Horn kills the motor?

discussions specific to the 906 Paso
User avatar
JWilliam
Posts: 331
Joined: Wed Oct 06, 2004 12:00 am
model: 906 Paso
year: 1989
Location: Nottingham, UK

Re: Horn kills the motor?

Post by JWilliam »

OK, here is how it works and what to do if you have purchased an aftermarket Rectifier with no charge warning light circuit. The two yellow wires enter the Rec/Reg and the AC voltage is converted by a full-wave rectifier. Once rectified this represents the 12v DC system. You can still use a three-phase rectifier; only use two of the power inputs. The Red wire is connected to the alternator winding and does supply an AC voltage but it is a signal wire, not a power wire!
To utilise the charge warning light, connect the blue wire to the red wire using a series '1N 4004' diode, with the blue wire being the positive voltage source. When the engine is stopped, a very low leakage current will flow from the charge warning light, thru the windings and thru the Rec/Reg diodes - it is a very low value but enough to illuminate the warning light. When the motor is started the red wire will emit a voltage. The Red wires AC voltage opposes the 12v DC feed thru the charge warning light and the light goes out! The DC circuit is protected by the 1N4004 diode.
Attachments
tmp_27131-Charge%20light-865223396_zpsnzx56sqe.jpg
tmp_27131-Charge%20light-865223396_zpsnzx56sqe.jpg (57.89 KiB) Viewed 9768 times
User avatar
Derek
paso grand pooh-bah
Posts: 768
Joined: Thu Nov 03, 2011 10:13 am
model: 907 I.E.
year: 1994
Location: Scotland

Re: Horn kills the motor?

Post by Derek »

Mc tool wrote:Yeah ( Derek :) ) if the red wire wasn't connected to earth ...... but it is and I reckon if that scr shorted it would take 1/2 a nanosecond for something to blow , if your lucky :?: you might see the flash reflecting off the workshop walls and a mushroom cloud making its way across the ceiling but you'd have to be quick :D
Agreed Hamish, but I'm assuming the OP must have disconnected the rewire to measure between it and ground and it may not be the SCR that is short circuit but some other component in the regulator that provides a high resistance path. This would show +12V on a digital MM but with very little current available. Anyway, it's just conjecture.
1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


Scotland
User avatar
Derek
paso grand pooh-bah
Posts: 768
Joined: Thu Nov 03, 2011 10:13 am
model: 907 I.E.
year: 1994
Location: Scotland

Re: Horn kills the motor?

Post by Derek »

JWilliam wrote:OK, here is how it works and what to do if you have purchased an aftermarket Rectifier with no charge warning light circuit. The two yellow wires enter the Rec/Reg and the AC voltage is converted by a full-wave rectifier. Once rectified this represents the 12v DC system. You can still use a three-phase rectifier; only use two of the power inputs. The Red wire is connected to the alternator winding and does supply an AC voltage but it is a signal wire, not a power wire!
To utilise the charge warning light, connect the blue wire to the red wire using a series '1N 4004' diode, with the blue wire being the positive voltage source. When the engine is stopped, a very low leakage current will flow from the charge warning light, thru the windings and thru the Rec/Reg diodes - it is a very low value but enough to illuminate the warning light. When the motor is started the red wire will emit a voltage. The Red wires AC voltage opposes the 12v DC feed thru the charge warning light and the light goes out! The DC circuit is protected by the 1N4004 diode.

Image
I can see how that will work but it's NOT the arrangement of the original wiring and regulator in which the red wire is not the for the charge light and the regulator has an output terminal dedicated to it.
1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


Scotland
User avatar
JWilliam
Posts: 331
Joined: Wed Oct 06, 2004 12:00 am
model: 906 Paso
year: 1989
Location: Nottingham, UK

Re: Horn kills the motor?

Post by JWilliam »

Derek wrote: I can see how that will work but it's NOT the arrangement of the original wiring and regulator in which the red wire is not the for the charge light and the regulator has an output terminal dedicated to it.
Well it works for me my friend, the battery is charged and I have my warning light back. I know how the original wiring is and that the Energis Rectifier is a do-it-all unit. As for the Red wire not being for the charge light - how do you know its not for the charge light?
The aftermarket Rec/Reg unit on my Paso has no terminal for a charge warning light, its a 2 phase Alternator - meaning two power wires. No matter where the red wire is placed in the windings, it will produce an AC voltage so what else could it be for? Rectifying the Red wire causes a hot terminal, so using it for a milli-amp bulb is going to stop that. Even if this is all wrong, it solves a lot of problems and doesn't create any others.

Look Derek, we all want you to have a smokin' Paso, just not literally OK?
User avatar
Derek
paso grand pooh-bah
Posts: 768
Joined: Thu Nov 03, 2011 10:13 am
model: 907 I.E.
year: 1994
Location: Scotland

Re: Horn kills the motor?

Post by Derek »

Well, let's not argue about it, and it is good to see that you have come up with a circuit that maintains the charge light using a regulator that has no provision for one.
And incidentally a 2 wire alternator is single phase.
1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


Scotland
User avatar
JWilliam
Posts: 331
Joined: Wed Oct 06, 2004 12:00 am
model: 906 Paso
year: 1989
Location: Nottingham, UK

Re: Horn kills the motor?

