Morris Minor Owners Club

I started my pick up the other day and the red light kept on. So i changed the dynamo, which sorted it. However I should like to know why the original one failed The brushed although worn looked serviceable but I seem to recall there is such a thing as the armature possibly being open circuit or problems with the copper segments. Can one of you electrical wizards explain more and suggest any possible checks that can be done off the vehicle, thanks.

Most likely sticking brushes - could have been stuck just clear of the commutator. I would remove and clean the brushes - fit new if badly worn, otherwise refit - checking they are sliding freely. Then join the two terminals with a length of wire - earth the casing to the car earth terminal of the battery and touch the wire to the other terminal. The dynamo should run as a motor.

Ok thanks, will try that.