Repairing a shorted horn

[sebby110]

Howwdeee!
Ok, so here's my latest adventure.
Yesterday, on my commute to work, I noticed I had no functioning horns. (A mercedes cuts me off, I press the button and....nada, whew got out that mess with a bit of wrist twist !!)

Got everything working when I got home.
I have power, button works to ground, had to replace both horns with one spare I had on hand. Everything is hunky-dory !

Both horns show an open coil circuit. I wrapped on them and sprayed some Electra-cleaner to see if I might shake something back into place. But Na !!
I'm thinking of opening them up and tinkering in there to bridge the open circuit. I figure it must work similar to a house bell ? a coil around a diaphram-type devise. Don't know
Anyone try this ? Just curious of what to expect.
I could just buy a single horn and chuck these, but I love a new challenge. And it's nice to hold on to "functioning" original stuff anyway.

Appreciate any insight !!

[Steve]

New horns are $12 each at Auto Zone, get two of them ( one high, one low), have some sound while enjoying your exploration.

.

[sebby110]

Gotch ya
I'm figuring it shouldn't too complicated. The hardest part is probably opening the body without tearing it up.

[robertbarr]

Both horns measure as open, with an ohmmeter? I wonder how both would die of the same cause.

Since they're deceased anyhow, you can't really hurt them any further. If you find anything photo-worthy, post away...

[sebby110]

Yea Robert.
That was my initial thought (???). Both horns prove open on the meter. I get some ohms, but not "infinity". What are the odds of that happening to both at the same time ??? No way of really knowing if it did happen at the same time--it's not like I'm using them everyday.
I thought I might have a problem when I installed my spare (maybe it would short out too) but it works fine.

Thanks

[barnbiketom]

I'd check your charging voltage at like 3000 rpms. hopefully it is 14.5 or so. if higher ,

you would need to check that out. It might be burning things out man!!!!!!!

you said you have TWO horns and both were bad.?? what makes you think they both

went bad just now. I have worked on cars and such, and most people don't bring them in until ALL the headlites are burned out and they have no lites or horns or whatever at all lol.

maybe one went, you didn't notice it, then finally when the other went you did//??

at any rate, the horn works like this:
theres an electomagnetic coil with a contact. it is always "ON" or connected.

when power is applied, the coil and attached diaphram moves.and it also opens up the contact. It then all SLAMS back together.. and on and on and on and on going BEEP BEEP BEEP BEEP.
When you measure the resistance, I'd think it would be fairly low , in the 5-10 ohms range maybe.. as horns draw a few amps from what I remember.. lets say 3 amps. Then using ohms law E=I x R.. volts = amps times resistance. you know the voltage is around 14 volts. ok lets make the current like 3 amps if I remember correctly.
Resistance then would equal volts divided by amps, or 4.666 ohms. I think your horns are bad lolol.. they should have pretty low ohms at rest. the point contact is bad, or the coil is burned out.

[sebby110]

barnbiketom;

Thanks for the input.
My thoughts extacly on;
1- horns dysfunctional at separate times (I really don't use them all that often to be sure and say they fried at the same time)
2-I'm guessing either the coil or contacts have issues too.
3. I will check the voltage out at 3,000RPM. But all other electrics work fine (lights, signals, starter, cluster, etc). Didn't fry anything else.

Haven't seen V=IxR in along time. Took me back to HS days physics class.

When I put my meter on the working horn, it reads full resistance "infinity" across the contacts. And beeps away when connected !!

Thanks for the insight on what to expect once I open them up.
I'll be going to autozone. For $12 bucks, it's not gonna break the bank.
But I just gotta know wassup !!!

To be continued

[barnbiketom]

when you say infinity, that is an open circuit. i think your meter is bad or you are reading 0.00000 instead??? which is a total short???
if you are on the incorrect range, it may read .0000000. meaning in millions of ohms it can't distinguish a very low reading... place it on the lowers ohms range (0-200???)

[Matchless]

The horn has a break contact which is adjustable with a little screw and a locknut. Probably those contacts are dirty or not making properly.

Undo the locknut and slowly slacken off or tighten the screw until the horn makes some sort of noise then adjust carefully for a nice sound! I have resurrected many a dead horn in that way.

[sebby110]

Matchless;

I've worked the front adjustment screw on other horns and have brought them back to life too, so I know exactly what your saying.
I tried that with these but it didn't work. I'm gonna keep working it as you suggested and see how it goes.

Thanks