installing busch & Muller dynamo light set- any help please?

[fiverbag]

Hello,
I currently run a shimana hub dynamo (6v 3.0w) connected to a busch & Muller lumotec plus front (though I think I shall soon be changing it for a Lumotec IQ Cyo) light which then wires up to a rear, rack mounted light. I have no trouble connecting and running the front light through the dynamo but as soon as I wire the rear into the lumotec, it stops working. I know this is not due to too little power comming from the dynamo because when the rear is connected, all resistance in the hub dissapears- similar to when it is switched off. I have tried various different combinations of where I plug in the wires to no avail. Can anyone point me in the direction of where help for setting up and installing these lights might be?- Hopefully I'm missing something. I have looked all over the internet and can only find advice on installing the front, which is all pretty self explanitory. Any advice or help in finding advice would be much appriciated- if anyone can think of where a video tutorial may be that would be amazing!

Many thanks
Craig. Norwich.

[ed_b]

Hi, I fear I'm not going to be massive amounts of help here, but can you clarify

it stops working

? Do you mean when you connect the back light the back light stops working, or that the front light does? Or maybe both? And can you specify what back light you're using?

Assume you've tried making both work from a battery on the workbench?

I'm not whizz enough with electronics to comment with confidence on the drop in resistance at the dynamo, but surely means the back light is causing a break in the circuit? Unfort I can't see from the B&M website what connection system they use, but ime using the bike as the ground/return for a lighting system is usually spotty at the best, especially on the back with many connections for the leccy to bridge (eg, bike to carrier). I always rig a wired ground (which can be a bit of a faff sometimes) and haven't had issues. If your system is relying on the bike's connectivity, you could try that - just make sure you've got good, multicore wire, and rig the lights parallel, not in series.(B&M being state of the art might have realised this already - my lights are always from bootsales!)

Hope others can help more than me, and good luck with it.

[trieste]

http://www.bumm.de/service/download/anleitungen.html

Have a look at the above link which list the instructions for each model.

[gilesjuk]

Assume you've tried making both work from a battery on the workbench?

They run off AC, there's no AC batteries some lights (Supernova) supply DC to their back lights as the electronics are all contained in the front light.

It could be a duff light or duff wire. If you stick a multimeter across the wires on the rear light, if there's 0 ohms resistance then there's a short somewhere.

[andrew_s]

The hub is earthed to the frame, as are both of the lights unless you are using an insulating bracket. If one of them is connected the wrong way round, you'll short out the dynamo.

iirc there is a single wire on the front light for connecting to the rear light. If you want a double wire, the other strand should connect the two lamp mounting points or labelled earth connectors.

If the rear cabling looks OK, try swapping over the wires in the dynamo plug.

The rear light should be powered via a plug on or cable from the front light. Instructions to connect direct to the hub in parallel are only really applicable to incandescent bulb lights.

[ed_b]

@gilesjuk,

They run off AC, there's no AC batteries

Point taken. My lights are all incandescent, no-electronics versions, so they work just as well on DC.

@andrew_s, thanks for the correction.

[CREPELLO]

Assume you've tried making both work from a battery on the workbench?

They run off AC, there's no AC batteries some lights (Supernova) supply DC to their back lights as the electronics are all contained in the front light.

Hmm, not sure about that as an absolute fact. The OP reffers to a LUMOTEC PLUS, which is a halogen light if I'm not mistaken. Second, many LED lights can run off DC sources (battery lights spring to mind), B&M certainly can - my Cyo and IQ Fly have both been driven off my Lightspin dyno, which is DC.

I think I'd try the battery test.