Dynamo testing

[Onne]

As some of you know, I have been tinkering with a Morris 10/4 from '33 last weekend. I have set the car back to +ve earth again, the fuel pump is working, engine runs a treat. Now comes the problem. The dynamo doesn't seem to be charching at all. Could be wires from the thing to the battery or, the thing itself. I have removed the dynamo from the car. Is there any way of testing it with a multi meter, or should I just bring it to the specialist? the whatsitcalled (carbon..) seem to be all right, not 100% though.

Onne

[Willie]

ONNE... I assume that you know that you have to repolarise the
dynamo if you have changed the cars polarity?? See under technical
tips. If you mean the CARBON BRUSHES then they are still ok if the
area which touches the commutator is nice and shiney. If sooty and
burnt in appearance then they are probably worn too short. Each
copper segment on the commutator should give a resistance reading
to the next one, any open circuit ones are a problem.

[Onne]

The dynamo wasn't polarised in the first place, so I presumed it would still be +ve earth. I will check the commutator.

Thanks for the help so far!

Onne

[Onne]

Just did the measurements, only 1,2 Ohm at best, so the dynamo is just knackered and will have to be replaced.

[Alec]

Hello Onne,
what measurement is 1,2 ohms?
a quick check for a dynamo is to (off the car or at least with the fanbelt off) is to connect the main and field terminals together (big and little spades) and apply 12 volts, if it's OK, it should spin. i.e motor. with little or no sparking at the brushes.

Alec

[Onne]

I can't check my own at the moment, but the one off the 10/4 only has two little terminals on top. Onle these two tiny wires connect it to the rest of things.
I have had it tested professionally toady, and it seemed to be working OK.

I will try your method, if not for tesing, just for the fun of it!

Onne

[Willie]

ONNE... If the 1.2 Ohms is the value between each segment of the
commutator and the next one then, as long as they ALL read the same it is most probably ok.

[Onne]

Thats what I measured. But what to check next? I have got a wiring diagram somewhere, and I'll measure the resistance in the wire from dynamo to Voltage regulator. Any other ideas?

Onne

[Willie]

ONNE, well if your garage said the dynamo is ok and you confirm
it by using ALECS method that should make things a little clearer!!
(famous last words). I hope you find an enormous resistance in
the dynamo leads, but I doubt it.

[Onne]

If that is all OK, how should I procede? Can I do measurements on the regulator? It is actually quite Minorish. When I say this, of course I can do measurements, but I'd like them to make sense too......

Will try ASAP, problem is the starter moter on the Celica has just died last nght, so I don't have any cars at the moment.

Onne

[Willie]

I have absolutely no knowledge of the system on a Morris which is
that old, perhaps Alec does? Or, is there an on-line site for the
pre-war Morrises??

[Onne]

Who knows.... Still, it looks quite similar to that of our modern (...) Morrises. Still, I'll have to sort out my Toyota first, starter moter still not replaced, as I can't get hold of a replacement. Again I just LOVE Minors, with their great parts supply