Uprated dynamo and control box issues

[ricky30dk]

Now I have the engine running somewhat steadily, I can turn my attention to the charging light that won’t go out. As far as I can tell, I have wired it all correctly and I have tested that the new Revington 28 amp dynamo is working, but the ammeter backs up the theory that the battery is not being charged. 

I have a new old stock  voltage regulator / control box fitted so I swapped this for the original (which worked 15 years ago), but with no change to the symptoms. I have read some of the older posts on here and can find useful links to instructions on how to adjust the VR/CB but I’m a little suspicious of why neither box works.......

So now I’m wondering if the upgrade from 22 to 28 amps means that the voltage regulator needs to be reset anyway. 

Does anyone here have experience with the 28 amp dynamo? (yes, I should have gone with the alternator, I realise that now)

cheers

Richard

PS attached a few pics of progress to date - those TRGB-type rollover hoops are causing some headscratching regarding how to stow the hood, if anyone has suggestions, I’m all ears (“get rid of them” is already on my list, though towards the bottom!)

[BlueTR3A-5EKT]

2 comments

Did you polarise the new Dynamo.  I would expect Revington to give that instruction.

Why bother with a dynamo?  Go for an alternator.  More readily available but do not look period.

 

Peter W

[RobH]

How did you test that the dynamo is working Richard? 

[ricky30dk]

Hi Rob, I connected both terminals with a wire and measured the voltage between that wire and earth - I think it was around 13V.

Hi Peter, I cannot be 100% sure I did - it’s been sitting in the car a while and I simply cannot remember - I’ll do it again - thanks for the reminder

[RobH]

10 minutes ago, ricky30dk said:

Hi Rob, I connected both terminals with a wire and measured the voltage between that wire and earth - I think it was around 13V.

 

 13 volts sounds way too low for a dynamo with full field current and off-load, but it does depend on rotation speed. This is the Lucas way:

http://mgaguru.com/mgtech/books/pdf/Lucas_Generator_and_Control_Box_Tests.pdf

 

[Z320]

Hi Richard,

I would double check all the connections of the cables, especially "field".

Polarisation is no problem at all: 

when you finished wireing close the contacts of the cut- out relay for a moment manual AND open it again.

That's it, BUT make really shure you opened the cut-out contact again.

If you don't do that it is no problem at all. When the regulator closes the cut-out  contact the first time himself

the battery makes the dynamo the correct field (with a single strong spark if the field was wrong).

Ciao, Marco

Edited August 4, 2019 by Z320

[ricky30dk]

Hi Marco - what a coincidence : I just fitted your fuel cap lock - it works perfectly 

I have spent most of the day trying to fix this and have learned more than I thought I would ever need to know about voltage regulators, but I haven’t solved it yet. I successfully followed the guide Rob linked to all the way up to measuring the open circuit voltage (between terminals D and E) - 3V at about 1500 rpm on the engine, which I took a wild guess was about 3000 rpm on the dynamo. No amount of adjusting the voltage adjustment screw caused any change to this, so I have to assume that I have some wiring connected wrongly somewhere. Should the coil pull the armature in? I set the gap at 0.5 mm but the coil doesn’t pull it in, or hold it if I press it down.

Electrical faults are my worst nightmare and I have been dreading having a problem with the VR.....time for a break and come back to it another day, I reckon.....

 

[ChrisR-4A]

Hi Ricky, looking at original workshop manual wiring diagram I’m not sure your connections on the control box are right. 

From the top as your photo manual shows:

E. = B. Black =   Earth

D. = NY. Brown/Yellow  2 wires

F. = NG. Brown/Green

A. = NW. Brown/White

A1. =NU. Brown/Blue  2 wires

Its difficult to see all the colours in the photo, and on my car the colours on the wires had faded and blue and green looked the same before I cleaned them.

 

Chris

 

 

 

 

Edited August 4, 2019 by ChrisR-4A
Added info

[Z320]

Hi Richard,

nice to hear the fuel cap lock fits.

Don't worry about electrical problems, you get that working.

First some simple explanation to the main functions of the regulator, it is

1st: a switch (the cut-out relay) to avoid discharging

2nd: a "reducer" to avoid too high voltage on high revs.

It can do nothing more.

On my TR4A to cut-out connects the dynamo to the battery on about 1.000 revs / 13 V,

the "reducer" starts working at already 1.500 revs / 15 V.

Next some word to the dynamo.

It has a minimum magnetism to poduce a minimum of voltage and current when you start the engine of the car.

This minimum voltage comes out of the big conector, goes to terminal D and is connected by the regulator direct to ferminal F.

This causes a much higher magnetism of the dynamo and an electric avalanche of voltage and current.

If you only measure 3 Volts on 1.500 revs there in no electric avalange.

