Lucas E3N does not charge after armature replacement

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Ed Field
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Lucas E3N does not charge after armature replacement

Post by Ed Field »

Hi All,

The dynamo of my '57 AJS 16MS is bothering me for a few weeks....since I bought the bike in december the dynamo does not charge. After checking all possible known matters I came to the conclusion the armature had to be the problem.

I ordered a new armature at the club, completed it with new brushes and rebuilt the dynamo, including new bearings.

But, the dynamo still does not charge, when I power it on 6 volts as a motor it works, and the speed doubles at 12 volt. When mounted on the bike at idle ( with the Field and Dynamo wire together) there is a charge of 0,12 Volt (and I have checked if my multimeter is correct at 20V and working properly ;) )

The field coil has a resistance of the correct 3,2 Ohm.

Somewhere along the line I made a mistake...who can help?

greetings from Holland,

Ed
Ed Field
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Joined: Fri Dec 30, 2022 7:38 pm
Location: Limburg, The Netherland

Re: Lucas E3N does not charge after armature replacement

Post by Ed Field »

Update on this problem, changed the position of the brushes and now the dynamo is charging, but unfortunately up to about 12 volts at the battery connections, also the ammeter will not give a reading....

Well, anyway the rebuilt of the dynamo worked out, but now trying to figure out if the regulator is defective, it's an original Lucas, but brand new...

Someone any ideas what I'mm doing wrong?

This was a sunday afternoon well spent with my AJS, it's a good companion in the garage.

Have a nice evening all,

Ed
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clive
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Re: Lucas E3N does not charge after armature replacement

Post by clive »

Dark science dynamos. My immediate thought was have you flashed it over to ensure it is running on the correct polarity? To do so take a wire from the live terminal on the battery not the earthed one. Remove the connection from the dynamo and brush the wire from the battery quickly against the field terminal. Do this a couple of times. It should give a small spark as you brush it.
clive
if it ain't broke don't fix
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clive
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Re: Lucas E3N does not charge after armature replacement

Post by clive »

With your update it sounds like the regulator is not working. If you changed the brushes this would have the same effect as flashing over.
clive
if it ain't broke don't fix
Groily
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Re: Lucas E3N does not charge after armature replacement

Post by Groily »

When you motor it Ed, does it turn the same way it will be driven on the machine?
If it doesn't, you'll see almost no output at any rpm.
There are 2 options to reverse the rotation - either swap the brush-tail connections over, or swap over the F and Earth wires from the field coil. Not both, or you end up where you started. Then motor it again to see if it goes the way it needs to.
If you motor it using the earth you want on the bike, then that will polarise it at the same time.


Oops - just seen you've swapped the brushes and it works (excellent!) so the above is irrelevant probably. So I've italicised the redundant bits.

But, no charge shown at ammeter but 12v at the battery . . .??? I'm assuming it's a 6v system . . . In which case, I would say the regulator isn't regulating.

What do you see if you put a meter on the dc volts scale between the A wire off the regulator and earth? It should show a rising voltage to about 1750 rpm engine, which then settles to a steady(ish) 7.2v roughly as the regulator starts to control and maintain the charge rate. If the voltage keeps on rising, then there is a problem with the regulator - or there is a path (short) between D and F somewhere else.

You say you have a new 'original' Lucas regulator. The new replica ones are not highly-regarded (to be polite), but assuming it is in good shape whatever it is, there are some fairly delicate tests and adjustments you could do to ensure the set-up is correct - see for example https://www.a7a10.net/BSA/lucasmain.htm where the Lucas data for MCR and RB types are detailed.

If it were me, which it isn't, I'd use an electronic regulator which can be concealed in the original cover, as I have found them far more reliable, especially https://dynamoregulators.com/dvr2.php

Aside: swapping brushes isn't the same thing at all as flashing the field Clive.
Swapping brushes or field coil wires changes rotation; flashing is for setting polarity. Both matter a lot, but the dyn will produce output of one or other polarity with F and D connected, but won't produce anything much if the rotation is wrong regardless of polarity.
Ed Field
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Location: Limburg, The Netherland

Re: Lucas E3N does not charge after armature replacement

Post by Ed Field »

Hi All,

Thank you or your reply's and possible solutions! If I wire it up the rotation is correct, it is anti-clockwise turning, just as it should be on the bike. For as far as the flashing, I did this alreadybefore mounting the rebuilt dynamo just to be sure.

It is ideed a 6 volt, positive earth system.

Groily, thank you for your special helpful input.I will conduct the test with the A-wire tomorrow, and get back to you then..

As I rebuilt the dynamo just the way it was with the brushes I suspect the original armature was not defective, but just a faulty installation...I'll have to check up on all the wiring I guess!

Have a nice evening,

Ed
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Les Howard
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Re: Lucas E3N does not charge after armature replacement

Post by Les Howard »

You say the dynamo works and charges at 12v but no charge shown on the ammeter. Are both the dynamo and regulator body earthed ...Just check the wiring its all very simple:
LUCAS WORKSHOP INSTRUCTION MCR2.pdf
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Groily
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Re: Lucas E3N does not charge after armature replacement

Post by Groily »

Ed Field wrote: Sun Jan 29, 2023 9:07 pm
As I rebuilt the dynamo just the way it was with the brushes I suspect the original armature was not defective, but just a faulty installation...I'll have to check up on all the wiring I guess!
Ref the wiring, worth checking that it's correct at the ammeter since that is showing nothing.
Could be that the A wire from the regulator, the link to the main switch and the onward feed to the battery are muddled, or could be the instrument isn't working properly. But if you are seeing that high voltage reading at the battery, current is obviously getting to it somehow and it should be via the ammeter unless it has been by-passed.
Any basic dynamo wiring diagram will show the required layout - there are a few reproduced on here, also lots in the manuals etc.
Good luck!
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clive
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Re: Lucas E3N does not charge after armature replacement

Post by clive »

Groily wrote: Sun Jan 29, 2023 5:54 pm Aside: swapping brushes isn't the same thing at all as flashing the field Clive.
Swapping brushes or field coil wires changes rotation; flashing is for setting polarity. Both matter a lot, but the dyn will produce output of one or other polarity with F and D connected, but won't produce anything much if the rotation is wrong regardless of polarity.
I bow to a wizard in the dark science. Somehow in the past I must have got away with getting dynamos working without actually knowing what I am doing! :rofl: However as I have one on the bench due to a burnt out armature at the moment I will take note of reversing the brushes as one possible fix if I cannot get joy from the new armature (when I can get the sprocket off!)
clive
if it ain't broke don't fix
Ed Field
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Re: Lucas E3N does not charge after armature replacement

Post by Ed Field »

Thanks all, you're a great support helping out!

I've been conducting some tests again. At about 2500 RPM the voltages at the regulator are; about 3 volts at the Field connection, about 10-11V at the Dynamo connection, and about the same 10 to 11 V at the Ampere-meter connection...so I think Groily is right, the regulator is not working properly.

For what I wrote about "the Thing" being a new Lucas regulator, it is indeed new, but I think it's a cheap Indian or Chinese knock-off looking about the same. The brand name Lucas is not even present. Although is appears to be regulating something it's impossible to see when it is regulating what. Only thing what is certain it cuts the supply off at idle.

I am a bit familiar with all those (clone and knock-off) electronics, as I have a few Royal Enfields as well, even a '54 with the nightmare Magdyno...

I'll order a new regulator first at the Dutch club an go on from there.

If anyone has better ideas or input, let me know!

Thanks for all your help, greetings from Holland,

Ed
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