Author Topic: Field coil wiring.  (Read 620 times)

Offline warmshed

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Field coil wiring.
« on: 29.07. 2012 09:07 »
Reflecting on the dynamo, Long time since I have needed to play with them. How can you determine which side of an unmarked field coil goes earth? Will "motoring" the dynamo give a clue in the direction it rotates? If so am I correct in thinking it would need to motor in the direction it will be driven if not then reverse the field leads?.

I see from the old Lucas service sheet that one lead of the field is normally sleeved and its difficult to see but it seems to go to the earth terminal, is this right?

Finally, what would happen if the field was reversed? would it still give correct output?
Many thanks. Dave

Offline duTch

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Re: Field coil wiring.
« Reply #1 on: 29.07. 2012 10:20 »
Hiya Warmshed, I too have been following the dynamo hum sagas running concurrently, and have been the last few days doing same.
  I had 2 armatures and respective fields checked out the other day, and double checked re; connections, as each one I had was wired opposite and both motored correctly(even though one had a stuffed armature the other a stuffed field), so it doesn't matter which way they're wired so long as  they motor in the direction of the arrow(in the direction of charging rotation,as you say).
 I specifically asked as I figured it would change the "magnetic polarity', but it apparently doesn't matter. Hook up the field and brushes, and if it motors the wrong way, just switch the brushes over and it should motor the correct way.
 Also keep in mind that As Trev(?) pointed out that just because they motor, doesn't necessarily mean they'll generate!!!
 I had a dud of each field/armatureand built a so far functional one from the refuse(all tested ok with the meter/other tests but the 'growler' said different) .
 And don't forget to polarize field connection that's not earthed, to -VE.
   someone let me know please if I got any wrong??
 Cheers duTch
    edited /added this bit...      (even though one had a stuffed armature the other a stuffed field)
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy