Vintage Miller Dynamo rear light problem

mikkybgs
mikkybgs Posts: 78
edited February 2014 in Workshop
Hi,

Apologies if this is the wrong section but I wasn't sure where to post this!

I have recently acquired a vintage bike that is fitted with a Miller Dynamo with front and rear lamps.

The front is working fine but I can not get the back to work and I'm not sure if I'm missing something that is obvious.

It had no bulb in so I have tried two bulbs. The bulb which i expected to work was 6v 6w 1a. It is halogen though, does that make a difference?

All the wiring seems to be fine.

The reason I think I may be missing something is I've never worked with a dynamo before and when I try a rear bulb the front no longer works so is the dynamo not generating enough power to light both bulbs?

Any advice would be greatly appreciated.

Comments

  • mikkybgs
    mikkybgs Posts: 78
    Also it is worth noting that the rear bulb has to be a push and the halogen was the only one I could find that was at 6v 6w 1a.
  • alan_sherman
    alan_sherman Posts: 1,157
    Have alook through peter white's website. Seem to be the dynamo knowledge centre on the web.

    http://www.peterwhitecycles.com/taillights.asp
  • term1te
    term1te Posts: 1,462
    Most dynamo systems only produce 3W at 6v, so your 6W bulb probably can't draw enough power to glow, especially if you've got a front light as well.

    With standard incandescent bulbs you have 2.4W at the front and 0.6W at the rear.

    You could take the front bulb out and swap it into the rear fitting to check the wiring?

    I'd try a 6V 0.6W bulb in the rear light, if you are confident the wiring is OK.
    The Master
    The Moser
    The VN
  • mikkybgs
    mikkybgs Posts: 78
    Term1te wrote:
    Most dynamo systems only produce 3W at 6v, so your 6W bulb probably can't draw enough power to glow, especially if you've got a front light as well.

    With standard incandescent bulbs you have 2.4W at the front and 0.6W at the rear.

    You could take the front bulb out and swap it into the rear fitting to check the wiring?

    I'd try a 6V 0.6W bulb in the rear light, if you are confident the wiring is OK.

    This is good advice. I dont know where I got the information to get the 6w bulb but it would certainly seem it's too much.

    Unfortunatly I can't try the bulb from the front in the tail light as it is a screw in and the rear is push in.

    Your suggestion seems to be the most likely cause of it not working due to the front working then when i put the rear bulb in they both stop working.

    I'll seek out a more suitable bulb and give it a go.

    Many thanks.
  • MichaelW
    MichaelW Posts: 2,164
    touch the wires to a bulb with no lamp housing. If it works, you have a problem with the housing connectors.
  • mikkybgs
    mikkybgs Posts: 78
    mikkybgs wrote:
    Term1te wrote:
    Most dynamo systems only produce 3W at 6v, so your 6W bulb probably can't draw enough power to glow, especially if you've got a front light as well.

    With standard incandescent bulbs you have 2.4W at the front and 0.6W at the rear.

    You could take the front bulb out and swap it into the rear fitting to check the wiring?

    I'd try a 6V 0.6W bulb in the rear light, if you are confident the wiring is OK.

    This is good advice. I dont know where I got the information to get the 6w bulb but it would certainly seem it's too much.

    Unfortunatly I can't try the bulb from the front in the tail light as it is a screw in and the rear is push in.

    Your suggestion seems to be the most likely cause of it not working due to the front working then when i put the rear bulb in they both stop working.

    I'll seek out a more suitable bulb and give it a go.

    Many thanks.

    Really struggling to find a 0.6w bulb that is push in not screw in.
    If anyone has any suggestions i'd appreciate the advice!

    I'm suspecting this dynamo and light system is from the 40s/50s so maybe they just don't make these bulbs anymore?
    MichaelW wrote:
    touch the wires to a bulb with no lamp housing. If it works, you have a problem with the housing connectors.
    If there is just one wire would this work? Does it not need to create a circuit and thats what the housing acts as?
  • term1te
    term1te Posts: 1,462
    If you only have one wire, the frame of the bike acts as the other wire.

    Does this look like the bulb you need? http://www.reallyusefulbikes.co.uk/_shop/bulbs/6v-06w-bayonet-bulb-/ If it is, 49p seems like a bargain, I'd get a few in case one blows.

    For some unknown reason, I have a 2.4 and a 3W dynamo bulbs in my office desk draw, they've been there for as long as I can remember. Bound to come in useful one day, even though I now have LED dynamo lights.
    The Master
    The Moser
    The VN
  • mikkybgs
    mikkybgs Posts: 78
    Term1te wrote:
    If you only have one wire, the frame of the bike acts as the other wire.

    Does this look like the bulb you need? http://www.reallyusefulbikes.co.uk/_shop/bulbs/6v-06w-bayonet-bulb-/ If it is, 49p seems like a bargain, I'd get a few in case one blows.

    For some unknown reason, I have a 2.4 and a 3W dynamo bulbs in my office desk draw, they've been there for as long as I can remember. Bound to come in useful one day, even though I now have LED dynamo lights.

    Thanks for the reply, unfortunatly I don't think that bulb would be suitable as the bayonet is too low and the bulb would go too far into the light. It's hard to explain so I've uploaded some photos of the system and the light fitting.

    Perhaps someone recognises it?

    The read dynamo and the light:
    http://i61.tinypic.com/9q9us3.jpg

    The light insert where you put the bulb:
    http://i60.tinypic.com/3508708.jpg

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