another dynamo post!

Post by **delta558** » Sun Aug 03, 2003 1:33 pm

Hi all,
I recently had a problem with the ignition light staying on all the time. Oh well, Dynamo's gone. So I removed it and had a look inside - there was a thin line of silver, which I'm told means that it has thrown the solder due to overcharging. So I replaced the regulator, put a new dynamo on and it's still not charging. I've checked the fan belt tension and all is as it should be. So I'm wondering what else could be the problem - Any suggestions? I've read though all the previous posts involving dynamos and Willie mentioned something about the wiring, but I have to admit that at the moment I'm completely stumped!
Also, linked with this, the lights have stopped working - I assume because the battery is constantly losing power when the engine is running, but I can't even get a faint glimmer from them with the ignition on and the engine stopped. I took the car for a short drive, and when I turned the lights on, the engine died!!! Is it possible I may have a severe electrical problem and need a new wiring loom? Or am I jumping the gun a bit there?
Any help would be greatly appreciated.

Post by **Willie** » Sun Aug 03, 2003 10:03 pm

Oh dear,you do have problems. A bit confused,you say
the lights aren't working but that you were driving the
car! Is it now 'dead' or does it still start? I think the
post you referred to was when I advised the checking
of the earth connection which is bolted to the bulkhead
behind the vertical wiring loom which feeds the coil and
dynamo etc(it is about 4 inches above the step on which
the battery sits). It was unfortunate you renewed both
the dynamo and the control box at the same time as
now you are not sure where the original fault was. it is
quite easy to check the dynamo output but you do need
a test meter. Do you have one? (by the way,it is not
necessary to have the ignition 'on' when you are checking
the lights).

Post by **delta558** » Sun Aug 03, 2003 10:42 pm

Hi Willie,
Thanks for the reply. Yeah, the car still starts. The 'confused' bit about the lights - I was driving the car home, it was beginning to get dark so I turned the sidelights on. At this point, the car lost all power and died. I couldn't restart it, so I got towed home (only a mile or so, and I couldn't be bothered to start fiddling on the roadside!) The car is now on the drive and will start, but will not charge (ignition light stays on and ammeter stays the wrong side of zero). The lights will not turn on at all - not even the faintest glimmer.
I bought the car 3 months ago, and have been using it as a daily driver without any problems at all, and now it's all gone at once. And I'm determined to be on the rally from Milford Haven to Tenby on September 7th (my first chance to get out and about and meet other Minor owners)
With regards to the dynamo and control box, yes I know it's awkward having replaced both but I know the dynamo had gone and suspected that it was caused by the box - I didn't want to blow another dynamo by not replacing the box.
I haven't got a test meter yet - I initially worked out that the dynamo wasn't giving out a charge by using a couple of wires on the spade connectors and trying to get a spark between them. I know it's basic, but it was all I could do at the time.

Post by **grainger** » Mon Aug 04, 2003 2:51 am

if you got a new dynamo was it negative earth already or do you have to set them one way or the other ?

just a thought - they may be supplied as positive earth as the car would have been originally, i presume you are now negative earth ?

ps i dont think you would get a spark between the two spade connectors - to check the dynamo you have to connect both outputs together then take a meter reading between that and an earth, while the car is running.

cheers
grainger

Post by **Willie** » Mon Aug 04, 2003 7:58 pm

Grainger is right....if you removed the two wires at the rear
of the dynamo and then connected the two terminals together
with a piece of wire and then flicked this wire to chassis you
would see a spark if the dynamo was functioning, but as you
say its a bit basic. If you DO have NEGATIVE earth then
you could try the remagnetising exercise...remove the two
dynamo leads, connect a wire to the small terminal only and
then touch this wire on to the POSITIVE battery terminal for
about five seconds, DO THIS WITH THE POSITIVE BATTERY
LEAD DISCONNECTED FROM THE BATTERY BUT WITH THE
EARTH LEAD CONNECTED. Put it all back and pray that the
red light goes out.

Post by **delta558** » Tue Aug 05, 2003 10:47 pm

Thanks again to both of you for your replies.
You're right that the dynamos are supplied positive earth, Grainger, but my car is still very original in some respects (though modified elsewhere) and it is positive earth. So no conflict there.
I've just bought myself a test meter, and have to admit that I'm very proud of myself - I now know that the fuses are working. That's it. In case you hadn't guessed, I'm very new to all this and haven't really worked out the meter yet.
I think maybe the electrical problem (lights) is a secondary problem - they seem to work some of the time when the engine is off, but not at all when the engine is on. Maybe it's just a loose connection somewhere. The horn works all the time, so I'm going to trace the wires from the light switch and see if there's damage anywhere.
My earth connection hasn't been touched at all, and it was good before the dynamo problem and seems clean enough now, so I don't think that's the cause.

I think I had better bow to the inevitable, and book the car into the garage to get it sorted (I can already hear Denise - "but you said it would be an easy car to work on . . ."). Again, many thanks for the help. I'll let you know what happens - it's probably something ridiculously simple which is staring me in the face!

Cheers 'n' beers,
Paul.

Post by **delta558** » Sun Aug 17, 2003 1:56 am

Car's fixed now, thought I'd post this just to explain the problem and to remind people never to ignore the obvious - My dynamo DID need polarising, as Grainger suggested. However, the donor car from which I got the dynamo was positive earth as is my car. So I just assumed all would be okay. In my case, for some reason it wasn't but I was sure that it couldn't be the problem. All is well now, though, so I'm back on the road.

The other electrical problems were caused by a rotten fuse box and lots of unnecessary wiring (alarm used to be fitted, it was removed but the wiring was left and not tidied up properly by a previous owner) and also by some wiring which was just falling to pieces!

The auto-electrician sorted it all out and you'd think it was all new. Total cost was £164. Not bad, really!

Post by **grainger** » Tue Aug 19, 2003 9:37 pm

great ... it still sounds like a lot for a few wires - but its something you wont have to think about again

as for it being an easy car to work on, give it 12 months and you WILL know every nut and bolt, you just have to ... but there isnt many so it IS relatively easy

the dynamo thing was a good guess as i bought a new one just before me other saloon died and so i havent had to use it yet, but i was thinking they probably come reconditioned as positive earth, or maybe NO earth at all !!! so if i ever have to use this one i'll know what to do

saved me £164 quid there ....

cheers
grainger