horn problem

roadster

roadster

Senior Member
I bought a Model A Horn at swap meet owner said it did work
but when i put 6v to it nothing happens. One time the armature did move slightly. What should I check?
 
armature turns free by hand. tried adjustment screw, wiring looks ok
here is picture
 

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Could be someone converted it to 12 volts.I had that happen to me.Of course if thats the problem there are a few people looking for 12 volt horns RAY
 
Thanks
hooked my battery charger and it did work some on 12v seems to
spin very fast ,when i adj. it works a little ,if adj more it stops.
when on 6v nothing
 
looks like I must have a 12v horn
it works some if I uplug the charger and replug it.
everything I have in Model A is 6v
 
Horns are not grounded. The current flows from the live wire off the cutout to the horn and then from the other horn terminal to the horn button. To check the horn off the car, attach one wire from positive battery to one horn terminal, and the other wire to battery negative and the other horn terminal. It does not matter which wire goes to negative or positive, the horn will operate in either direction.
 
i hooked it up to my battery charger positive to one terminal and neg. to other
it spins and by upluging and pluging acts like horn button.
 
To me the commutator looks like crap, looks cobbled together. The right brush is also barely in contact with the commutator. I would look for a new armature and get the bushes to contact fully.
 
I agree with Steve about the armature, but before you look for another one, try sanding this one a bit and make sure it undercut at least a few thousandths. It looks like someone used JB-Weld to glue the commutator segments in place, and some of the glue spilled over onto the top side of the segments. Sand it off, so you have a good clean smooth contact area. Also make sure each brush holder is isolated from the motor frame. Each of the 2 brush holder mounting screws has insulating washers on both sides of the motor frame, and if you need to insulate the shaft of the screw, you can use a short piece of heat shrink tubing.
Check the armature for shorts to ground. I'm guessing there's a reason someone painted the wires on it, and maybe it's shorted. The field windings look good, but check them also for shorts to ground.
Test the horn on a good 6 volt car battery, rather than the battery charger, and let us know what you find. When the horn is adjusted correctly, the armature ratchet wheel will barely touch the horn diaphram.
 
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