I cleaned the points in the control box over Christmas due to intermitent charging,since doing this when the points "click in" the horn goes off, any ideas ?.

OH, I knew it would come to this...

Hello Kerbut,

I have no idea what particular A7 you have, but.....

Ordinary configuration for horn is that one side of the horn itself is connected to "battery" and the other side is connected to earth via the horn button contacts.

If you horn was working OK prior to your scientific experiments with the cutout contacts then you either have a coincidental fault in the circuit above described or else you have exposed a new field of electronic demonry.

May I suggest that you trace out the horn wiring and ensure firstly that it is wired as described above, then to ensure that there is no rogue earth on the "Horn Button side" of things.

Maybe (and I am thinking into the keyboard) the simplest test would be to initially remove the wire from the horn itself, which goes to the horn button switch, and see what then occurs. (It is possible to have an earth fault inside the horn.)

kindest regards

Barry R.

I have found the problem which I think was shear Coincidents ,Th horn wire at the bottom of the stator tube had the insulation broken.