Dynamo fiasco

Post by **guystrungout** » Tue Oct 20, 2009 5:18 pm

Bit long winded this, but I'll try and keep it as brief as possible..
Problem being when its dark my radio won't work when the headlights are on and before I fitted Halogen headlamps, it worked but stopped working when I pulled up and braked, ie when the brake lights were lit.

A friend of mine said it could be the regulator box and bearing this in mind I dug out a secondhand regulator box I have had kicking about for years that was working when I took it off the mog I scrapped long ago. I have just fitted it this afternoon and when I started the engine the charging light would not go out.
Ok, so I refitted the original regulator as I knew this problem wasn't there with the old one, but hellanddamnation the ignition light stayed on again but went dimmer this time.
I have checked all the connections and refitted both the connections on the back of the dynamo but all to no avail. And now I am really stumped.

Anyone have any ideas?

Firstly, is there anyway of improving my radio listening whilst driving on dark nights or will I have to resort to replacing my dynamo with an alternator? And secondly, what have I done in changing the regulater box that has caused my ignition light to stay on?

All advice gratefully recieved as I'm now stuck in the garage and dare not go out in case I conk out with a flat battery!

Post by **PSL184** » Tue Oct 20, 2009 5:22 pm

Have you connected the wires to the correct terminals? The ign warning light should be coming off the 4th from left terminal and is yellow/green (from memory). Next put your meter across the battery and check what voltage the battery is seeing - The dynamo may not be charging enough and the light may be on for the right reasons.....

Post by **guystrungout** » Tue Oct 20, 2009 5:39 pm

Yes all wires were carefully removed and replaced individually to avoid the problem of getting totally confused! I will check the voltage at the battery, any ideas what it should be? 13.9-14v?

Post by **PSL184** » Tue Oct 20, 2009 5:42 pm

Anything over 13 volts should be enough to put light out but ideally you want 14.5 volts with no load on the battery and 13.5 with headlamps on.

Post by **bmcecosse** » Tue Oct 20, 2009 5:45 pm

Yes - should be just under 14 volts. The 'radio' problem is probably down to a poor earth connection on the radio - certainly it's nothing to do with dynamo/alternator. You must have messed up the wiring when swapping regulators - don't listen to that 'friend' again! Check and double check the wiring.

Post by **guystrungout** » Tue Oct 20, 2009 5:59 pm

Have just been out and checked the voltage across the battery when running, 11.9-12 at full revs. Oh dear. Light dims but stays on.
All the wires went on in the same order they came off, I did each one one at a time to avoid confusion.
I don't know if this has any relevance, but the regulator I was hoping to replace the one already on the car with was a later version, the one that was on the car already was an early one with screws instead of spade connectors. I removed the wires and fitted spades to them and then fitted them on to the replacement one at a time to avoid trouble.
So much for that!
I have now put the original one back on but the charging light doesn't go out but goes dimmer. As I already mentioned..
I will go out and check all the wires once more, unfortunately some one previous to me has messed with the wiring and there are some newer wires alongside the original old fabric covered ones, all of which seem to be of a similar colour, which doesn't help.
The dynamo was working fine previous to this and the battery was disconnected when I swapped the regulator boxes so it is very confusing...

Post by **guystrungout** » Tue Oct 20, 2009 6:18 pm

Just been out fiddling again and noticed the light is dim on tickover and gets slightly brighter on revving engine....any clues?

Post by **PSL184** » Tue Oct 20, 2009 8:18 pm

Take the middle wire off the regulator and measure the voltage between that and battery earth first.

Post by **bmcecosse** » Tue Oct 20, 2009 9:02 pm

It's certainly not charging at these volts - so there must be a mix up! You haven't reversed the polarity or anything at the same time as doing all this ? I would dispense with all the non-standard wires at the moment - just use the original wires.
Print out a copy of Barry's excellent little wiring diagram from the 'sticky' at the top of this section - and have it with you at the car. I do suggest you make sure the earth connection from the regulator is going to a good earth - perhaps even run a temporary connection directly to the battery earth from that earth terminal to see if it sorts things out.

Post by **guystrungout** » Tue Oct 20, 2009 9:28 pm

Ok, thanks I'll do all that you've suggested in the morning. Its chuckin it down out there now and its dark and cold.
I think the bad earth theory is a feasible one, I honestly didn't mess with anything other than move wires one at a time from one connection to another, but one of the earthwires was tucked under a wire to the fuse box and I had to give it a slight pull to get enough slack to untangle it, so it sounds like a likely culprit. Hopefully, anyway. Fingers crossed.
Thanks for your help as always, I'll let you know how I get on tomorrow.

