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trojanhorsepower |
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#1
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Senior Member ![]() ![]() ![]() Group: Members Posts: 941 Joined: 21-September 03 From: Marion, NC Member No.: 1,179 Region Association: None ![]() |
None of the horns I have worked. I looked online but couldn't find anything about how they work (no doubt due to my own poor Googling) so I decided to figure it out myself.
In principal the horn works by by using an electromagnet to pull in a diaphragm. When the diaphragm is deformed the steel plates on the back open the points. Once the points are open the diaphragm relaxes, the points reconnect and the magnet turns on again. Here is the process I went through to restore mine. |
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trojanhorsepower |
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#2
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Senior Member ![]() ![]() ![]() Group: Members Posts: 941 Joined: 21-September 03 From: Marion, NC Member No.: 1,179 Region Association: None ![]() |
The horn is often riveted together, with aluminum rivets.
![]() These rivets are easily chiseled off or drilled out. Personally I think a small hammer and cold chisel worked best. I gently hold the horn in the vice and carefully chisel off the rivet head that is against the vice jaw. Then turn the horn to the next rivet. The back of the horn ![]() |
trojanhorsepower |
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#3
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Senior Member ![]() ![]() ![]() Group: Members Posts: 941 Joined: 21-September 03 From: Marion, NC Member No.: 1,179 Region Association: None ![]() |
Once the horn is apart the pieces look like this.
Attached image(s) ![]() ![]() |
trojanhorsepower |
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#4
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Senior Member ![]() ![]() ![]() Group: Members Posts: 941 Joined: 21-September 03 From: Marion, NC Member No.: 1,179 Region Association: None ![]() |
Here is a close up of the dirty point.
![]() and the points separated for cleaning. ![]() |
trojanhorsepower |
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#5
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Senior Member ![]() ![]() ![]() Group: Members Posts: 941 Joined: 21-September 03 From: Marion, NC Member No.: 1,179 Region Association: None ![]() |
I cleaned up and treated the parts with Ospho.
Here is the front of the diaphragm. Attached image(s) ![]() |
trojanhorsepower |
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#6
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Senior Member ![]() ![]() ![]() Group: Members Posts: 941 Joined: 21-September 03 From: Marion, NC Member No.: 1,179 Region Association: None ![]() |
The parts cleaned up and painted
![]() And reassembled ![]() |
dtmehall |
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#7
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Member ![]() ![]() Group: Members Posts: 154 Joined: 21-December 23 From: Farmington Hills, Michigan Member No.: 27,808 Region Association: Upper MidWest ![]() |
Cool! Nice Work. thanks for the pictures
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914werke |
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#8
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"I got blisters on me fingers" ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 11,389 Joined: 22-March 03 From: USofA Member No.: 453 Region Association: Pacific Northwest ![]() ![]() |
Nice job Ive been rebuilding "dead" horns for years. In almost all cases it was necessary to remove the potting & reset tone for a consistent noise.
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