Forum

[Norm]

Anybody know what voltage reading I should get across the D and F terminals of a generator and which way the meter leads should be

[Dennis C]

Hi norm I guess you are talking Dynamo here, you cannot get any useful voltage reading across the D & F terminals as they are entirely different circuits, what is the problem you have?.

[Les H]

Hi Norm...thanks for the concern on my recent seize up by the way......As Dennis says they are separate ends of the Field and Armature coils. The magnetic remnance of the field coils and its core produce a small current in the armature. The armature current (A)is fed via the external terminals and through the voltage reg back into the field windings (F) and boost the field magnetism to produce the correct voltage. Anyway, you probably know this but there are two tests: 1) to measure the resistance of the two coils noting that the armature coil is a collection of coils that are connected to the commutator. 2) Best way to test a dynamo is to short together the A & F terminal and measure the voltage at various revs back down to the dynamo chassis..... http://classicrider.dk/dokuments/Lucas/ ... E3N[2].pdf

[Les H]

Additional: the armature coils are in contact with the carbon brushes....one brush connected down to earth the other brush output goes to the A terminal.

[Les H]

Hi Norm...this pdf is probably better for you: http://www.fhf-oldtimer.ch/downloads/lucasgenerator.pdf
....to check current it is better to wire the dynamo up to the regulator....and use the Lucas figures. The simple test of shorting the A & F together and measuring the voltage from this cross connection down to the dynamo chassis should give around 10V at around 2-3000rpm

[Norm]

Thanks Les,
I knew there was a way of testing across the D and F terminals but I couldn't remember.
Dennis,
No problem with it I am putting it on ebay and wanted to know if it was still working. It is off the 54 Meteor that I now have an alternator fitted to.