Faulty Stator perhaps?
Re: Faulty Stator perhaps?
Thank you gentlemen for your input.
So, with the parts on the bench, including the battery of course, I have 12 volts from the stator to the regulator. If the regulator passes this straight through, as it appears to be doing, this would seem to indicate a faulty regulator from what you say.
On the other hand, it is a brand new AO regulator which passes all the diode checks done on it.
There have been no comments on my suggestion about the stator only being connected to the battery after the key is ON and taking the regulator output straight back to the battery. Is that because it is too idiotic to consider and, if so, why?
Anybody got a good working Morini regulator they would be prepared to lend me to check things out?
So, with the parts on the bench, including the battery of course, I have 12 volts from the stator to the regulator. If the regulator passes this straight through, as it appears to be doing, this would seem to indicate a faulty regulator from what you say.
On the other hand, it is a brand new AO regulator which passes all the diode checks done on it.
There have been no comments on my suggestion about the stator only being connected to the battery after the key is ON and taking the regulator output straight back to the battery. Is that because it is too idiotic to consider and, if so, why?
Anybody got a good working Morini regulator they would be prepared to lend me to check things out?
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Re: Faulty Stator perhaps?
An Al Osbourne regulator? They are for dynamo systems only, your bike has an alternator. I'll take look at AO website to see if they do what you need, which is s rectififer/regulator.
EDIT! OK ignore what I said above-AO do the right thing nowadays so panic over. (My panic that is)
EDIT! OK ignore what I said above-AO do the right thing nowadays so panic over. (My panic that is)

All donations to the rest home for old Camels, Leicestershire.
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Re: Faulty Stator perhaps?
The other option being that the diodes are back to front and passing current through to the regulator! However, I do not have a wiring diagram for the rectifier and no idea how it works. There may be one on the nederland club pages accessible from this site.velojames wrote: ↑13 Oct 2025 09:21 Thank you gentlemen for your input.
So, with the parts on the bench, including the battery of course, I have 12 volts from the stator to the regulator. If the regulator passes this straight through, as it appears to be doing, this would seem to indicate a faulty regulator from what you say.
On the other hand, it is a brand new AO regulator which passes all the diode checks done on it.
There have been no comments on my suggestion about the stator only being connected to the battery after the key is ON and taking the regulator output straight back to the battery. Is that because it is too idiotic to consider and, if so, why?
Anybody got a good working Morini regulator they would be prepared to lend me to check things out?
All I know is how mine operates.
Edit:
Is this the one? http://www.aoservices.co.uk/products/a-reg.html
Re: Faulty Stator perhaps?
I believe with the standard reg. rect. the stator windings are live all the time even with the engine not running and the key out. Some people used to introduce fuses in case of faults.
Donkey's years ago I did sit outside a pub with some other MRC members and watch as my bike stated to smoke from the air ducts around the stator and later found that it was the dodgy old stator I had fitted, which decided to short to "earth" as we sat in the beer garden admiring the Morinis. The stator cooked itself and I had to fit a better one, no problems ever with that one. My point though; As it was live all the time it was possible for it to do what it did.
Donkey's years ago I did sit outside a pub with some other MRC members and watch as my bike stated to smoke from the air ducts around the stator and later found that it was the dodgy old stator I had fitted, which decided to short to "earth" as we sat in the beer garden admiring the Morinis. The stator cooked itself and I had to fit a better one, no problems ever with that one. My point though; As it was live all the time it was possible for it to do what it did.
Re: Faulty Stator perhaps?
Thanks Bumblebee,
That must have been a moment of panic I daresay.
It seems that it has been firmly established that the stator is always live and that 12 volts appears on both yellow leads whether the bike is switched on or not. Now, my new and double checked regulator is passing this straight through. Do original Morini regulators (Ducati?) not do this? Now I am not sure if my regulator is OK or not.
Anyway, thanks to everyone who has sent advice. I will have do do more thinking.
That must have been a moment of panic I daresay.
It seems that it has been firmly established that the stator is always live and that 12 volts appears on both yellow leads whether the bike is switched on or not. Now, my new and double checked regulator is passing this straight through. Do original Morini regulators (Ducati?) not do this? Now I am not sure if my regulator is OK or not.
Anyway, thanks to everyone who has sent advice. I will have do do more thinking.
Re: Faulty Stator perhaps?
Missed the additional query from Mickey about the make of reg. Yes that is the one. I believe I mentioned earlier that the wiring is Not according to the incomprehensible Morini diagram but to one of Rupert Paul's diagrams.
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Re: Faulty Stator perhaps?
Electric Start models have an in line fuse. The battery is connected to the starter solenoid and is teed via a fuse to the fuse box and teed to the ignition switch and alternator. Yes, the windings are live all the time, bear in mind before removing the stator. Don't ask me how I knowBumbleBee wrote: ↑13 Oct 2025 12:25 I believe with the standard reg. rect. the stator windings are live all the time even with the engine not running and the key out. Some people used to introduce fuses in case of faults.
