Magdyno

[Greenfield]

Hi
I'm only getting around 0.5v from the dynamo on the B33. I've checked the field windings and it seems good at 3 ohm. I've checked the winding resistance which seems good at around 0.7 ohm. The dynamo is on the bench. Any thoughts on where to go next?

[Pete C]

I have often had problems with charging after bikes have stood for a while. Cleaning the commutator, ensuring the carbon brushes are free, and flashing, in case there is too little residual magnetism in the coil, has usually fixed the problem without having to take them apart.

[Greenfield]

Thanks Pete
Whilst it was off the bike I thought I'd give the dynamo a good clean before replacing it. I noticed that one of the brush wires was frayed at the terminal end, with only a few strands making good contact. I soldered the joint, reassembled the dynamo and thought I'd give it a spin before flashing. On a fast idle it was generating 8v+; but then the battery is a bit low.
So whether it was the cleaning or the improved brush contact that remedied the problem, or a combination of both, we'll never know, but its another thing ticked off on the way to getting it back on the road.