local electric shop and have the fellow there take a look.

But meanwhile, what would cause that little screw by the starter switch to
get red hot?   It only gets hot when I close the switch, so the switch
itself seems to be functioning okay.   But with the switch closed, the whole
frame of the tractor should be part of the circuit:  battery to switch to
starter motor, then back to the battery through ground.  The screw is
obviously grounded--so why does it get hotter than some other random screw
elsewhere on the tractor?

Not to mention why is there even any current flow to begin with, if the
starter motor isn't pulling it?

Dean Vinson
Dayton, Ohio
www.vinsonfarm.net

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