Dyno light problems

[The Family Cyclist]

Diagnostic murder! One of the wires....yes the one that involves taking all the wire off has snapped. Will be getting tiny heat shrink and soldering the end on to a new bit of the wire and hopefully that will sort it....so long as I can get the whole thing back together. If it works and I'll take pictures I may ask someone on here if I can email and then they can upload it for me.

[Brucey]

ah!

[The Family Cyclist]

One question that does puzzle me slightly I got no reading of resistance from the wire. Well multi metre shows 1 which is infinite along the wire when outstretched although it was touching itself as still had loose coils where I had unwound it.

[Kim]

It's probably coated in a varnish, so it can be coiled up tightly without any bulky insulation.  Normal method is to give it a rub with some sandpaper before making a connection.

[jsabine]

You can of course simply replace the centre part of the hub, but it usually costs almost as much as a whole new hub.

Diagnostic murder! One of the wires....yes the one that involves taking all the wire off has snapped. Will be getting tiny heat shrink and soldering the end on to a new bit of the wire and hopefully that will sort it....so long as I can get the whole thing back together.

Which model of hub is it? If it turns out to be completely buggered, I've got a couple of NOS DH-3N71s - if they'd be suitable either as replacements or to cannibalise the innards, they wouldn't be expensive ...

[The Family Cyclist]

It's a DH 3N72.

I'm going to get it back together to a stage where I can test it. I'm pretty determined to fix it having got this far but I'll let you know if it's a no go. Their are a few kinks in the wire so wondering if these may have gone through the insulation and shorting. I was wondering about how it worked with what looked to be uninsulated wire but this is all a learning curve

[The Family Cyclist]

Update - hubs dead. Rewinders can't as wire too thin. Couldn't ever see what was wrong but must have been a break in the wire. Have put an appeal in the wanted section

[interested]

Update - hubs dead. Rewinders can't as wire too thin. Couldn't ever see what was wrong but must have been a break in the wire. Have put an appeal in the wanted section

You can buy the "internal assembly" Shimano spare part number "Y-2YX 98010" here for around 37 Euro+PP:
http://bicikli.de/shop/SHIMANO-spare-part-Y-2YX98010-DH-3N72-INTERNAL-ASSEMBLY-AXLE-LENGTH-108MM-FOR-DH-3N72-Shimano-Code-Y2YX98010 
 
I would probably replace the ball bearings too and pack them with a lot of grease. See the Shimano exploded diagram for size etc.

I would also take the old "internal assembly" apart and salvage the hidden cone. The L+R cone ought to be identical on Shimano non-disc 3W dynamo hubs, so it can be used as a spare.

As for the connection wire (the one that might snap when taking the stator apart, it is made of copper on the models I have seen, but with a rather thick coating. Here is a picture of the wire with the coating scraped off so you can see the copper:
https://www.flickr.com/photos/28712360@N08/9486590101/in/album-72157635030656224/ 

[The Family Cyclist]

Thanks.. does anyone know of the internals for a 3n71 will fit a 72?

[jsabine]

Found a German parts diagram that says the part number for the 71 is Y-2ZR 98010, while the listing linked above says the 72 is Y-2YX 98010

Aha. Similar parts diagram for the 72 confirms the part number, and gives a blank for interchangeability. Whether that means it's a no-go, or simply not approved, I don't know. The picture looks similar ....

(No link as on phone)

[Brucey]

IIRC the bearings are different. It may be possible to cobble something together, but you are probably best off using the hub end face, bearings, cones etc from the '72.

cheers