has my horn had it?

[Peetee]

It doesn't work you see.
Wired in place there is 12V coming in at one connector and 12V coming out at the other. Disconnect it and run wires from it direct to the battery and it still doesn't sound.
Ideas?

[Alec]

Hello Peetee,

if you get 12 volts out then the internal circuit is sound. If you have the type that you can dismantle (i.e. the old bulbous shaped horn.), remove the back and firstly clean the internal contacts. If, after that, it still doesn't work, there is an adjusting screw so give that a fiddle.

Good luck.

Alec

[Peetee]

If you have the type that you can dismantle (i.e. the old bulbous shaped horn.)

Well it's definitely bulbous but appears to be held together by a ring of flat rivets

[Alec]

Hello Peetee,

is there not a single screw right in the centre of the dome? Undo that and the back can be removed. Unless, your horn is not what I'm thinking of?
Have a look at http://www.holden.co.uk/displayproducts ... =Horns+12v
scroll down four lines and look for windtone horns. That is what I'm thinking of.

Alec

[Peetee]

OK the cover is off (that was fun as i'd got several coats of gloss black over the screw ) and I can see a set of contact breakers. Should they be closed? If open, by how much?

[Orkney]

If you hang on till tomorrow night I'll get you some pics of teh new one on scabby -

BTW your nominated for the thread of the year title which should have been sent to Dear Derdrie

[Peetee]

BTW your nominated for the thread of the year title which should have been sent to Dear Derdrie

Thanks, my double-entendres titles are always deliberate.

As for the electric audible warning device, I removed the cover, cleaned the contacts and adjusted to give a small gap but it still doesn't sound.

[Orkney]

As for the electric audible warning device,

OOOPS - thought this was the wonky indicator thread

[Peetee]

Well despite looking through all the manuals I can find (including the BMC workshop one) I still can't find out if the internal contacts should be closed or slightly open. Perhaps someone in the know can help???

[MoggyTech]

IIRC the contacts inside are actually the vibrating contacts that make the horn sound. They are oscillated by a coil winding similar to a solenoid. Normal adjustment is made by wiring horn to a battery, and adjusting the centre screw for best tone.

[Alec]

Hello peetee,

it should be closed, but it must have been or you would not have had 12 volts out?

basically it is a solenoid, and when the power is applied pulls in, deflects the diaphragm and also breaks contact which lets the solenoid de-energise, and a spring closes it moving the diaphragm back to the start position. If the power is still on then the cycle repeats itself very quickly giving an audible note
Be sure the contacts are very clean and have sufficient spring pressure (adjusting screw)

Alec

Alec

[Peetee]

Cheers for that. I'm pleased to say that it works now - well, at least it did last thing yesterday as my sleepy eyes guided me to the battery of Albert in the cold dead of night .
As it was, that was the third attempt. Eventually, working on the assumption it had been been put together wrong (there was evidence it had been unscrewed before) I resorted to dissassembling the contact set so all the insulators and metal plates could be checked. It was trying to work out the correct order for reassembly that took forever .

[Peetee]

Oh dear. Although it worked when connected directly to the battery, when wired in to the car circuit it just blows the fuse. I would guess that the two contacts that feed to the solonoid need to be swapped because one links to the body of the horn and then to earth. Does that sound feasable or could I just swap the two wires on the car loom?