VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Fixing a horn

Has anyone taken a horn apart to try and fix it? I bought a 1939 engine for parts and it has the correct horn on it. I took it off and connected it to a battery with jumpers and got nothing. I'd like to sand blast it, paint it and put it on my 38 but I would like it to work. I'd rather not ruin it trying to take it apart if there is no fix to it.

How did you connect it?

There are 2 insulated posts on the side. I put jumpers on those and then to the battery. Should I have only used one of the posts and then grounded the body of the horn?

Not sure of your exact horn but I believe you would use the terminals. One would be hot and the other the ground. Did you try both ways of wiring it? Hot to one and ground to the other then switch the wires if it doesn't work? If it's dead both ways you might try pulling the cover and see if a wire has broken.

There are lots of posts on this forum about removing the horn cover and cleaning the contacts. A horn is simply a make/break relay with the moving arm attached to a diaphragm to make noise. There is also an adjustment to set the point clearance so the relay operates properly.

As mentioned, it's a pretty simple device and lot's of posts on it. I think the biggest thing to watch out for when taking apart is making sure the insulators stay intact around the two terminal posts isolating them from the body of the horn. There will be gaskets on each side of the diaphragm easy enough to make out of some thin gasket material if yours get torn.
My Klaxon horn for my 28 didn't work until I cleaned up the brushes to the motor and lubed up the little bearings on each end with some 3-1 oil. Worked great after.
I don't think there is a positive and negative specification to them but would have to double check that. Maybe there is a + & - stamped on the housing.

There are 2 main types of horn design, the common type is a magnet pulls a metal dish out of shape but this opens a set of points which turns off the power so everything goes back to normal position allowing the points to close and repeat the process, this type is the most common even in modern cars. The not so common type has a small electric motor and diaphram but it is a lot of years since I had 1 of these apart I am not sure of how they work now, a lot of sirens had a fan the forced the air through a special mesh.
Tony

Thanks for the information folks. I think rather than risk messing it up drilling the rivets out I'll just relocate the working horn and mount this one for show, at least for now.

Can you post photos of the horn? I don't think you have to drill rivets to take the stock horn apart.

As tiny suggests I dont think they are riveted together, all that I have seen are held together with short screws but they may well be well rusted in place though.
Tony

Thanks folks, after looking at it for awhile, I see that the back cover is just held on with one screw (which somehow was removed without too much effort). Lots of rust in there but everything seems intact. Not sure what is supposed to move or how far to make it work. I did clean the points and tried to get at most of the rust without damaging any insulation. I could take it back out to a battery and try it again now with the points cleaned up. Maybe tomorrow.