Sorry to be a pain with this, but my dynamo is losing its residual magnetism.
I have cleaned it, flashed it, replaced the voltage regulator (from a K-tec solid state regulator to a new DVR2; 6v positive earth (my bike has always run positive earth)).
I can flash it and it works fine. Stop the bike, check the dynamo and it has stopped generating any voltage.
I have wired up the DVR2 correctly. Fitted a 10 amp fuse, which hasn't blown. I have flashed dynamos before (for positive and negative earth bikes). I have fitted voltage regulators before (positive earth and negative earth regulators).
The reason for changing the voltage regulator was that I thought it was the problem.
I am at a total loss as what to try next!
I am soon to start beating the bike with a very large stick as it is really taking the p@ss!
ps Some of the wires to and from the ammeter do look old. I am a bit loathed to replace them as they are the nice old rubber coated ones.
Is the dynamo casing the original iron one? Some have been made aftermarket from stainless steel and they will not retain their magnetism very well. Also check the big screw in the casing is nice and tight.
If I spray the bushes and armature with electrical cleaner, it will start charging again.
!
I would say you have found the problem! Obviously there should be good conductivity between brushes and commutator.
Have you cut back the insulation between the commutator segments by about 1/32 of an inch, with a hacksaw blade? The copper commutator wears and the insulation can hold the brushes proud breaking the connection.
