I'm having a strange problem, somewhere in my lighting system. It's a SON dynohub and a B&M Luxos U and something isn't working, but I can't work out what. Having spent a couple of hours with my Grandad and a whole barrage of electronic testing gizmos this afternoon, we couldn't find any problems with the dynamo, the wires or the light. The only suggestion we came up with was to leave it connected and see if it charges the cache batteries after a few rides.... but It's been connected and switched off for a few days and not charged so we're stumped. They're both still under warranty because I've only had them a year, but I'm not entirely sure which one to send back. And I'd rather not if I can help it - they have to go all the way back to Germany.
Just to be clear, on test, you got the dynamo working (a currant coming from it) and you got the light LED working, but you couldn't get the battery cache charged, right? If that was the case, I think the light unit is suspect. My understanding is the dynamo is a passive element, just chucking out juice. The complicated bit is the Luxos on the other end.
CREPELLO wrote:Just to be clear, on test, you got the dynamo working (a currant coming from it) and you got the light LED working, but you couldn't get the battery cache charged, right? If that was the case, I think the light unit is suspect. My understanding is the dynamo is a passive element, just chucking out juice. The complicated bit is the Luxos on the other end.
No, the light and the charger don't work at all. I can't pretend to know what my Grandad's testing gizmos do but he said something like there's a "big resistance" in the light but something is getting through. I told him it had a cache battery he said "it coud be that that's discharged completely, have you tried leaving it connected but off for a while to charge it?" Just before it went completely, the light was flickering even at relatively high speeds and prior to that the charging from the USB was intermittent (I got 13% over 40 miles where previously I've had 26% over 4 miles including some walking). Nothing happened to it, it just wouldn't turn on the next day, so I left it connected for a few days in the hope that it might be the battery, but it didn't work so I sent it to Grandad's house.
As you said, I didn't really think there was much to go wrong in a dynamo, but the idea that the cache battery might not be charging, PLUS I would have thought, the Luxos primarily being a light and not a charger would mean that the light would come first... has made me suspect the dynamo... but my screwdriver test says it's working and Grandad's gizmos say it's working.
I might just send the light back and hope it's that. That would be much cheaper than stripping and rebuilding the wheel.
From what you say, its sounds highly likely to be the light. You could send it back directly to Amba marketing (B&M's UK distributor) to save a bit of time. Talk to them - they're very helpful.
cache battery? u mean the standlight ( capacitor ) for when the wheel not turning but the light still on? I would guess if thats has gone then could be a short? though I dont really know what happens when capacitors go wrong.
I take it that it used to work OK? With dynamo systems, it's best to strip everything back to the bare minimum, and start adding complications until it stops working
Take the light off the frame, turn the bike upside down, plug the front light only into the hub (so the wires are only touching at the hub, and there's no rear light or anything in the USB port), and spin the wheel.
If it lights up OK, the hub is OK and the light is OK, so it's either the wiring or the rear light.
If it doesn't light, try a different front light. Borrow one, or you could use a couple of bits of wire and a torch bulb (though that's a bit awkward without going so far as soldering on a couple of female spade terminals). 6.35mm ones for cars from Halfords or Maplins are near enough to work, though you may want to squeeze them a little with a pair of pliers.
If the other light doesn't work, it's probably the hub. Try measuring the resistance between the two spade terminals (should be low enough to set a continuity beeper off), and the AC voltage when spinning the wheel (should get up to 10V quite easily, spinning the wheel by hand). SON hubs are returned via St John Street cycles in Bridgwater rather than directly.
If the Luxos doesn't work, but the alternative light does, it's the Luxos that has to go back.
If the Luxos works off the bike, reattach it, still with no rear light or anything in the USB, and see if it still works. If it doesn't, you are managing to get a short somewhere on the wire run. If it does work, leave it turned on, and go ride for a mile or two. Does the standlight show when you stop? If it doesn't, it needs to go back with the additional info.
Then it's a longer ride, and checking that the "high beam" works (if it does, the internal battery is charging OK), and then adding the rear light (if any) back.
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