Boxerworks.com

I just picked up a really nice looking chrome centred Bosch horn that looks like it's never been used:
Problem is it doesn't work. No spark when I connect a battery and no sound whatsoever. I thought these things were a simple coil and therefore pretty foolproof, but I was clearly wrong. There's no way of opening the thing up and I've already played about with the screw (turned it in and out) to no effect.

Anyone ever fixed one of these?

What does the other side look like? Horns should work one of a couple of ways...power in one terminal, out another terminal to ground; or power in to one terminal and the mounting point becomes the ground path back to the battery.

Kurt in S.A.

Here's the back view:
There was a blob of sealant over the screw head that I removed...

Give it a whack with a broomstick. Maybe the points are stuck.

Put a multimeter across the terminals on the Ohms range. Should show a low resistance. If not try winding the screw in and out to see if it makes any difference. If you don't get any chage afert winding the screw in and out (fully) six or seven ti8mes, it's bound for the bin.

Rob

Big thanks to George and Rob!

Ran a multimeter across it to start and it read 1.00 which was bad. Then I hit it hard (not a broomstick, but the back of a wire brush) and turned the screw in and out six times and now the multimeter reads 0.01 which is good! After a bit of adjustment with the screw the horn is now sounding fine and ready to go on my restored '74 bike.

Whether it was the "percussive maintenance" or the screw or both I'll never know, but I am indebted to you for your help.

"percussive maintenance"

DanielMc wrote:"percussive maintenance"

Yep, yer can't beat it!

ME 109 wrote:

DanielMc wrote:"percussive maintenance"

Yep, yer can't beat it!

Or yes, you can!

One of the many charms of wood is that it can be used to beat recalcitrant metal things into behaving properly.