Morris Minor Owners Club

How can I measure the output of the dynamo, other than across the battery?

I only get 12.5V across, and that is way to little.

Problem is, that it is all new wiring, so it might be a wiring problem.
Hence the need to check the dynamo.

It is a shiney one, so I'd like to keep it

Onne

The workshop manual gives instructions for doing this, but they vary according to which regulator you've got. If you have one of the later type regulators, you have to do the measurements within 30s, or the shunt overheats and gives false readings. (They also assume you have the dynamo wired up right in the first place).

Basically, you disconnect the wires connected to terminals A and A1 from the regulator, and connect them together.

Then mesaure the voltage with the negative lead of your voltmeter on terminal "D", and the +ve to earth.

Increase the engine speed until the voltage wobbles then steadies. At this point, it should be 15.8v - 16.4v (at 20 degrees C). (16.1 - 17.4 at 10 degrees C). If it isn't, then either the regulator needs adjusting, or there is something wrong with the dynamo.

Check the fan belt isn't slipping.

Check the brushes have at least 7 mm of "meat" left on them and the springs aren't broken.

Check the field coil resistance is 6 Ohms.

If all that looks good, you are into adjusting the regulator. Come back if you want more detail. I would need to copy or transcribe the full text from the manual for you, as it is a bit complicated.

I have a workshop manual. I'll try the easy way first, with a known good dynamo.

Cheers for the info!

Onne