Dynamo Output Help

[mickeytwonames]

Hello - asking for advice here

The dynamo on my Consort seems to only be outputting 1.5 volts
It spins as an electric motor when free of the fan belt
But when measured to Earth over the connected F and D terminals - outputs a consistent low voltage.
I have polarised it.

About to take it out and give it the once over (brushes look good)
Any comments re, bear traps, stupidities most welcome
MCP

[mickeytwonames]

Have taken Dynamo out and given it a 'talking to' - it now generates variable voltage output.
My problem of not charging not over but issues getting isolated.

[Garyhbates]

Hi Mike,
The Dynamo will output a variable voltage proportional to its speed, so it’s normal for it to be variable . I think mine produces 20 or so volts clean when it’s running fast. The regulator will regulate this higher voltage to a voltage that will be satisfactory to charge the battery and supply a stable 14volts for all the electrical items in the car . When the engine is running fast you should hear and feel the regulator working . It’s just a relay that switches the voltage on and off very fast . The higher the incoming voltage , the long it stays off to reduce the voltage .likewise when the Dynamo voltage drops the contacts stay closed for more of the time .
So listen for a buzz around that box . The most likely reason for it not regulating is that the tiny carbon contacts need a clean .
There is a small adjustment screw to adjust the output voltage.

[qantasqf1]

The dynamo has 3 connections: F, D and the casing is earthed. The regulator contacts open and close at a rate of about 30 times a second, although that varies with the state of battery charge and the demand placed on it by lights, heater and so on. When the regulator points are closed the D and F terminals connect and dynamo output rises. At about 13.5 volts output the points open and automatically insert a resistance between the 2 terminals and dynamo output drops to about 3 volts, and the sequence repeats itself. These Lucas cutout/regulators are very reliable and the only maintenance they need it to keep the 2 sets of contact points clean with very fine emery paper.

[qantasqf1]

...as I was saying, the dynamo has 3 connections: F, D and the casing is earthed. The regulator contacts open and close at a rate of about 30 times a second, although that varies with the state of battery charge and the demand placed on it by lights, heater and so on. When the regulator points are closed the D and F terminals connect and dynamo output rises. At about 13.5 volts output the points open and automatically insert a resistance between the 2 terminals and dynamo output drops to about 3 volts, and the sequence repeats itself. These Lucas cutout/regulators are very reliable and the only maintenance they need it to keep the 2 sets of contact points clean with very fine emery paper. As far as the dynamo is concerned your test is right. If you connect 12 volts across the D and F terminals it will rotate at a low speed. If you connect F and D together and run 12 volts to the jumper lead and earth it will rotate much faster. If that happens the dynamo is almost certainly serviceable.

[mickeytwonames]

Current conundrum
Ammeter not showing charge - but shows discharge
Dynamo checked and giving variable voltage output
F & D cables to regulator replaced so not in the loom.
Start car
Ignition light goes out
Both coils in the regulator - are magnetic to touch
BUT if I manually OPEN the Regulating coil contact, the Bridge coil closes, and the ignition light flickers on.
I have replaced the regulator with an older one, and the same issue happens (they are now switched back).
From what I can see from the wiring diagram, the charge goes back to the battery via the Ammeter to the starter solenoid connector.
The battery charging socket on the dashboard gives a reading of 12 volts when stationary.
If the battery is disconnected when the engine is running, the car stops
Any idea?
Regards
Michael