E3L circuit question.

[JFerg]

I have a miscreant E3L dynamo that won't charge.  Motors beautifully, and all obvious things are fine.

It's an early version, 3rd brush type with cutout, and has 3 terminals, marked "+", being +6V supply from the battery, "FD", being the field winding, and "WL", and I don't know what that stands for.  Can anyone enlighten me on that?

I've been through all of my reference stuff; from Radco's book through my (indexed) copies of Classic Bike, Classic Motorcycle, Classic Mechanics, to my original Lucas books, which include "Running Instructions for the Lucas 1930 Dynamo Lighting Sets", and can find nothing which actually shows three terminals on a dynamo.  I cannot find the wiring diagram I wired the bike to, however, and that's a pain.

The internal wiring resistances are so low (although they are not to frame) that I can't deduce anything with confidence.  What I have doesn't work anyway, so is of questionable value.

So can someone in the group tell me what the "WL" terminal does?

thanks,

JFerg

[JFerg]

Amazing how things work, isn't it?  No sooner had I posted the previous than I was inspired to search another reference source and found Lucas Drawing No. MA252-A1.

"WL" is the Warning Light, the ignition idiot light, fed via a brown wire if you're a conkers-obsessive.

cheers,

JFerg

[rogerwilko]

So you have coil ignition?

[JFerg]

Yes, coil ignition, with points on the end of the E3L.

And despite knowing what "WL" stands for, stripping, checking everything from first principles and swapping every suspect for another from "stock", the damn thing will still motor happily. but not generate.  I don't have access to a known good one, either.

Suspect I am doing something fundamentally wrong, but can't see it.

JFerg

[Rex]

Sucking eggs, and all that, but have you "flashed" it before trying it?

[rogerwilko]

And is it motoring in the right direction? I'm not familiar with the old 3 brush wiring but with 2 brush just reverse the field wires.

[Rex]

Also with the three brush set-up, is the third brush too far over and over-regulating the output to the point of non-existent?

Convert to two brush and fit a Manortec reg, would be my advice.

[chaterlea25]

HI Jferg,
The fact that a dynamo motors is no guarantee that it will generate
If the dyno motors in the same direction as driven then its connected ok, otherwise swop the field connections

To  check the armature  properly it needs doing on a "growler tester"
A home check you can do is to connect the armature via the brushes at 180 deg to each other in series with a small wattage (say15w) 6 volt bulb and battery,
carefully turn the armature one segment at a time and watch how the bulb brightens and dims as you turn, when the brushes are on each segment note how bright th bulb is, if there is a broken connection in the armature this test will normally show it up, as the bulb will not light or be very dim compared to other positions,
If the bulb lights full brightness then theres a short in the windings
Sometimes  the armature can be persuaded into life by resoldering the connections to the commutator
It needs a big wattage iron to  do this sucessfully (80-100w)

Amen to scrapping the 3rd brush and fitting a "proper reg"

HTH
John O R

[JFerg]

Am collecting the growler tomorrow, but I suspect no problem there; although I don't have a "known good" replacement, two half-decent looking spares behave same as the original. 

3rd brush too far over is a very interesting suggestion; when the workshop dries out from this morning's flooding, I'll try that.

cheers,
JFerg

[JFerg]

Congratulations, Rex, for being closest to the mark.

I adjusted the third brush and the problem vanished.  Further investigation showed that the brush holder had shed the brass stud moulded into it, plus the insulation around it, and that was shorting to frame.  Tomorrow I will either repair, which will be tricky, or make a new one from scratch.

cheers and thanks all.

JFerg