Morris Minor Owners Club

To force the dynamo to full charge - just run a +ve lead connection (assumes -ve earth) to the F terminal on the dynamo - it should go to high volts - and the regulator 'Cut-out' should Cut IN right away - with the volts heading ever upwards. And yes -as above - the dynamo should 'motor' if it's ok.

bmcecosse - can I do this with the Dynamo in situ?

Yes! For 'motoring' test - pop the fan belt off.

mike.perry wrote:If you remove the dynamo and connect the terminal to the neg term. of the battery and the body to the pos term of the battery (assuming the car is still pos earth), with a pair of jump leads the dynamo should spin.

Yes it does, like a good'n. I thought this meant that the Dynamo is ok. I tried the "force the dynamo to full charge" test though and there was no difference in the reading across the battery.

Could the Dynamo motor and yet still not charge the battery?

Today a customer of mine offered to take the pulley off the dynamo and get a replacement at a local spares place at trade price - unless anyone has any other ideas.

If it motors - it's fine! The problem lies in the regulator box - or the wiring. For a better 'charge' test - join both terminals together on the dynamo (removing all standard wiring for now) - and connect them to a lead - start the engine and run at fast idle - join that lead directly to the battery +ve terminal - it should now be charging hard - the battery volts should rise. Take the lead off the battery before you switch off!

Just thought I'd post the outcome of this. Trev is working again. In the end I passed him to an auto electrician in the village, and he determined that the Dynamo was indeed faulty. He said that the regulator had been played with and had caused solder to fly off inside the dynamo (he explained it much better than this). He fitted a new dynamo and also the spare regulator I had and now all is well.

Thanks to everyone who has tried to help. I would like to have fixed it myself but at least I have learnt an awful lot.

Simon

Thanks for the update, always nice to hear how things turn out.

That dynamo must have been getting pretty toasty to melt the solder .