Donkey's years ago I did sit outside a pub with some other MRC members and watch as my bike stated to smoke from the air ducts around the stator and later found that it was the dodgy old stator I had fitted, which decided to short to "earth" as we sat in the beer garden admiring the Morinis. The stator cooked itself and I had to fit a better one, no problems ever with that one. My point though; As it was live all the time it was possible for it to do what it did.
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Re: Faulty Stator perhaps?
The Morini diagram is quite simple. Just need a magnifying glass!
Re: Faulty Stator perhaps?
With the standard system; When the ignition is off and the engine isn't running the voltage from the battery comes through the standard reg. rect. and imposes itself onto the stator (Yellows and Red). It doesn't reach the part of the stator thats for the ignition (Green and "Earth") that is a totally separate system that runs on much lower voltages and would be damaged by battery voltage.
Re: Faulty Stator perhaps?
I didn't quite understand that. In my system the stator red lead is connected directly to the battery. From the stator the yellow leads take the 12 volts on to the reg. rect. and the latter then passes that straight on to the ignition circuit - hence it is permanently live. So it would seem that I have two components which are thought to be OK but which are not behaving as expected
I am thinking that I may just have to try fixing it so the stator is not live until the ignition is switched on and then connecting the reg. rect. output straight to the battery, start up and see what happens. If I see smoke, disconnect quickly!
Your inputs much appreciated.
I am thinking that I may just have to try fixing it so the stator is not live until the ignition is switched on and then connecting the reg. rect. output straight to the battery, start up and see what happens. If I see smoke, disconnect quickly!
Your inputs much appreciated.
Re: Faulty Stator perhaps?
Yes on the standard system Red is where the positive current will appear. Yellows are where negative currents will appear. The flow of those currents around the circuit Red > Battery positive > Battery negative > Reg.rect. > Yellow and back through the stator to Red where it began is controlled by the reg. rect. being in circuit.
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Re: Faulty Stator perhaps?
I think as the AO component is made for old British iron then you may have an incorrect unit for the Morini.
http://www.aoservices.co.uk/info.html
On the above link click on the link to Alternator regulator A-reg there is a diagram. Firstly, it is wired positive earth, whereas the Morini is negative earth. This not a problem, just reverse the red and black.
If there is a bridge rectifier then the output from the alternator wires will pass to the regulator when the engine is running. This is the AC to DC conversion. However the Morini has a DC component on the alternator wires from the red lead from the battery. (Looking at the diagram on the AO site, there appears to be no connection to the battery on the old iron). The rectifier will pass this through even with the engine not running. Open the link
http://www.aoservices.co.uk/products/rectifier.html
to see a basic bridge rectifier. However, as I have said before, I do not have a diagram for the Morini reg rec so do not know what goes on inside it.
If I was you I would telephone AO and tell them you have bought their unit for a Morini and it has 12 volts DC on the alternator coils and see what they say. You also appear to have non standard wiring, so without a diagram it is hard to see what is going on.
As per Dragons' Den, I'm out.
http://www.aoservices.co.uk/info.html
On the above link click on the link to Alternator regulator A-reg there is a diagram. Firstly, it is wired positive earth, whereas the Morini is negative earth. This not a problem, just reverse the red and black.
If there is a bridge rectifier then the output from the alternator wires will pass to the regulator when the engine is running. This is the AC to DC conversion. However the Morini has a DC component on the alternator wires from the red lead from the battery. (Looking at the diagram on the AO site, there appears to be no connection to the battery on the old iron). The rectifier will pass this through even with the engine not running. Open the link
http://www.aoservices.co.uk/products/rectifier.html
to see a basic bridge rectifier. However, as I have said before, I do not have a diagram for the Morini reg rec so do not know what goes on inside it.
If I was you I would telephone AO and tell them you have bought their unit for a Morini and it has 12 volts DC on the alternator coils and see what they say. You also appear to have non standard wiring, so without a diagram it is hard to see what is going on.
As per Dragons' Den, I'm out.
Re: Faulty Stator perhaps?
Thank you very much Mickey and Bumblebee. I shall study what you say and try to inwardly digest it all. The root of the problem may be that it is an unsuitable reg. rect. as you say and I shall follow it up, though I think it may have been Rupert Paul himself who suggested that one, not sure.
Probably best to call time on this line now.
Probably best to call time on this line now.
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Re: Faulty Stator perhaps?
Keep us posted, please.
Others can learn from people's experiences.
Others can learn from people's experiences.
Re: Faulty Stator perhaps?
OK, will do, but don't hold your breath.
Thanks again everyone.
James
Thanks again everyone.
James