Airone (Astorino Dynamo)

[jca...@br2architecture.com]

When I 1st got my 49 Airone I asked Valenti to send me what I should replace regardless of appearances,  in addition to engine case bearings, seals and gaskets he sent me a solid state reg/rec unit for the Dynamo and bearings The solid state unit has five wires labeled 51 and 61 (that's easy to figure out they go to the terminals on the cap) the other three wires are marked 'C', 'SP' and '-'. The original regulator / rectifier has no markings on the screw terminals to identify C, SP or -.

I am assuming C and SP are the two wires coming from the field coil that is secured to the body of the dynamo (the zinc plated tube with the insulated coil screwed to it) and the negative would be the lug that is attached to the base of the reg / rectifier assembly.

First off have I described the wiring correctly?

Second, how to determine which is C and which is SP on the field coil (I am guessing that is what it is called).

[SED Sci]

SP goes to the armature, it is not a field wire.

Campo = field.  One of the field wires (C-) is grounded to the dynamo body next to the grounded brush.  The other field wire goes to the regulator - this is C+.  Connect it to C+ on the solid state reg.  I've seen a reference that the field wires are black and dark brown to indicate positive and negative (don't know which but could maybe find the reference for you), but an electrical engineer said polarity shouldn't matter and it's worked on the 2 I've done.  The insulation on the field leads was crumbling so jacketed them with shrink tubing.

SP - spazzola = brush. The SP wire attaches to the insulated brush.  Check to make sure the U-shaped bridge that crosses over the bearing housing (insulated brush and SP wires screw to it) is not grounded - it's just trapped under the cover screw.

The field, armature and reg all share a ground through the body of the dynamo.  Make sure you have good battery connections - if you lose the ground the dynamo over charges blows the bulbs and cooks the solid state reg and it smells like burnt fish for a week!  

[jca...@br2architecture.com]

Thank you Shawn, great explanation and bery helpful!

[steven s.]

How interesting that the electrical terms for "brush" and "field" are such literal translations in Italian! Good to know.

Steven S 

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[pouma1954]

No, they're literal translations in English. 

Paul 

Envoyé depuis mon appareil Galaxy

-------- Message d'origine --------

De : "'steven s.' via Guzzi Singles" <guzzi-...@googlegroups.com>

Date : 29/12/2020 07:40 (GMT+01:00)

À : guzzi-...@googlegroups.com

Objet : Re: [guzzi-singles] Re: Airone (Astorino Dynamo)

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[John O Regan]

Hi All,

Getting the field coil connections wrong will prevent the dynamo from working

To get a dynamo to work in the opposite direction you swop either the field coil connections or the brush connections (Not Both)

John

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[SED Sci]

Hi John, the field coil is just a loop of wire, does it really matter which way the electrons flow through it?  (or maybe I don't understand what you mean by connections)

[John O Regan]

Hi All,

When the field wires are reversed so is the polarity of the magnetic field created ,

When the field wires are reversed the dynamo will produce voltage if spun in the opposite direction

This is true for any Lucas and Miller dynamos for sure, and I cannot see that Marelli would be any different

It's been 40+ years ago since I studied electrical theory as part of my apprenticeship and I have forgotten a lot of it

but retained practical things that are needed for vintage motorcycle electrics and everyday power electrics

One of the jobs waiting for me on my GTW is to replace the regulator as it is burned to a crisp, I just hope the dynamo windings have survived

I am going to try a 12 volt conversion if the dynamo windings are OK as I have a couple of electronic regulators to hand

John

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[SED Sci]

That makes sense.  I did confirm that the the dynamo motored in the correct direction.  Maybe I got lucky twice!