Lario charging issue (with FIX)

[kevdog3019]

Pete mentioned something about "flashing" the stator. Could you elaborate on that Pete? Also... the stator and rotor were separated about 5 days.
Chuck, yours seems to be missing that spade by your last pic. Here's mine

[dan_s]

Guzziology mentions passing 12v briefly through the rotor sliprings in alternators that were unused a long time. That?

[Kiwi_Roy]

I may be wrong but check the length of your brushes, anything less than 1/2" should be replaced.

The wire goes to the DF brush terminal (non grounded one)

Make sure if you pull the wire off that the charge light goes out.

[kevdog3019]

Prey tell how I pass 12 volts through the rotor?  Lick the battery terminals and touch the rotor?  :BEER:

[Vasco DG]

Kev, in theory a field excited system like the Bosch AT&T shouldn't need polarising, it's something that should only be relevant to DC generators BUT for some reason, especially on bikes that have sat idle for a long time or the rotor has been swapped out the residual magnetism in the pole is insufficient to create the required magnetic field when trickled with the initial voltage through the brush to the front slip ring.

Quite simply you can 'Flash' the system to give it a direct feed and it will sometimes jump to life. Don't ask me for any more explanation than that, I just know it works, sometimes......

Remove alternator cover and start engine. Get someone else to hold the throttle at about 3,000rpm, (Or use the lock screw on the twistgrip if your bike has one.). Then just take a length of insulated wire. Hold one end on the battery positive terminal and briefly touch the other to the spinning front slip ring of the alternator rotor a couple of times. There will be Sparks and make sure the wire doesn't touch the hot exhaust and short out.

No guarantee it will help but it's worth a try.

Another thing is not all Bosch rotors are created equal. If you have one off a later BMW airhead by mistake the rotor will be a smaller diameter than those used on Guzzi's and earlier BMW's that used the Bosch system. This creates a wider air gap in the alternator and they will never charge adequately.

Pete

[kevdog3019]

Now if someone can tell me which is + and which is negative on the stator.  ???  

[guzzisteve]

One brush wire will be black that one's neg

[kevdog3019]

Ok Pete, good explanation thanks.  ;-T
By slip ring I suspect that's the rotor shaft (copper) the brushes are on?
Thanks much.

[LaMojo]

Back before the mid '60, cars had generators with mechanical regulators. Sometimes the old ones would need re-polorized if the points in the regulator would stick or the generator was dropped while repairing. Usually you could just take the cover off of the regulator and push down on the contact that connected the battery to the regulator for a second. This would "reboot" the generator. 

I have yet had to flash a 3P alternator even those that have set up for years. No need to. The modern regulator will supply start  up voltage to the rotor coil and regulate the output by varying the current which varies the electromagnetism within the rotor coils.

I'd look elsewhere for your charging problems.

[dan_s]

The plus end of the rotor (DF, front ring) connects to the regulator (purple wire usually) on the Bosch system. you can disconnect the regulator for a couple of seconds and do "the flash" by connecting the DF end in the connector to the battery plus, just for a fraction of a second. That you can do with one hand.

[Kiwi_Roy]

Now if someone can tell me which is + and which is negative on the stator.  ???  

The stator doesn't have polarity, it's a 3 phase AC winding

The rotor has polarity, one brush is grounded that's  Negative
The Ungrounded brush is Positive

Have you checked any of my suggestions in post #3?

One brush wire will be black that one's neg

There is no black wire in this case, it shouldn't be required if the regulator is well grounded.

Kev, check the regulator ground or provide a black wire.

http://www.thisoldtractor.com/guzzi007/schematics/1985_Imola_II-Monza-Lario.gif
It's not shown here but sometimes there's a black wire between regulator and alternator brush.

[kevdog3019]

I may be wrong but check the length of your brushes, anything less than 1/2" should be replaced.

The wire goes to the DF brush terminal (non grounded one)

Make sure if you pull the wire off that the charge light goes out.

Not much time over the holiday with the bike.  I did pull the wire and (without running) the light stayed on.  I have to hook the tank back in to run her and imagine this is what's necessary to check this.

[Kiwi_Roy]

Not much time over the holiday with the bike.  I did pull the wire and (without running) the light stayed on.  I have to hook the tank back in to run her and imagine this is what's necessary to check this.

I meant to ask before, you don't have an LED light do you, they don't draw enough current, they need something like an 80 Ohm resistor in parallel.

Some of the Guzzi schematics (Carl's 1986 V-65 Florida for example) show the workings of the regulator. I assume yours is the later electronic type, not the old mechanical one.

