Technical > Lighting and Electronics

Edlux II front light stopped working?

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Dave B:
Hi, on my Thorn Nomad II I have a SON dynamo hub powering just a front light Edlux II. Itís suddenly stopped working after many years of use . Checked the connectors but still no light! Is it the light , or is it the hub? Is  there anyway of findings out the cause of the fault?

From experience of a family full of bikes on various hub dynamos and the good news is that it is probably the cheapest component that has failed, namely the cable.

But obviously you need to check to be sure. And this can be done without fancy equipment in most cases.

First check your dynamo is working. You will need a low voltage lightbulb. Although your hub probably puts out 6v you may be able to test this with a lower volt torch lightbulb e.g at 3v or a car light bulb at 12v. I have an old EverReady 3v battery bike lamp (batteries removed)from the early 90s to which Iíve attached a couple of garden tie wires to the copper connectors in the lamp fittings and put the lamp in on position so the circuit will light when voltage is applied. Connect or hold the other 2 ends to the Dynamo output connection at the hub. Spin the wheel lightly and if bulb lights you know hub is good.

To test the lamp you need to pass voltage into it. Although the dynamo is 6v you can test this with less voltage. If you have a powerbank for a USB device and an old usb cable you donít mind killing you can chop the non powerbank end off (while not connected to anything!)and expose the individual inner cables. YouĎll need to strip back 2 of potentially 4 cables which are carrying the power. I will see if I can find my cable and upload as example of which 2 colour cables mine was. Presumably this is standard but I only ever chopped one cable so cannot compare.
Some LED lamps are not fussy which is positive or negative from power source. Others are a bit more fussy and only take power one way around. If you apply power and nothing happens then try again reversing cables connected. If lamp lights, then all is good.

At this point you know if either hub or lamp are toast. And hopefully you have proved both are working so you just need to replace the cable between both hub and lamp.

As mentioned at opening, cable fatigue is most likely culprit. So without all the testing you could just try a new length of cable and seeing if that works. It doesnít have to be bike specific cable. Old speaker cable or even a length of electric flex. would work to test at very least. One of my bikes has rear dynamo light wired with loudspeaker cable for over 5 years and still working.

Dave B:
Thanks for that most comprehensive advice , I will have play and see if I can find the fault.

Good reply from Steve, I haven't got a lot to add other than that all my dynamo failures have been related to the connectors - when I say all, that's just three in thirty years!  Are you using the spade version of the light, or the more recent jack plug connector?  I've had the spade type fail when the cable has broken off the spade, probably fatigue, but might be worth removing the heat shrink to have a proper look.   I've also had the female part of the jack plug fail, no reason I can see, just stopped working, rather annoying as there's no repair, wipes out any advantage it has.
I've never had an issue with my Edelux lights, but know someone who had a problem with the switch,  though it might have been that they couldn't turn it off - it needed the black ring/switch replacing, though they discovered this by testing it with a magnet.

Here's example photos of what I used to test hub and lamp if working.

Using good old Everready bike lamp without batteries but with garden wire on the terminals. Would work with an old torch or even wires held by hand against the terminals of bulb if you can hold steadily:

For using a power bank to power lights when old bottle dynamo failed, I cut old USB cable to expose the cables. In my case I added spade connectors to make it easier to join to existing dynamo circuit. But for testing purposes, exposed wires would work. It looks like it was red and black were the power carrying cable colours in my case. But I have no idea if this is standard cable colouring convention, so if you have more than 2 cables making your own such USB conversion, then take care to check if you have a 4 core wire especially if colours are different to mine.

and finally, it doesn't have to be dynamo cable... at least for a short term fix. But good quality dynamo cable ought to have more flexible/less brittle internal wires. BUT I have had success in using cuts from this old speaker cable which are still going strong years later. Mine is a bit thicker than typical dynamo cable, but otherwise works a treat. No promises an guarantees for old cable other members might have laying around, but who knows, perhaps you have something that performs better than bike shop dynamo specific cable in your odds and ends drawer of offcuts?


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