I am looking for help that is not covered in the 205 messages about Dynamos in the forum which I have now read.
I have a E3L dynamo which being part of a basket case, I have stripped and rebuilt. As part of this I have measured the field coil at 3.2 ohms and each of the coils in the armature are showing around 3.5 ohms across the commutator. The commutator surface has been cleaned and polished with wet and dry (used dry) and the bakelite cut back. The brushes have been replaced and checked to ensure that the are seating properly. The earths and continuity through the coil and through the brushes are good. So at this point all looked good.
I then flashed the coil and then tested the dynamo by motoring it - all was good with it being smooth and turning clockwise as expected.
The next test was to try to generate a voltage so with F and D shorted I drove the unit from my drill - result no appreciable output (<0.5v) when driven clockwise or counter clockwise. While this tests method is mentioned in the threads, to my mind this method relies on there being some retained magnetic field in the field core to start to build the voltage in the armature that then goes onto build the voltage in the field and so a virtuous circle is created.
Assuming that the initial retained magnet field may not be present I then separated the F and D terminals and applied 12V to the field coil and drove the dynamo while monitoring the D terminal. Result 7v at the D output.
I had hoped that having now output decent voltages that I would now be able to repeat the generator test and get an output - no such luck again no appreciable output.
So where is the flaw in my thought process, and where do I need to look for a fault.