Trumpet horn

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PanJud
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Trumpet horn

#1

Post by PanJud » Sat May 09, 2015 6:53 pm

Now that my engine is rebuilt.....lesser things to worry over. My '62 has a 20 year old repop trumpet horn, and what they refer to as the "power pack" (It's a big oscillating coil, as I can tell) is shorted out...like 1 ohm. It isn't shorted to the case, and I don't know what ohm value a 12 volt is supposed to have, and even tho it's a repop, you can't even buy THEM anymore. (Currently bidding on one at Ebay) Anyone have experience rewinding these things?



dontsink
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Re: Trumpet horn

#2

Post by dontsink » Sun May 10, 2015 9:40 am

Hi, maybe this fits
http://www.vtwinmfg.com/webapp/wcs/stor ... 394_142396" onclick="window.open(this.href);return false;
http://www.vtwinmfg.com/webapp/wcs/stor ... 394_142395" onclick="window.open(this.href);return false;

PanJud
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Re: Trumpet horn

#3

Post by PanJud » Sun May 10, 2015 5:55 pm

dontsink wrote:Hi, maybe this fits
http://www.vtwinmfg.com/webapp/wcs/stor ... 394_142396" onclick="window.open(this.href);return false;
http://www.vtwinmfg.com/webapp/wcs/stor ... 394_142395" onclick="window.open(this.href);return false;
That's the first place I went....back-ordered indefinitely. Pretty much every site that SELLS them, gets them from Teds

john HD
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Re: Trumpet horn

#4

Post by john HD » Sun May 10, 2015 6:18 pm

Try adjusting it by the book before you give up on it.

you might be surprised!

john

PanJud
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Re: Trumpet horn

#5

Post by PanJud » Mon May 11, 2015 12:36 am

john HD wrote:Try adjusting it by the book before you give up on it.

you might be surprised!

john
Would that it were that simple....it's just like the old style piezo fire alarm horns....(which ALSO don't work when the windings are shorted). Drilled out the rivets...such as I can see of the winding part, it looks ok...shorts out the battery when you put volts to it tho. I might try rewinding it if I knew what the wire resistance was supposed to be (AND, if I had a bunch of that insulated wire;)

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Re: Trumpet horn

#6

Post by Scrap » Mon May 11, 2015 1:08 am

Maybe? http://www.carhornrestoration.com/faq.html" onclick="window.open(this.href);return false;

Perry Ruiter
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Re: Trumpet horn

#7

Post by Perry Ruiter » Thu May 14, 2015 5:07 pm

PanJud wrote:Now that my engine is rebuilt.....lesser things to worry over. My '62 has a 20 year old repop trumpet horn, and what they refer to as the "power pack" (It's a big oscillating coil, as I can tell) is shorted out...like 1 ohm. It isn't shorted to the case, and I don't know what ohm value a 12 volt is supposed to have, and even tho it's a repop, you can't even buy THEM anymore. (Currently bidding on one at Ebay) Anyone have experience rewinding these things?
You say it isn't shorted to the case, so you must be getting your 1 ohm reading by measuring across the two terminals. If that is the case then 1 ohm sounds perfectly normal. Think about what you're measuring when you measure resistance across the two terminals. There are a set of points and a coil of copper wire. As an aside, dirty points are the number one reason for horns to stop working. Let's assume your points are perfectly clean and insert no resistance. How long is the coil if unwound? I'm just pulling (reasonable) numbers out of the air, but lets say each wrap of the coil takes 6 inches of wire and there are 60 wraps, so you have 30 feet of wire. According to this copper wire resistance calculator 30 feet of #25 wire has a resistance of 1 ohm. I don't know that the horn uses #25 wire, but there are probably a dozen combinations that would be reasonable for this application and get you to an ohm (100 feet of 20 gauge for instance).

With the horn installed on the bike when did you experience the short? As soon as you hooked up the battery or only when you pushed the horn button? If the horn was fine until you pushed the horn button, and then the fuse blew the horn is not shorted out. Depressing the horn button creates a path to ground in that circuit. If the horn itself was shorted you'd blow the fuse as soon as you added power to the circuit since there would be a path to ground through the horn body.

PanJud wrote:
john HD wrote:Try adjusting it by the book before you give up on it.

you might be surprised!

john
Would that it were that simple....it's just like the old style piezo fire alarm horns....(which ALSO don't work when the windings are shorted). Drilled out the rivets...such as I can see of the winding part, it looks ok...shorts out the battery when you put volts to it tho. I might try rewinding it if I knew what the wire resistance was supposed to be (AND, if I had a bunch of that insulated wire;)
Of course it's too late now that you've drilled out the rivets, but John is bang on here. I've never seen this on OEM power packs but in my experience some repro power packs ground out when power is added if they are out of adjustment. I'm guessing the lower half of the points stack must touch the horn body when the coil is energized and the plunger is pulled in. Thinking about this now that I'm typing this up, swapping wires on the terminals may "fix" it, as then the ground side would be touching the body rather than the hot side, but I have a jumper wire that I inserted an old Shovelhead circuit breaker in that I use when adjusting power packs. If the horn grounds out it clicks off and I tweak the adjustment slightly, the circuit breaker resets itself and we try again ... Perry

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Re: Trumpet horn

#8

Post by Robert Luland » Sat May 16, 2015 11:04 am

This may help ya. When I rebuilt my JD horn, this were I got the wire. Two days of searching the internet because I didn't know what they called the stuff. Bob
http://www.planetengineers.com/product.asp?pid=1191" onclick="window.open(this.href);return false;

PanJud
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Re: Trumpet horn

#9

Post by PanJud » Sat May 16, 2015 4:32 pm

Thanks for the responses...I suppose it wouldn't be a big deal to replace the rivets and test it some more....I hadn't considered 1 ohm might possibly be normal. (I've since heard, which makes sense, that what kills these things is riding in the rain, and afore-mentioned rain being pushed right into the coil area) I've not taken it apart any further, might fiddle with it more. At any rate, it's just a Taiwan repop, and they tell me the things WILL be built again, just waiting on the pipeline

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Re: Trumpet horn

#10

Post by john HD » Sat May 16, 2015 4:49 pm

Just put some screws and nuts on it and fiddle away!

john

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