Altette Horn 6v - arcing on frame when bolting to bike?

[Julian Murphy]

You say 'brand new'.

But, from where?

I would be returning it as faulty, with a suspected internal short.

[JoeRoyle251]

OK,that makes sense - Thanks Julian I will definitely head all the advice

[JoeRoyle251]

“Classic Bike shop” have agreed to send me an another new 6v horn and let me diagnose and prove its the horn or not - maybe i got a lemon, at least ill know for certain wether its harness or Horn, as advised. (I was reluctant to open the horn because of warranty).
I’m Keeping you posted in case others come across something similar - Thanks all - Warnings and advice headed - and Much Appreciated.
Joe

[simon.holyfield]

Thanks all - advice noted - but the horn is brand new and not a refurbished horn, do you think that still could be it or should I pull the harness out?

I thought that horn looked a bit odd - I would be suspicious that the connections are not as Lucas intended. Both terminals should be isolated from the body, as has been said. This is a genuine Lucas one:

[Julian Murphy]

Simple test before fitting a replacment horn.

With all the wiring and batttery in place, with only the horn dis-connected.

Put a multimeter across the red and black wires. You should see 0 Volts.

Put a multimeter across the red and black wires. Press the horn button. You should see 6 Volts. (or 12V if yo have a 12V battery - obviously).

If you dont have a voltmeter, simply connect a bulb instead. The bulb should light when the horn is pressed.

Just looking at the photo of the back of the horn, it doesnt look very 'brand new'.

The terminal screw of the red wire looks odd. Why has it got a large head on it?

I cant make out the black terminal.

My terminal screws are headless and with a point to make the contact, and therfore do not protrude past the top of the terminal itself.

There looks to be a black 'dot' on the red wire. Is this where it is shorting?

[JoeRoyle251]

Apologies Julian, the photos are of the old one i took off originally Which didn’t work, I bit the bullet and bought a “6v Classic Altette Horn OEM: HF1234” from https://www.classicbikeshop.co.uk/ - so i fitted the new one which started this thread and they are sending me a new horn to test it and prove either harness or horn is causing this?
Your multi tests i did and through the wire i had 6 v when button pressed - electrically it just does not make sense - so ill wait for the new one and update when possible.
The original one i would try and rebuild, but am currently suffering a disability that’s affecting my hands - so wish to send out for refurb eventually - Taff the Horn, sadly now out the picture - so not sure where to get it refurbed, any ideas?
Thanks Joe

[Chris Sealy]

Hi Joe. Your "original" horn is almost certainly a Clear Hooters, see picture of a Clear Hooters horn. Lucas, Wipac and Clear Hooters all had two terminals; neither of them connected to the body of the horn. Your "new horn definitely has an internal short circuit between one of the terminals and the body.

[Mick D]

Hi

I am not overly conversant with all the 'Altette' models but could you have one that was intended for operation via a relay, (ie. sounds when power supplied)? I bought an HF 1244 destined for use on a car, but visually identical to a bike version, that was configured this way, (I knew, and was prepared to include a relay in the circuit). Just a thought.

Regards Mick

[JoeRoyle251]

Thanks guys, next week I’ll try the “new, new” horn and see if i get the same thing.
Mick, that’s an idea I’ll look into as well.
Thanks all - ill keep you posted Joe

[JoeRoyle251]

Hi All,

Finally solved the issue - It is as Chris Sealy said - The Brand new Lucas Altette Horn had an in Internal short - as you can see by the photo, i had 6v on the horn mount, when not attached to bike but wired in, it worked great, on the bike frame it didn’t, as per conversations previously.
Classic bike shop (thanks you guys) sent me a new 6v same part no and it worked a treat.
Just wanted to close the loop on this hoping it well help someone down the line - But mainly a big thank you to you all for the help, support and advice, it is really appreciated.

I do now have a redundant broken original horn, which has been bodged by previous owners internally, reluctant to take on replacing the coil yet don’t want to discard - anyone got any ideas of where i could get it refurbed or even donate it?

Thanks again

Joe