LUMOTEC/DYNOHUB front light not working. Have tester and am willing to learn!

[kitchenman]

I have the lamp on my desk and a tester in my bag. Can I test the lamp at my desk? Is there anything else that I need? ... thanks ..

 

[shemozzle999]

What model front light?
Is it one with a sensor?
Any chance of a photo?
On a simple lamp it is just a quick check with a meter to see if the bulb and holder connections are alright.
This can be done on the resistance ranges to see if it gives a lowish reading.

If you know the wattage of the light and the voltage of the dynamo from ohm's law:

Square the Voltage in volts, divided by the Power of the bulb in watts this will give you the expected resistance reading of the bulb in ohm's.

 

[kitchenman]

Yes, its the one with the sensor (Oval Senso Plus) ..
I've taken a photo but my computer has decided not to recognise my phone! ...I'll try again from home ...
I dont mind by-passing the sensor circuit. Be nice just to get the light on! ..

Photos:

 

[shemozzle999]

I'm not sure how to test these, but suggest you look here:

My first guess would be that the led is shot, I would source a replacement first to eliminate that before playing around with the circuit board.

You will need to Google translate this page

Busch & Müller: FAQ

 

[kitchenman]

nice one. Thanks ..

 

[shemozzle999]

Apparently they do two types, a diode version or a halogen bulb version.
Which do you have?

check this link for the part number

Fullsize Page 10 of Bicycle Lamps 2009

This company sells replacement halogens

http://www.peterwhitecycles.com/b&m-hl.asp

 

[Orraman]

Kitchenman,

Late Again but I writ it, I'll post it.

It would appear from your photos and the link below that your light has a halogen main bulb and an LED stand light.
If this is so you could spin the wheel briskly and see if the stand light comes on when the wheel stops, this indicating voltage at the lamp.
If not check that the dynamo is producing AC voltage and that it is available at the lamp.
You could check for continuity between the wires entering the light, indicating a good bulb or a short.
Some halogen bulbs are sensitive to fingerprint grease, test for continuity.
If bulb is good test for dynamo AC at bulb contacts.
If not check one contact at the lamp to the opposite contact at the dynamo for voltage to isolate each wire.
Failing that.
Contact me for a low offer and a good home, remembering that I offered three half crowns and a good home and got a fine wife.

Slow Dissleccik Dave

Front Lights for Schmidt Hub Generators

 

[kitchenman]

Apparently they do two types, a diode version or a halogen bulb version.
Which do you have?

check this link for the part number

Fullsize Page 10 of Bicycle Lamps 2009

This company sells replacement halogens

Busch & Muller dynamo bicycle lights

Thanks. I have the halogen version ...

 

[kitchenman]

Kitchenman,

Late Again but I writ it, I'll post it.

It would appear from your photos and the link below that your light has a halogen main bulb and an LED stand light.
If this is so you could spin the wheel briskly and see if the stand light comes on when the wheel stops, this indicating voltage at the lamp.
If not check that the dynamo is producing AC voltage and that it is available at the lamp.
You could check for continuity between the wires entering the light, indicating a good bulb or a short.
Some halogen bulbs are sensitive to fingerprint grease, test for continuity.
If bulb is good test for dynamo AC at bulb contacts.
If not check one contact at the lamp to the opposite contact at the dynamo for voltage to isolate each wire.
Failing that.
Contact me for a low offer and a good home, remembering that I offered three half crowns and a good home and got a fine wife.

Slow Dissleccik Dave

Front Lights for Schmidt Hub Generators

I've started testing from scratch. Trying to get a spark by putting a coin or key between the terminals of the hub. No spark! ..... or its so small I can't see it or I just can;t see sparks! .....
If I want to my Fluke 79 meter to test if the hub is producing a voltage do you know which setting I need to use? ... Symbols are OFF, V(with wavey line), Hz, V(wavey line and dotted line), mV(wavey line and dotted line) and Ohms ... and ...five vertical lines labelled 40 Ohmns and an A with a straight and dotted line on top ...

 

[shemozzle999]

V wavey line - you can connect the two leads anyway around it does not matter - I think you should see a reading of 6 volts.

 

[kitchenman]

Ok.. In that test it did generate a voltage. The meter is reading an average of about 092.0 mv ac .... which I'm guessing is about 1 Volt? ....

 

[kitchenman]

umm ... just did the same test again and now and am getting between 05.00 and 07.00 v a c which sounds more like it! ..
I broke into the cable at the hub end and connected the light and it works ! ... Main light AND LED! .. cool ....

 

[shemozzle999]

Good news. The wiring or connectors need closer inspection then to see where it is breaking down.

 

[kitchenman]

Good news. The wiring or connectors need closer inspection then to see where it is breaking down.

yes. Continuity test failed. The cable goes into my frame which is a pain to access so I think I'll wire it where I can see it for now and do the proper job next time I need to get inside.
Thanks to all

 

[shemozzle999]

Respect to you for attempting to fix it yourself.
Now all you need to do is to work out why it failed and ensure you allow for that in the fixing process.

 

[kitchenman]

Decided to do the proper job! .. Not that difficult to get inside the frame. Found the problem which I now remember! I simply had not connected the cables due to a broken plastic connector which I was going to replace but never did! ... by=passed it and all working as it should be now! .. thats made my Christmas! ..