Dynamo Light Problem

[tnort...@gmail.com]

My wife's SP hub is putting out power but the light does not work . I get a "flash" now and then.  I do get continuity through the system. 

Here is a pic. Not sure if this will help. 

But help would be great! 

Tom

NE Ohio 

[Alistair Spence]

Tell us more about what looks like exposed wire, just to the left of where the light mounts to the fork crown bracket. Another photo, taken from a different angle, might help.

Alistair Spence,

Seattle, WA

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[tnort...@gmail.com]

That is just the ground wire. It was attached when I checked continuity. I did a bit of disassembly to see if any wires were loose.

Tom

NE Ohio 

[Alistair Spence]

So it's the return from the light, completing the circuit back to the hub? If that exposed wire touches any metal then it's going to create a short. Over rough roads that could explain the intermittent flashes you're seeing.

Alistair

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Alistair Spence,

Seattle, WA.

[tnort...@gmail.com]

I am not ashamed to say that electrical confuses me at times! 

Tomorrow I will look at my front light setup and compare the two wiring runs. And will report back!

Tom

[Alistair Spence]

On Tue, Nov 25, 2025 at 5:42 PM tnort...@gmail.com <tnort...@gmail.com> wrote:

I am not ashamed to say that electrical confuses me at times! 

You are not alone in feeling that way, I for one can vouch for that. 

Btw, if that exposed wire is the issue you should be able to test it by spinning the wheel and touching the wire to some exposed metal on the frame/fork/light bracket etc. Light should go off upon contact, and back on when you lift the wire off the metal.

Alistair

 

[tnort...@gmail.com]

Fixed!

Took everything apart and put it back together and it works! 

Guessing there was a faulty connecting somewhere  between the headlight and taillight. 

Tom

NE Ohio