Post by JWilliam »

One look at two and three phase Alternator diagrams will produce many variants. Three wire 3 phase alternators are available, for instance. This Ducati Alternator is a 2 phase with centre-tap and yes, it appears the tap can be connected to 12v as this next link shows (wiring diagram from a 750GT at bottom of page). Not sure if I'd want to do it what with melting plastic on a terminal when I have sent it thru the rectifier (same thing). So all told its difficult to know if I'm doing entirely the right thing. However, with only the pink wires to the rectifier, it is charging...
http://willyg.homelinux.net/Alternator/
Having a read of this article it would seem that if the two pinks are rectified and the red goes to 12v then high load charging (ie all lights on) is good but low rpm charging poor. If only the two pink leads are sent to the rectifier and the red wire centre tap disconnected (or used for a charge warning circuit) then low rpm charging is better but high load charging is worse. But no harm done.
User avatar
paso750
paso grand pooh-bah
Posts: 5558
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Horn kills the motor?

Post by paso750 »

the center tab is an exit for the positive halfwave. Being positive it doesn`t have to be rectified just voltage regulated as is shown in Dereks picture. The alternator will work also if the center tab isn`t connected or used for something "different" but that will impact the efficiency (curve) of the alternator meaning it won`t reach its full power output potential. At least this is my understanding.

What seems wrong to me is that in Dereks design the center tab connects to negative. That can`t be right.

Have a look at p. 173-179. It`s for the old Duc 860 GT
http://www.ducatimeccanica.com/860_work ... age173.htm

just noticed you had edited your last post :banghead: :thumbup:
nickta
Posts: 295
Joined: Tue Jul 24, 2012 8:54 am
model: 907 I.E.
year: 1992
Location: Cairns, Queensland, Australia

Re: Horn kills the motor?

Post by nickta »

Hi G.

By connecting the 0 volt line to the centre tap gives effectively a 2 phase alternator. So either end of the "coil" will be 180 Deg apart. So when one end is peaking positive, the other end will be peaking negative. This can then be rectified with only 2 diodes to get what is a full wave rectifier, rather than 4 diodes without the centre tap.

It's all about forward biasing diodes and sine waves.

Cheers.

Nick.
FasYankee
Posts: 28
Joined: Fri Jun 12, 2015 8:21 pm
model: 906 Paso
year: 1990
Location: USA

Re: Horn kills the motor?

Post by FasYankee »

Ok so now I've checked with two multimeters just to be sure and it seems that the stator/alternator/whatever it's called is toast, across the two yellows (mine as light tan actually) it only reads 5.Xv AC. The battery stays at a constant 12v, no change any rpm.

So where to source a new one? The reg/rectifier seems to be a bunch on eBay, might as well just replace that too while I'm at it.
Mc tool
paso grand pooh-bah
Posts: 1874
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: Newzealand

Re: Horn kills the motor?

Post by Mc tool »

My bike has the red wire going to the (Honda )reg/rect as a phase and it all seems to work ok . I also have a bosch alt with a similar set up on my Guzzi and the manual for that sez that the efficiency of the alt is improved by treating this "center tap "( I don't think that's the correct term in this instance ) as a phase and hooking it up to a 3 ph reg/rect :)
I wish I was young again............Id be heaps smarter than last time
User avatar
higgy
paso grand pooh-bah
Posts: 3327
Joined: Tue Jul 29, 2008 9:50 pm
model: 907 I.E.
year: 1992
Location: Hilltown,Pennsylvania
Contact:

Re: Horn kills the motor?

Post by higgy »

My personal recommendation is to have it rewound as a single phase Stator by these guys, it will be cheaper and newer than buying a new single phase regulator and he will give you a one year guaranty. Can't beat that with a very large stick :thumbup: Shoot them an email and they can give you a current price and turn around time, they are very helpful and responsive BTW there are many reasons why not to use the 3 wire(two Phase stator)
But I am not looking to start another argument. Suffice it to say the single phase will give you more watts for whatever you need over the 3 wire type

http://ricksmotorsportelectrics.com/

Make sure you ask them to put at least 5 foot lead wires on so you can wire directly to a decent regulator like one from this guy

http://roadstercycle.com/

Did this to my 907 with dual headlights( and all the suggested wiring updates and a few of my own) and have solved my issues permanently


I did the FH020AA regulator but I would suggest you go with one of the more modern SH847 which is a true regulator and not a shunt which will insure a long life for your rebuilt stator
Last edited by higgy on Thu Jul 21, 2016 2:05 pm, edited 1 time in total.
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
User avatar
Derek
paso grand pooh-bah
Posts: 768
Joined: Thu Nov 03, 2011 10:13 am
model: 907 I.E.
year: 1994
Location: Scotland

Re: Horn kills the motor?

Post by Derek »

paso750 wrote: What seems wrong to me is that in Dereks design the center tab connects to negative. That can`t be right.
Yes, the centre tap is to the -ve but the other two are to the +ve and the SCRs are reversed so it will still work.
This has been a very interesting and educational thread. I'm glad though that both my 907 and my Pantah have 2 wire alternators ;)
1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


Scotland
User avatar
paso750
paso grand pooh-bah
Posts: 5558
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Horn kills the motor?

Post by paso750 »

So where to source a new one? The reg/rectifier seems to be a bunch on eBay, might as well just replace that too while I'm at it.
http://www.electrosport.com/street-bike ... pt=stators
if you want to get another reg/rect too don`t buy an original one.
FasYankee
Posts: 28
Joined: Fri Jun 12, 2015 8:21 pm
model: 906 Paso
year: 1990
Location: USA

Re: Horn kills the motor?

Post by FasYankee »

Yeah, so between the kids sports, me doing massive amounts of overtime, my project bike & never ending honey-do list I decided to pass the work off to Seacoast in NH. $50 picked the bike up in CT, transported it to their shop via their sprinter van. They're doing a top to bottom overhaul/refresh. Bike should be tip-top when I get it back in time for spring. (Actually it'll probably be done next week).
Post Reply