CAV DEL type dynamo question

[Mark McKibbin]

Digital voltmeters detect all sorts of stray voltages. Seven dynamos do seem prone to lose magnetisation. Re polarisation  is often helpful.
It is a long shot but if the field is connected backwards the dynamo generates an output which cancels the field so it will never get going.
It is very unlikely the armature is wound wrong . Even if given a bare armature and the wrong one as a pattern I think the comm section numbers is different, and one has  armature poles in a slight helix form..

I have found that as well until I bought a good one (Fluke) it is rock solid in an electrically noisy environment like a 7's charging system, I have re polarised it and I assume as I have run it as a motor that would have re polarised it again.

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Mark, Have you another dynamo that you know is good that you can swap over armatures over with. That way ar least you’re will know if the problem is with the armature.

John Mason

Good Idea John,
That will be on today's list.