The bulb current is supposed to go to ground through the rotor, that's what creates the initial magnetic field to set the alternator in motion, once it starts to generate some Voltage there are 3 small diodes in the rectifier that feed the alternator voltage back to the regulator, this Voltage brings the terminal up to 12+ Volts so now the charge lamp has 12 Volts on both sides so it goes out.

Assuming you have an incandescent lamp I believe it should go out when you pull the wire off the brush, that's where the current goes to ground.
An LED draws so little current it can light on just the drain through the regulator bias resistors.
Try disconnecting the same wire at the regulator end just in case there's a short somewhere.
Lift the brush in the holder where the wire attaches, with your ohmmeter make sure it's not shorted to chassis, the wire goes on the brush that's insulated.



BTW, what year Lario?

[kevdog3019]

Well... It's working now thanks to all you good folks.  ;-T

I flashed the rotor by disconnecting the positive brush spade and sending a positive feed off the battery through it (brief sparks). Started her up and she's working as it should.  I would have never thought to do this if it wasn't for the good community here.  Thanks for your time with this "mystery" issue.

I do have LED lights.  The bike is an '87 I believe.  It has the updated tranny fill level hole set at 900ml. :'(  My '86 doesn't.
-Kevin

[Chuck in Indiana]

Well... It's working now thanks to all you good folks.  ;-T

I flashed the rotor by disconnecting the positive brush spade and sending a positive feed off the battery through it (brief sparks). Started her up and she's working as it should.  I would have never thought to do this if it wasn't for the good community here.  Thanks for your time with this "mystery" issue.

I do have LED lights.  The bike is an '87 I believe.  It has the updated tranny fill level hole set at 900ml. :'(  My '86 doesn't.
-Kevin

Good deal.  ;-T I flashed my 1000SP one time when all else failed. Why does it need to be done? No clue. Flash a generator? Absolutely. an alternator? Not normally, as far as I know.  ;D
I just put my 87 on the side stand and fill er up. Still have a fair amount of whine in fifth, though. Wonder how much whine is normal?

[Kiwi_Roy]

Well... It's working now thanks to all you good folks.  ;-T

I flashed the rotor by disconnecting the positive brush spade and sending a positive feed off the battery through it (brief sparks). Started her up and she's working as it should.  I would have never thought to do this if it wasn't for the good community here.  Thanks for your time with this "mystery" issue.

I do have LED lights.  The bike is an '87 I believe.  It has the updated tranny fill level hole set at 900ml. :'(  My '86 doesn't.
-Kevin

I don't recall having to flash an alternator but after all that's what the charge light is doing, think of it as a mini flash it's well documented that if the lamp burns out they won't start.
Incandescent lamps have another distinct advantage over LEDs, when they are cold the resistance is quite low the inrush when you turn the key on will be like a high current spike.

Your Lario didn't come with LEDs Shirley

[Chuck in Indiana]

Nope, Shirley they didn't..  ;D

[Kiwi_Roy]

Wire a 220 Ohm 1/2 Watt resistor in parallel with the LED, that will boost the current up by 50 milliamps may be enough to fix it.

[kevdog3019]

Wire a couple a 220 Ohm 1/2 Watt resistors in parallel with the LED, that will boost the current up by 50 milliamps may be enough to fix it.

What's to be fixed with my LED's?  They work no differently than the stock "old school" lights.  Stay on when the charging system is bad and go off when the charging system is good.  Perfect.  ;-T 

Yep... I fill on the sidestand Chuck.  Tie something from the front wheel to the sidestand. 

[Chuck in Indiana]

What's to be fixed with my LED's?  They work no differently than the stock "old school" lights.  Stay on when the charging system is bad and go off when the charging system is good.  Perfect.   

I think you should pay attention to what Kiwi Roy is saying. He's already told you why.. <shrug> the charge light is more than just something that lights up.  ;D

[Vasco DG]

I know the idea of flashing a field excited alternator is kooky but believe me, with the Bosch system, sometimes you have to. If the *light* is an LED the system won't work for the reason Roy stated. Add a resistor in parallel.

Pete

[kevdog3019]

I think you should pay attention to what Kiwi Roy is saying. He's already told you why.. <shrug> the charge light is more than just something that lights up.  ;D

I didn't understand what he was saying is all; now I do. It's a good idea for sure. In the year I ran it befor separation of the parts (recently) it never let me down. Being the electrical deficient person I am, I will have to have someone take me through this to get it right. What was said is a foreign language at best to me. I get the concept and agree but the fix...