Time for a beer I think!

Cheers.

Post by **mike.perry** » Wed Oct 21, 2009 11:23 am

Have you checked the dynamo brushes?
Is the fan belt tight?

Post by **guystrungout** » Wed Oct 21, 2009 11:39 am

Good morning.... the continuing saga... (at least its not raining at the mo..)

Checked the earth and tried a temporary one, all good, no probs with the earth, annoyingly. Ran the motor for a while checked voltage at middle terminal on regulator, is roughly 8-10 volts dropping when engine revved. Is this normal? I'm assuming it is.
Checked small wire on dynamo which seemed to be kicking out up to 13.3v, varying. Big wire was kicking out around 13.5v.
Checked battery agin, voltage up to around 13.5v, checked charging light and it had gone out. Thought I'd sussed it.
Cleaned battery terminals and their respective attachments at opposite ends of cables and started engine again, charging light stays on dimly.
Ran through testing voltage at various points again, similar results. Checked charging light, it was out again.
Started car, light on dimly, ran it for a bit and put on headlights, small wire on dynamo read 12.3v, big wire 12.4v. Battery red 12.5v with lights on.
Does this point to anything specific? Is my regulator not up to scratch? The battery is good, the dynamo is good too, why would the charging stay on dimly and then go out after roughly 5 minutes?
I wish I'd never started this crazy job.

Post by **guystrungout** » Wed Oct 21, 2009 11:44 am

Fan belt isn't tight but not slack enough to cause problems, it was one of the first things I checked. Brushes should be good, they were near as new last october and I've only done 10,000miles. Might be worth checking them I guess. Seems odd that it was all working fine, apart from radio problem when lights were on, and now its all gone silly just for trying to change the regulator. Such is the nature of fiddling with vehicles I suppose! There's a lot to be said for not fixing it til its broke!

Post by **guystrungout** » Wed Oct 21, 2009 2:20 pm

Well I wasted a good few hours this morning and then went to see a friend (a different friend!) who worked as an autoelectrician 35 years ago and he had a play about but the conclusion he came to was to replace the regulator. He tested them both and got them both to worlk but not without messing around with them and they wouldn't perform on their own as they should.
So the moral of this tale is don't use parts that have been sitting in an old toolbox for 25 years, buy a new one! AND of course, leave well alone unless its broken.
I just hope it makes listening to the radio at night a bit easier....<br>[img]http://mmoc.org.uk/mbimage.php?

Post by **rayofleamington** » Wed Oct 21, 2009 4:01 pm

I'd get another radio!
If you're lights work, and you're not getting frequent flat batteries then the charging circuit is not so bad.

Post by **mike.perry** » Wed Oct 21, 2009 4:40 pm

Listen to the engine instead of the radio. It makes a much better noise.

Post by **guystrungout** » Wed Oct 21, 2009 6:21 pm

Well the radio worked fine for years in another car, and it works fine in daylight. It got worse when I fitted Halogen headlamps although it did use to cut out at traffic lights and junctions which through me for a while. Until I realised it was when the lights were on (pre-halogen) and the brake lights were activated. But now it only works for 15 or so minutes before trailing off to nothing which seems to point to all the power going else where and not enough juice to power a tiny radio feed!
Maybe my shiny new regulator may help...or is that just wishful thinking?!

<br>[img]http://mmoc.org.uk/mbimage.php?<br>[img ... 45658_8189[/img]<br>

Post by **PSL184** » Wed Oct 21, 2009 7:05 pm

The radio )although 12v) will work best when it is receiving 13.8 volts (design condition). That is why I said to check that you have at least 13.5v when lights are on etc. The new reg (if adjusted correctly) should solve the problem for you.

Post by **bmcecosse** » Wed Oct 21, 2009 7:38 pm

I suspect that when you rigged the temporary earth - that pulled the Regulator 'Cut -out' IN - and it started charging - and kept on charging - until you stopped the engine. Then you took it all away - and back to square one. Try it again - with a good earth.

Post by **guystrungout** » Wed Oct 21, 2009 10:11 pm

You could be right about the earth, but the earth was good when I tested it but I added a temporary one for good measure anyway. Certainly something was kicked in because the voltage went up on the battery at some point.
Funny old buisness, how just disconnecting and reconnecting can throw something into malfunction like that, but then the poor old regulator is probably as old as the car which is 54 yrs so I figure its allowed to be worn out after all this time.
I hope the new one lasts as long!