I would short cut D and F on the regulator (don't worry, this is no problem), if this works the regulator is the problem.

If this does not work the dynamo should be the problem.

Perhaps you know the DC dynamo is also an engine, check it like this:

- put off the fan belt

- give 12 V in terminal D and F

- if the cables are still on the regulator: 12 V on D or F

Now it must run, if not the dynamo does not work.

Good luck, Marco

 

Edited August 5, 2019 by Z320
my bad english writing

[ctc77965o]

Stick battery volts on the F wire to the dynamo, with engine running should see full charge on ammeter. If not wiring or dynamo is faulty.. If yes then cutout in control box is dirty... Clean cutout contacts with fine abrasive, be sure to clean the debris from the abrasive out.. Now should see charge on ammeter. 

[ricky30dk]

thank you all for the fantastic advice - plus I already feel happier for sleeping on the problem! 

I will revert next weekend.

[Z320]

6 hours ago, Z320 said:

Perhaps you know the DC dynamo is also an engine, check it like this:

- put off the fan belt

- give 12 V in terminal D and F

- if the cables are still on the regulator: D or F

Now it must run, if not the dynamo does not work.

Good luck, Marco

 

Sorry me, mobile and light was already off when I remembered this:

with the fan belt off the generator pulley and all cables still in the correct position close the cut-out by hand.

Than the generator most run.

Edited August 5, 2019 by Z320

[ricky30dk]

Hi Chris,

I think I have the wiring right - maybe just looked wrong from that angle 

Hi Marco and Dave,

looks like a fault with the dynamo. When I close the cut out the dynamo rotor is stiff but it won’t spin. I’m going to fit the old 22A one and see if that works.

Watch this space!

[ricky30dk]

except it seems that I, who never throws anything away, threw it away 

I have a new LRA100 in the attic - shall I just fit that and to hell with the dynamo?

[Z320]

Hi Richard,

I know no case of the generator gets stiff.

Please let me check tomorrow on my TR4A.

Ciao, Marco

 

[ricky30dk]

Thanks Marco,

also I get a spark when I release the cut out 

[Z320]

2 hours ago, ricky30dk said:

Thanks Marco,

also I get a spark when I release the cut out 

Yeah I know,

this is bacause with this you switch the generator as an engine with about 200 - 300 Watt.

Not fine but for a test it is OK.

Was on my car and also worked with my spare dynamo.

How ever I switch them, F and D, I never get the dynamo stiff, yours is out of order, I would send it back.

In details:

Voltage on F and D: the pulley runs slowly and powerfull, don't try to stop it.

Voltage only on D: dymamo runs fast but weak because of own magnetism 

Voltage only on F: nothing happens

Hope this helps, Marco 

[RogerH]

16 minutes ago, Z320 said:

 

Voltage on F and D: the pulley runs slowly and powerfull, don't try to stop it.

Voltage only on D: dymamo runs fast but weak because of own magnetism 

Voltage only on F: nothing happens

Hope this helps, Marco 

So, can we throw away the engine and just use the dynamo  

 

Roger

[Z320]

You are a genius!

With this idea you can save the world!

Edited August 11, 2019 by Z320

[ricky30dk]

Hi Marco,

thank you so much for your help with this - it’s the final obstacle that prevents me setting up the car for driving.

I ran a final test with the loom disconnected, based on your suggestion above, with the following result :

battery connected to both F and D : dynamo runs 

battery connected to F : nothing happens

battery connected to D : dynamo doesn’t move on its own but is stiff and jerky when I turn it by hand

Depending on what you think, I can call Revington and see what they say - they might not take it back after 3 years and with extra black paint on it, but they might have a suggestion of how to fix it.....

cheers

Richard

[Z320]

With "the new Revington 28 amp" I thought it is new....

If it is the same construction as the C40 shure you gave the rear bearing always some oil?

If it is 3 years old I would put it in pieces and see what I can found.

Ciao, Marco

[ricky30dk]

Hi Marco,

it’s new in that I have never used it, but it’s been in the car since I bought it three years ago. Should I have oiled the bearing even if it wasn’t being used? I can certainly take it apart would be good to know what I was looking for 

[ricky30dk]

I’ve been restoring this car for many years - so long that some of the parts I bought along the way have suffered, even though they have been kept inside (foam padding for example). I drove it into the workshop 15 years ago and everything was working then, even if it was very worn out. I thought I’d kept all the original parts but for some reason I threw out the dynamo....

[Z320]

You bought the dynamo, fixed it but never drove the car for a noticeable distance?

In this case I would tell / ask Revington.

[Lebro]

Sounds like the ball race (at the front) has gone rusty, & is the cause of the "lumpyness"

Bob.