06-11-2021, 01:32 AM
I lost a post here unfortunately but I have just been through all this with a couple of Riley Rotax dynamos. The first, a 4 field 3 brush AT145 would motor slowly but I was never able to get more than 140mV output from it.
One good test is to disconnect the field and power that directly from another source then spin the dynamo to see what you get. I never got anything out of it. I think the issue is the field coils, which were oil soaked are internally shorting and had only half the resistance they should have (3 ohms instead of 6). When connected up as a motor though it would spin which does seem surprising.
I have now stripped and am rebuilding a second later 2 brush AT166 and this one does work. The field coils on that measure 6 ohms and are in much better shape. With the field connected to the output directly I can easily generate 14 or more volts with a drill driving the dynamo even at fairly low speeds.
I don't think the motoring test is a very conclusive one, at least not on the two dynamos I have here.
I found this very helpful for the Riley 4 pole dynamos. Not sure how applicable it will be to the A7 ones though: https://www.rileyregister.co.uk/wp-conte...e-2010.pdf
As I have nothing to lose I am tempted to rewind by hand the field coils on the broken one I have. Someone described doing it for a different dynamo here: https://www.a7a10.net/forum/index.php?topic=13999.0
Simon
One good test is to disconnect the field and power that directly from another source then spin the dynamo to see what you get. I never got anything out of it. I think the issue is the field coils, which were oil soaked are internally shorting and had only half the resistance they should have (3 ohms instead of 6). When connected up as a motor though it would spin which does seem surprising.
I have now stripped and am rebuilding a second later 2 brush AT166 and this one does work. The field coils on that measure 6 ohms and are in much better shape. With the field connected to the output directly I can easily generate 14 or more volts with a drill driving the dynamo even at fairly low speeds.
I don't think the motoring test is a very conclusive one, at least not on the two dynamos I have here.
I found this very helpful for the Riley 4 pole dynamos. Not sure how applicable it will be to the A7 ones though: https://www.rileyregister.co.uk/wp-conte...e-2010.pdf
As I have nothing to lose I am tempted to rewind by hand the field coils on the broken one I have. Someone described doing it for a different dynamo here: https://www.a7a10.net/forum/index.php?topic=13999.0
Simon