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peter scott
Joined: 18 Dec 2007
Posts: 7118
Location: Edinburgh
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 Posted: Thu Sep 24, 2020 9:08 pm Post subject: |
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The wire top right looks suspicious to me. (D to C in Peter L's photo below)
Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon
Last edited by peter scott on Thu Sep 24, 2020 9:30 pm; edited 2 times in total |
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Peter_L
Joined: 10 Apr 2008
Posts: 2680
Location: New Brunswick. Canada.
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| Posted: Thu Sep 24, 2020 9:11 pm Post subject: |
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May help telling and explaining what is or should be happening between various points. |
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MVPeters
Joined: 28 Aug 2008
Posts: 822
Location: Northern MA, USA
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| Posted: Thu Sep 24, 2020 9:12 pm Post subject: |
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Ray
That horn really doesn't look in bad condition. If the points are clean I think I'd re-assemble it, connect 12V to it & play with the adjustment screw. You should get some sort of reaction.
Note 1: I have had similar volt-meters - I am now on my 3rd.
Note 2: I certainly wouldn't pay 200 pounds, euros or dollars for that pip-squeak! I'm sure you can find one at an auto-jumble.
Note 3: My 1934 J2 had a pair of Lucas Windtones out front.
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S' |
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Ray White
Joined: 02 Dec 2014
Posts: 6304
Location: Derby
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| Posted: Thu Sep 24, 2020 9:34 pm Post subject: |
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| peter scott wrote: | The wire top right looks suspicious to me.
Peter |
Peter believe me it is just the photo. The wire is kind of flat and twisted over. Looks like it has always been like that.
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peter scott
Joined: 18 Dec 2007
Posts: 7118
Location: Edinburgh
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| Posted: Thu Sep 24, 2020 9:51 pm Post subject: |
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OK Ray, I believe you. I'm still concerned about the conductivity of the diaphragm to the case of the horn.
Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Ray White
Joined: 02 Dec 2014
Posts: 6304
Location: Derby
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| Posted: Thu Sep 24, 2020 9:54 pm Post subject: |
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| MVPeters wrote: |
...."that pip-squeak!" |
Careful what you say about my little hooter. I might get a complex or something.  |
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Ray White
Joined: 02 Dec 2014
Posts: 6304
Location: Derby
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| Posted: Thu Sep 24, 2020 10:08 pm Post subject: |
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| peter scott wrote: | OK Ray, I believe you. I'm still concerned about the conductivity of the diaphragm to the case of the horn.
Peter |
Peter. I don't like the look of that diaphragm either. However, I feel the need to establish that the coil is O.K. before going further with the restoration. I don't think I need the diaphragm in situ to do that do I? . |
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peter scott
Joined: 18 Dec 2007
Posts: 7118
Location: Edinburgh
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| Posted: Thu Sep 24, 2020 10:23 pm Post subject: |
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I don't disagree but the diaphragm looks obviously wrong and the lack of a multimeter just makes testing the innards rather difficult and it all looks quite good anyway. You might not need to do anything with the innards. Why not eliminate the obvious and easy first?
Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Ray White
Joined: 02 Dec 2014
Posts: 6304
Location: Derby
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| Posted: Thu Sep 24, 2020 10:30 pm Post subject: |
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| Peter_L wrote: |
May help telling and explaining what is or should be happening between various points. |
I am no good with electrics which is why I am asking stupid questions. Anyway I am at a loose end this evening so here goes.
Think of A to B as being either end of a coil (the shiny disc in the middle). B and C have insulated terminal blocks (mounted on the other side of the casing) to which wires go to the horn button and ground. D is a screw adjuster (again operated from the other side) that raises the level of the lower half of the points (G) to compensate for wear. E is the top part of the points assembly and is riveted to - but insulated from - G. These points should be closed when at rest and the whole assembly is secured to the magnet J. H is the iron core that is threaded through the body of the horn and adjusts the diaphragm/armature which in turn is secured by six studs to the body at K .
No doubt I will be corrected forthwith. |
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Ray White
Joined: 02 Dec 2014
Posts: 6304
Location: Derby
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| Posted: Thu Sep 24, 2020 10:47 pm Post subject: |
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| peter scott wrote: | I don't disagree but the diaphragm looks obviously wrong and the lack of a multimeter just makes testing the innards rather difficult and it all looks quite good anyway. You might not need to do anything with the innards. Why not eliminate the obvious and easy first?
Peter |
Actually, I had planned to replace the diaphragm with a better one. The original has rusted quite badly; so much so, I have been unable to unscrew the nut.
The rippled steel tone disc was also rusty but that is a heavy item that I can clean up. The studs are rusted in as well so I would like to replace them with new stainless steel ones but the acorn nuts are in good condition and the chrome bezel is now with the platers.
I will replace the waxed gaskets while I am about it.
If I can be certain that the coil is in good condition I feel it will give me a solid foundation on which to build.
As far as I can tell there is only one specialist who rebuilds old horns. I have yet to make contact with him.
http://taffthehorns.com |
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peter scott
Joined: 18 Dec 2007
Posts: 7118
Location: Edinburgh
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| Posted: Thu Sep 24, 2020 10:47 pm Post subject: |
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You are probably right Peter. I was thinking that the diaphragm was part of the electrical circuit but certainly that doesn't explain the insulator G.
Peter 
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Peter_L
Joined: 10 Apr 2008
Posts: 2680
Location: New Brunswick. Canada.
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| Posted: Thu Sep 24, 2020 11:13 pm Post subject: |
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Here are two items that should be in the toolbox if you are working on vehicle electrics. The jumper cable, (white) I have several at different lengths and a couple with a large clip at one end that will grab a chassis bolt or lump of metal. Electric meters are an excellent addition but back in the day (1950's) when I first started my electrical career, they were for the very rich or "borrowed" from work. Ahh,, the first AVO's, love at first use.
Ray... I would guess that you have likely spent more time on this car horn that it would take to make up some test equipment. Trying to press, simultaneously "pointy probes" onto two connections, while looking at a digital readout on a meter that may even have an issue of its own is a frustrating, time wasting exercise.
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Ray White
Joined: 02 Dec 2014
Posts: 6304
Location: Derby
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| Posted: Fri Sep 25, 2020 1:57 am Post subject: |
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| Peter_L wrote: |
Ray... I would guess that you have likely spent more time on this car horn that it would take to make up some test equipment. Trying to press, simultaneously "pointy probes" onto two connections, while looking at a digital readout on a meter that may even have an issue of its own is a frustrating, time wasting exercise.
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I have these. They have very sharp ends for poking through to the wire. The light comes on if it is live.
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peter scott
Joined: 18 Dec 2007
Posts: 7118
Location: Edinburgh
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| Posted: Fri Sep 25, 2020 7:45 am Post subject: |
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If the light is a neon I don't think it will come on with 12 volts.
P.
_________________
http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Ray White
Joined: 02 Dec 2014
Posts: 6304
Location: Derby
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| Posted: Fri Sep 25, 2020 8:10 am Post subject: |
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| peter scott wrote: | If the light is a neon I don't think it will come on with 12 volts.
P. |
I am sorry but I don't follow ?
They work well on 12 volts.
I have had them many years. - they probably belonged to my Dad originally. |
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