Cross wiring bikes to check charging system.

[jj.palmer]

Thanks for that Paul, just to clarify, the bike is positive earthed therefore the two setups to check the direction of rotation I have shown in the
attached drawing, are these correct ?

Sorry for the attachment being on its side, I have rotated the attachment at source but it still does not correct it, any advice would be appreciated.

Thanks again
John P.

[admin]

er .... you don't mess with the wiring to get postive/negative earth. You "flash" the dynamo field correctly to get that right.

Swapping the field wires (or swapping the brushes over - leaving them connected, if their wires are long enough) will change the rotation.

If the KH rotates the dynamo in the same direction as the NH, then wire the dynamos the same.

Clean the commutator completely. Degrease the brushes.

[jj.palmer]

If the wires to the field windings are connected to terminals "F" and "D" the wrong way around and then the dynamo is run would it do any damage to the field windings etc..

John, whilst I have your attention, when I add attachments they are seen as being on their side, even if I compensate the orientation at source on the computer it does not make any difference. I am running Windows 10, any advice please.

Regards
John P.

[admin]

It has to do with how the software handles the exif tag. I thought the forum handled this - but not every image has the correct implementation.
Simply put, your software tags the image so that any viewer will simply orientate "your" view of the document. Exif doesn't change the orientation of the image itself, as such.
You usually need to re-orientate it, in an image viewer, and re-save it

hmm I don't know if you will damage anything with those sort of wrong connections, within your dynamo.
I have done it a few times without damage, but it only took some short test runs to figure it out.

I do know that not regulating the output of the dynamo correctly will destroy the armature, after a short while.

[jj.palmer]

Thanks everyone, the dynamo and the whole charging system is now working fine, showing slightly positive on the ammeter when the headlight is on.
I did all that was suggested, cleaned commutator, checked direction of rotation, flashed field windings etc. which one caused the dynamo to work again I don't know, possibly a combination of them all.
The benifit when things go wrong is the motivation it gives to learn more about that particular subject, you always know more at the end than at the beginning.
Thanks again,

John P.

[paul.jameson]

Yes, John P, your wiring diagrams look fine.

John N. Flashing the dynamo is indeed the normal way to polarise it. But swapping the field coil terminals will change direction of rotation whilst maintaining the original direction of magnetic flux in the dynamo body. Running the dynamo as a motor will have the same effect in terms of setting the direction of magnetic flux as flashing it will. The problem is that you need a certain amount of magnetic flux in a dynamo to start the thing charging. The flux dissipates over time which is why people recommend re-flashing. 99% of the time this works well but occasionally you find a dynamo which likes its magnetic flux a particular way round. This is probably due to nearby magnetic fields - such as the one caused by the magnet in the magneto. If you get one of these awkward dynamos, they can change polarity if you leave them out of use for a while and you have previously flashed them the opposite way from the one they prefer. That is why I advise changing the field coil connections to get the direction of rotation correct. If the dynamo is being awkward, it pays to be careful.
Incidentally, I picked this lot up about 25 years ago when I was selling electronic regulators through Single Spares. The regulator manufacturer was one Marco Boelis who has recently rebuilt a superb 600cc Square Four - details on this forum - with much improved electrics...........

[jj.palmer]

Having fitted and checked the dynamo for charging as my previous post I proceeded to check the screws for tightness and unfortunately stripped one of the threads in the dynamo of the screws that go in from the timing side.
The thread measure 3/16 inch x 32 tpi this matches with 3/16 inch BSF, could anyone confirm this as I need to get a thread repair kit on order.

Regards
John P.

[jj.palmer]

Now repaired, the 3 screws into the dynamo from the timing side are compatible with a 3/16 inch x 32 tpi helical insert.

John P.