Horns not working....

[D3B]

I am sure power is getting to them.

i ahve a master switch in the cabin, connected to helm rocker switch.

Opearting the rocker switch gives a shallow popping type noise, which makes me believe they are getting power.

taken the covers off and there is corrosion around the connections....cleaned them off but still not working...

 

[VicS]

Check that you really do have power getting to them with a voltmeter or a bulb on a couple of leads.

take em off and test them directly on a battery.

 

[smileygirl]

often there are contacts inside the horn itself that act as an oscillator with the diaphgram. Try cleaning the contacts with an emery board.(this will only work a few times) Also horns take a lot of current so check out any dodgy connections or water ingress along the wires. Measure the voltage at he horn itself - make sure you have @ 13.6V or similar.

 

[nimbusgb]

Those horns should have been mounted the other way up, with the open ends facing downwards or at least horizontal. The way they are mounted they will fill with water when it rains and rot the insides which is what might have happened in your case.

There are 3 red 'sealed' screws on the casings of the horns, one or more of of them is the tone adjustment screw or screws. Adjusting the right one will get the diaphram to vibrate again, playing with it and repeatedly blowing the horn may recover them slowly. Spraying liberal amounts of WD40 or similar up the horn throat may help, rapping the body sharply may too.

The horn works like a speaker. An electromagnetic coil pulls in a diaphragm, the power to the coil passes through a set of contacts, one of which is actually mounted on the diaphragm. As the diaphragm moves away from the resting point the contact is broken and the diaphragm stops and returns to the neutral point, when it does the contact is made and the cycle begins again. The general tone of the horn is fixed around a centre frequency that depends on the dimensions of the diaphragm, the contacts spring loading etc.

In your case it is highly probable that the contacts have corroded together, probably aided by the ingress and pooling of water given the horns orientation.

I have recovered a few horns by doing the above but they seldom last very long afterwards and frequently start to issue squeaks and peeps instead of usable hoots, even with readjusting. A strip down and rebuild may be possible but given today's manufacturing techniques highly unlikely.

New horns mounted the other way up may be inevitable.

( Blimey all that for a knackered horn /forums/images/graemlins/smile.gif )

 

[pvb]

[ QUOTE ]
Those horns should have been mounted the other way up, with the open ends facing downwards or at least horizontal. The way they are mounted they will fill with water when it rains and rot the insides which is what might have happened in your case.

[/ QUOTE ]Now I may be wrong, but D3B has a Sealine S29, which has the horns and steaming light on an arch. If you look at the steaming light in his pic, you'll see it's pointing skywards, which would seem to indicate that the pic needs rotating 90degrees clockwise. The horns would then be seen to be horizontal, as in this Sealine pic...

 

[D3B]

Nice 12 volts.....

they are wet inside....so i guess knackered....

 

[D3B]

Er scuse me guys....when you have quite finished....Picture is taken above them....they face horizontally as in the pic of the S29........but backwards....

 

[steve28]

i can see what you mean, the picture at the top of the horns has been taken at an odd angle giving the impression the horns are upside down !