Dynamo troubleshooting



njwilken

New Member
Jul 23, 2006
3
0
0
I am restoring an old bike with a generator lighting system - the kind that presses against the tire to spin the generator. The system doesn't work though I've replaced bulbs and all wiring. Do these things fail with some frequency and should I just replace it and/or ditch it? The lights are built into the front and rear fenders and rack, so it's a kind of groovy looking system and it would be fun to get it working.
 
Do you have each of the components earthed?
Run a piece of wire from the body of each light to the body of the dynamo to check if they work. ;)
 
"Grounded" is the term for "earthed" in the US. That is one possibility. Which is more inportant to you, keeping the bike authentic or making it a little more efficient? If grounding doesn't work, then the dynamo is probably bad. You can check the dynamo with a multimeter by attaching the positive lead to the output wire of the dynamo and touching the negative lead to the dynamo casing. You will need to have the bike on a bicycle stand to do the test as you will need to turn the pedals to get the wheel moving.

If the dynamo is bad, you can get a replacement fairly easily. If it were me though, I would replace the dynamo with a small battery pack. That way you get to still have the lights work but you don't get the drag of the dynamo when you are riding.