Fordson Technical tips


home page   Fordson Major Breaking Tractors  Fordson New Parts  Fordson Major used Spares   current projects    technical tips  Sliverline tools  Gallery        










Dynamo polarisation

If you are talking about a true DYNAMO with two tappings that being the D terminal which is the out put and an F terminal which is the Field windings then it is very simple, you do it by "FLASHING" the Field winding to the none earth terminal of the battery.
So first thing to do is Disconnect the battery fit the dynamo and ensure the casing is properly earthed to the chassis or frame of the vehicle.
Do not connect the terminals and ensure the Regulator is isolated from the vehicles wiring system.
Reconnect the battery to the circuit.
Now using a length of insulated wire with the ends bared, first attach one end to the None earthed Terminal of the battery and then "TOUCH" or FLASH the other bare end onto the F or FIELD winding on the dynamo you should see a small spark and the dynamo will "SHUNT" slightly. do this three or four times
Disconnect the wire and then the earth terminal of the battery. Connect the Dynamo to the regulator and ensure the regulator is properly connected. the Reinstate the battery connections: start and gently rev and ensure the charge warning light goes out or that the output from the regulator and the dynamo are within boundaries
SO for +ive earth setups you flash from the negative terminal to the field winding
for -ive earth set ups you flash from the positive terminal to the field winding.

PS on the back of the dynamo the larger terminal is the D or output. and the smaller is the F or Field winding