T3 charging issue

[Perazzimx14]

Generator light still on at all RPM's

Battery 12.63v static
Battery 12+ volts when motor running does not rise with higher RPM's
Alternator across the slip rings 3.5 ohms (rotor pulled to test)
New diode board with confirmed good grounds to the frame
All wires from alternator to diode board confirmed continuity
New headlight bucket wiring harness (all lights work as the should)
Generator light goes out if unplugged from regulator as it should


Is there a way to test the solid state regulator??

Any other ideas

[Two Checks]

Make sure the brushes are making contact.

[canuck750]

I went through two brand new voltage regulators getting my V7 Sport to charge and eventually installed the original one, issue solved immediately. I spent many hours chasing my tail as every single electrical part was brand new but I could not get a charge.

[Perazzimx14]

Make sure the brushes are making contact.

Continuity test confirmed that also.

I went through two brand new voltage regulators getting my V7 Sport to charge and eventually installed the original one, issue solved immediately. I spent many hours chasing my tail as every single electrical part was brand new but I could not get a charge.

I am leaning towards the VR but hate to blindly replace. Can you test them??

[injundave]

I had a solid state regulator/rectifier fitted to my T3, made by Electrex World in England. When I had some trouble with it their tech guy sent me a troubleshooting guide. I don't know if it will help you but here it is. Incidentally, I had to replace the unit.

[radguzzi]

Check the ground wire connections...

[Kiwi_Roy]

Make sure you have 12 Volts at the regulator.
Pull the DF+ wire off the regulator and measure it to chassis confirming you have a good circuit through the rotor to chassis.
Good ground on the regulator.
If you touch the DF+ wire to +12V with the bike running you may be able to hear the alternator load up.
http://www.thisoldtractor.com/guzzi007/schematics/1974_850T_USA.gif
You never said what year
http://www.thisoldtractor.com/guzzi007/schematics/1980_T3_Europe.gif

You mention new wiring, my guess is somethings not quite right.

[Perazzimx14]

Make sure you have 12 Volts at the regulator.
Pull the DF+ wire off the regulator and measure it to chassis confirming you have a good circuit through the rotor to chassis.
Good ground on the regulator.
If you touch the DF+ wire to +12V with the bike running you may be able to hear the alternator load up.
http://www.thisoldtractor.com/guzzi007/schematics/1974_850T_USA.gif
You never said what year
http://www.thisoldtractor.com/guzzi007/schematics/1980_T3_Europe.gif

You mention new wiring, my guess is somethings not quite right.

76 T3. All stock wiring except for a new headlight bucket wiring harness. The rest of harness is amazingly unmolested and in good shape.

I will check the above this morning.

[Kiwi_Roy]

When you are looking at the two schematics I attached I believe the second one is more correct around the alternator, all of the alternators I have seen had one brush D- grounded at the plate.
The Y terminals of the rectifier and the alternator join together.
We all owe Carl a huge thanks for providing these schematics, every now and then a mistake slips through, more than likely because the factory schematic was wrong in the first place.

I think if you pull the DF wire the charge light should go out, the lamp current provides the initial current to the rotor to start it off, you haven't replaced the lamp with an LED by any chance?

This schematic while not of your bike shows a little more detail of the regulator, note how they don't rely on just the charge lamp but have an 80 Ohm resistor (45) in parallel with the lamp, you would need something similar for an LED
http://www.thisoldtractor.com/guzzi007/schematics/1977_SB_Police_Bosche_Motoplat.gif

[Perazzimx14]

Pulling the DF terminal does make the generator dash light go out. No LED's only stock incandescent.

[Kiwi_Roy]

From looking at the schematic it should go out, the lamp current passes through the regulator then through the rotor to chassis


Sent from my shoe phone!

[Perazzimx14]

Down to the voltage regulator. Ordered a new one this morning will report back in a few das after it arrives.

[Kiwi_Roy]

Pull the DF wire off at the regulator, measure the wire spade connector to chassis, I think it should be ~ 4-6 Ohms
(the 3.5 Ohms you measured in your first post + the 2 brushes)
Lift either brush and it should go open

Measure the yellow wires to chassis they should be open

You asked earlier about testing the regulator - in theory
If you substitute a lamp DF to ground for the rotor and connect the positive and ground to a power supply
At 12 Volts the light should be On, as you increase the Voltage at somewhere around 14 Volts the light should go out.
In liu of power supply you could substitute a battery and charger, as the battery charges up again the lamp should go out.

Bear in mind, I haven't actually tried this but I see no reason why it shouldn't work.
For a lamp I would use a tail of flasher lamp 2 - 4 Amps