Dynamo or Alternator ?

[Camo]

Ok next question  ;D
I currently have a dynamo and am positive earth, the few times I had the car running before the head came off for the stuck valve I did notice the ignition light stayed on, now the car has been idle for 20 years and I am happy to replace the dynamo, but should I convert to negative earth, or go the whole hog and do an alternator conversion ?
I understand the car must be negative earth to carry the alternator, and it would be much easier fitting a radio with neg earth.
so what do I need to do to convert? I have read you swap the battery leads and the coil connections, but what else is required for keeping a dynamo set up, I read about re-charging the dynamo, what the heck is that about !! all simple instructions are welcomed..
thanks
Stuart

[heraldcoupe]

Hi Stuart,
Most likely you won't need to replace the dynamo. Check the regulator box which is mounted on the bulkhead behind the battery, chances are that there is some corrosion on the contacts which is causing problems with charging. Most people (including garage employees) don't realise that the regulator box is fully adjustable, very comprehensive instructions on setup are included even in the Haynes manuals. I reckon about 95% of regulator boxes which are replaced have nothing wrong with them - I shouldn't complain as it must be good for business!
To polarise the dynamo, take a feed wire from the live side of the battery and wipe it across the small dynamo terminal. You will get a few sparks so don't worry about it - job done. The only standard fitting on a Herald which is sensitive to electrical polarity is the heater motor, you will need to swap the connections as the motor will now be turning the wrong way with reduced output.
As regards an alternator it can be a benefuit with a car which is driven in all weathers or on regular short journeys, but most of my Heralds have coped perfectly well with an original spec charging system.
Cheers,
Bill.

[Camo]

thanks Bill, that sounds like a job I can handle, and I would rather keep a dynamo, just looks right, once up and running I shall try this but I have a list thats quite long still, but hey I wanted to tinker with old cars again, so I can't complain when theres tinkering to be done.
Stuart

[Ianp]

Now where have i heard that before?
tinkering ends up with full engine rebuild in my case  ;D

Ian

[Camo]

quick question..
<<To polarise the dynamo, take a feed wire from the live side of the battery and wipe it across the small dynamo terminal.>>
do I do this after I have swapped the terminals round, ie do I make the battery neg earth then swipe the terminal? or does it not matter?
thanks
Stuart

[heraldcoupe]

Hi Stuart,
You do this once you have the battery connected in it's intended polarity.
Cheers,
Bill.

[Camo]

great thanks Bill, she is now Negative earth ! easy when you know how  ;)

My ignition light is still on though, all connections seem ok at the box, will rough them all this weekend see if that gets the light off, failing that what else is next to check ?
Stuart

[heraldcoupe]

The external contacts are unlikely to be the cause, have you checked all of the contacts on the relays inside the box and carried out the adjustments in the workshop manual? I mentioned earlier that even the Haynes book is pretty thorough in dealing with setting up the charging circuitry. Without carrying out these steps anything I will tell you will be based on guesswork. Most garages are unwilling to test dynamo charging systems and will charge you for the new parts as they guess which one might be at fault. £30 for a dynamo and £20 for a regulator box, plus labour, when most likely it's only a matter of adjustment.
Cheers,
Bill.

[Camo]

Bill, if you were a woman I would marry you !
Your advice was spot on again and after some very quick reading in the manual and fiddling under the bonnet, my Voltage Regulator is working fine and my ignition light now goes out !! no need for a new dynamo, more money saved... many thanks

Stuart