Hi Guys
I have a friend with a 1952 A10 with a no charge issue. The generator is a Lucus E3L-L1-0 but i'm not sure the internal wiring is correct. The generator will motor with "D" and "F" bridged but i are getting no voltage when running with "D" and "F" Bridged. Does any one have a pic or diagram of the internal wiring ,Brushes etc i could look at ?

We have pics in the workshop manual but the detail is very poor.

Cheers

email (option): wpgarage@xtra.co.nz

I have just spent an age sorting out my dynamo on my M20 (I got a lot of help from this site).

I presume that the dynamo is not on the bike as you got it to motor (unless you have taken the drive chain off), so I guess you are using something else to drive the dynamo.

On my bike, the solid state voltage regulator had failed. This was the first problem. There are lots of YouTube videos on how to check this.

My second problem was that the dynamo was not putting out a charge.

First, check the bike to see if it is positive or negative earth (which terminal of the battery is earthed).

Second, flash the dynamo for whichever the bike is set up for (positive or negative earth)

Third, check the output of the dynamo at just over tick over (bridging D and F - make sure the connections between the two are really good). The voltmeter needs to be set to DC and not AC.

Forth, give the commutator a really good clean (I used electrical cleaner from a spray can) and check the bush springs and the length of the brushes.

My problem was that a load of dirt had built up in the slots of the commutator. I carefully scratched them out using a long pin.

Hopefully, flashing the dynamo will restore its residual magnetism and that is all you need to do. Be careful, if you have a solid state voltage regulator you need to flash it correctly or you may burn it out (they come in positive or negative earth versions and should be fused at say 15 Amp). From memory, if you have taken the armature out of the dynamo, the you need to flash it.

The Technical Section explains how to flash a dynamo, but look at the website "matchlessclueless" too or Google how to flash a Lucas Dynamo.

Google "BSA Service Sheet 808" this gives A, B and M wiring diagrams. But again pay attention to whether the bike is positive or negative earth as you may not know what someone has done in the past.

Apologies in advance if you already know all this.

Regards

Pat

email (option): sacombsashtrees@hotmail.com

Just read your post again.

I will look at my A10 dynamo's internal wiring (which wires go to which brush) and re-post (got to go to work now).

My guess is that you need to flash it.

Don't over rev or over spin the dynamo too fast when checking the voltage.

email (option): sacombsashtrees@hotmail.com

Just had a look at my A10, which is a 1962 swinging arm model. However, the internal wiring is the same as my WM20.

Looking at the dynamo, on the bike, but with the dynamo cover off, the wiring is as follows.

The right hand brush is a straight wire to "D".

There are two slots in my dynamo. The wire exiting the slot on the right hand side is connected via a screw to the left hand brush. The connection is to the bit of dynamo body that houses the bearing and the commutator.

The wire exiting the left hand slot is a straight wire to "F".

On my M20, the left hand brush is a straight wire to "D". My M20 has only one slot. One wire comes out of the slot and is connected via a screw to the right hand brush. The other wire comes out of the slot and is a straight wire to "F".

When I use the term "straight wire", I mean not having any other connection to the body of the dynamo that houses the bearing and commutator.

Hope this helps.

However, please get someone else to check their A10 too as mine is a 1962 model and your dynamo may look different. The concept, I guess is the same, field winding wire straight to "F" - dynamo winding to both brushes via the commutator and out one brush straight to "D".

Regards

Pat

email (option): sacombsashtrees@hotmail.com

Another caveat. As I could not see inside the dynamo (M20 or A10), the exiting wires from the two slots could have been reversed!!! I do not think that they have though. However, who knows what has happened to your dynamo in the past.

Regards

Pat

email (option): sacombsashtrees@hotmail.com

Thanks Pat
I will check it with your details when i get time.

email (option): wpgarage@xtra.co.nz

Hi Pat
Our generator as it is in the bike the brushes are up and down rather than left and right.I have added a pic with "D" and "F" at the top . Would your left and right match the photo ?

email (option): wpgarage@xtra.co.nz

It is an earlier dynamo than the one on my A10.

However, the principle should be the same.

Grey wire on the left marked "F" goes straight to the voltage regulator.

Wire from the brush on the left goes straight to "D" on the voltage regulator.

Wire from the brush on the right that is connected to the grey wire on the right of the picture; connect the grey wire to the screw on the top of the bearing housing (the flat headed screw on the grey bit, not the mushroom headed screw on the brown bit).

Not sure, but strictly speaking, I think the wire from the brush on the right should go to this flat head screw, then the grey wire exiting "D" should also attach to the same flat head screw. Not sure if it makes much difference.

Test the generator with the voltage regulator disconnected. Don't over rev or overspin the dynamo when testing

Always fit a say, 15 Amp fuse on the "power" lead (not the earth lead) from the battery.

By far the best thing to do is to check against the same dynamo from another bike that has a working dynamo......not always possible! Have you got a picture of the dynamo end cap?

Regards

Pat

email (option): sacombsashtrees@hotmail.com