May 9, 2017

Necchi BU - NA Wiring

After a lengthy search I discovered that there were no simple wiring diagrams for the BU series.

Since the light is one of those 12v things from my 1972 Fiat Spider it requires the transformer to drop the 110v to 12v

Here are photos of both the Nora and the Miranda.

I removed the auxiliary cord from both

The light is chassis grounded so there is only one wire going to it


Based on the two machines I have for reference, use only if you have background and / or familiarity with electrical systems.

I removed the auxiliary outlet on both because the cord was deteriorated.


  1. Tom, thank you for this info. I was looking for the same info for 2 parts machines that need rewiring. This helps greatly.

    1. Glad it helped, I'm not an amateur but I found this wiring confusing, and after blowing a hole in one of those 12v lamps I decided trial and error was not going to be fruitful

  2. I understood the stepdown transformer, but didn't realize the "light" switch as actually an on/off switch, but makes sense. Since mine were also with mismatched motors, I was wondering if the transformer was enough to vary speed as I'm used to a motor with a different brush offset for a separate speed. Seems like the transformer is not an ideal way to vary motor speed. My early BU Nova didn't have that option. Many thanks, again.

    1. Yes I think that using a transformer to step down the top speed may be the cheapest and therefore the least desirable way they could have gone. A servo with a real variac would be nice. They didn't have cheap electronics back then!