Dynamo Commutator Connections

wilko · Post by **wilko** » Mon Feb 13, 2012 1:16 am

The two on the right are for the regulator and dynamo end cap. The one on the left is conventional. Sorry about size, i did resize it on photobucket but it obviously didn't work!

fump · Post by **fump** » Mon Feb 13, 2012 8:23 am

Mine did have the dreaded signs of overheating, with a sprinkling of solder "powder" on areas near the commutator.
Has anyone here ever tried a DIY re-wind? I found mention of it on a BSA forum, but not enough detail for me to give it a go. Though I have nothing to lose, but a few hours on a rainy day.Edited by - fump on 13 Feb 2012 08:24:59 AM

aobp11 · Post by **aobp11** » Mon Feb 13, 2012 10:14 am

At an oldtimer happening I saw an experienced person demonstrating the rewinding process.
A few hours when you do this for the first time? No way. Already the preparation alone will take a lot of time. What is the winding scheme? Where do you get the magnetic wire? Which gauge and which length? Which isolation between winding and metal? How to fix the windings in the grooves; epoxy, impregnated wooden spines? Can you still use the old commutator, mechanically and electrically (maybe so far corroded that soldering is impossible)? For convenience you have to remove the commutator anyway and get it back in place stiff enough.
I have successfully resoldered loose wires to the segments, but rewinding no.
Albert

wilko · Post by **wilko** » Mon Feb 13, 2012 9:33 pm

I sent the wrong pic!

en7jos · Post by **en7jos** » Tue Feb 14, 2012 1:12 am

Hi Roger - my advice is to send your dynamo off to Tony Cooper (see details in the 'Recomendations' section of the forum) and let him do a proper job for you. He recently looked after both my dynamo and mag, did a splendid job and not so expensive. Some jobs just aren't worth attempting yourself in my opinion unless you have the right tools, experience, spares and know-how.

Thanks for the pic of the hollow connectors Wilko; I see what Rob meant now. I was forgetting that this type is also used on the reg as well as in the end of the dynamo.

fump · Post by **fump** » Tue Feb 14, 2012 6:49 am

James and Albert thanks for your comments.........

You are probably right Albert but it cannot be so very hard to copy the original surely .......but I have said that kind of thing before and ended with disaster.

James the freight cost from NZ to Halesowen would be prohibitive !

aobp11 · Post by **aobp11** » Tue Feb 14, 2012 10:18 am

quote: Could it be, as some here have suggested the Field coil could be wired oposite to the correct way ?
Hi Roger, so the dynamo was dead already when you got the bike? If the field coil wires were interchanged than the dynamo would still motor (but against the arrow) and it would try to regulate the output voltage to exactly zero!
Like also Groily mentioned before, resoldering the segments is not easy. If you still want to give it a try, get both (!) wire ends out of the segment groove, clean everything from flux, insulation, old solder, and then resolder again. But your armature probably has been so hot that the copper wires have become black and brittle.
If you order a new armature, be sure to have the correct type for your dynamo. E3AR? New 6V for E3N are not that expensive at all. Conversion to 12 V windings seems problematic (James?).
Albert

en7jos · Post by **en7jos** » Wed Feb 15, 2012 1:05 am

All options considered here in Hong Kong, posting my dynamo back and forth to the UK (to Tony Cooper) was still the best. Postage wasn't exactly cheap, but not really prohibitive. I did get someone to bring it back to HK in their hand luggage when they came to visit though! You can always remove the armature and just send the other bits, that should save some weight on the way out at least. Having lived in the back-of-beyond when it comes to getting old bike bits for the last few years, I've got used to factoring in shipping charges into any purchase, but find that not paying the 20% UK VAT more than offsets shipping charges usually (apart from some new fork tubes from JSL - ouch!). Call it Plan B though if you like...

As Albert said, 12v armature coils are not an option on the shorter E3NL dynamo's as no-one seems to make them. That said, there is also no point as the 6v armature (in good condition at least!) gives more than enough volts to run a 12 system (with a suitable reg of course). At least that's my experience.

James

fump · Post by **fump** » Wed Feb 15, 2012 9:22 am

Thanks James and Albert for your inputs, I am certainly tempted to give it a try. The big dis-insentive is having to take the B***d* chaincase off again!But the idea certainly interests me, and thats really why I bought an old simple bike, to DIY.

Yes I bought the bike in November last year and I believe it was not working when I bought it.......like so many other things with this bike.

The armature wire appeared to be okay but there was only a very slight burnt insulation smell that I remember so well from years ago, when removing a burnt out motor from a Radar scanner aerial, on a ship in heavy weather. That certainly disturbs the stomach!