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MG MGA - generator

Hi all,
Last week I fired up my new rebuild engine for the first time(the car is a complete restoration).When the engine was running smooth I noticed that the ignition lamp kept burning.
To test the generator I disconnected the terminals D and F and shorted them with a piece of wire and connected a voltmeter.No voltage.
So I dismounted the generator to check the brushes and the springs.They seemed to be OK.
The fieldwindings are OK with 6,5 ohm.
So I assume that the problem is in the armature.

Is there someone who can give me any tips to check the armature so I can check if the windings are OK.
Or is there something else that I can do?

Thanks,
Herman
H. Jorens

Herman, have you 'flashed' the field winding? If it is a new or rebuilt generator it may need doing. Momentarily touch the live battery feed to the 'F' terminal on the generator and it is done.
Lindsay Sampford

Yes you need to pre magnetise the field to allow the dynamo to start exciting itself. :)

This is very easily done and is generally refered to as "Fkashing" which is described very well by Lindsay above.
Bob Turbo Midget England

Herman,

If your generator is out of the car you can test it by bridging both its terminals together, connect a length of wire to this bridge wire, and touch this wire to your battery and earth its body. If generator is OK it should turn like a motor. Don't forget if your car is pos+ earth touch wire to the negative pole of batt. Polarising the field windings is important if the unit has been out of use for a considerable amount of time. Check its windings with a multimeter to make sure that they are not earthing to the generator's body. Do this by touching one probe of the meter to the commutator copper segments and the other to body, there should be no resitance here.
Hope this helps.

Frank
F Camilleri

Hi, Thanks for the comments.
Yes I polarised the generator(neg earth).
But tomorrow I will try to let the generator work as a motor if nothing happens I have a problem.
Regards,
Herman
H. Jorens

This thread was discussed between 26/04/2011 and 28/04/2011

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