Lucas MCR2 Voltage regulators

[petetherev]

Hello again Trevinoz,  I have refurbished (new field armature etc) my dynamo and checked out the regulator and I’m already to fit them. 
 I thought I would check out the other regulator I have, the one you said was for a 45w generator, its cold here and I can do it inside.
I think that the cover which showed the type, number, date etc. has been changed. The BSA Service Sheet 804 Reprinted May 1960 refers to both the MCR1 and the MCR2.  It quotes different electrical and mechanical settings for both.  My problems is where is says :-
 “Adjust if necessary to 0.025” (0.012” – 0.020” ), by removing shims “H” at the back of the fixed contact on an MCR1 regulator or by bending the fixed contact bracket on the MCR2 regulator.”

 The figures in brackets refer to the MCR2 regulator.  My regulator has shims therefore I conclude it must be an MCR1. The number stamped on the frame is 333141A  and 10 52 which I assume is the date.  Is there any way to confirm my thoughts please. I think the Lucas  numbering system is a nightmare.
Sorry to be such a pain.
Regards
Pete

[trevinoz]

Your regulator is an MCR2, the MCR1 is a smaller version on the same platform and has a smaller steel cover. There is also an MCR which was only made for a couple of years and is a bit different to the MCR1.
The MCR2 has shims as you have found. It's up to you whether you bend the contact or remove/add shims, depending on the clearance.
The first thing you should do with the regulator contacts is remove both and clean the surfaces, I usually use an oil stone.
The cut-out contacts are silver and are pretty easy to clean, unlike the regulator's tungsten.
If you want to convert it to 60W, just take two turns off the bobbin.

[petetherev]

Hello Trevinoz,  Thanks once again,  You obviously have a lot of knowledge of regulators.  I don't know what I'll do with it yet as the Regulator does not react to the DE test you advised.  I can only assume that the coil has failed.  I might take it apart and see if I can find the fault.  If nothing else it keeps me out of mischief.

Regards
Pete

[trevinoz]

Pete,
                  The DE test is testing the two shunt coils which are connected at one end to the bobbin which is at the same potential as the frame and the other to the earth terminal.
Normally you should get around 30 ohms resistance if both coils are OK, much higher if one is OK and infinity if both are open circuit.
You could lift the connections from the E terminal and try individually which will show whats what.
If they are open circuit I'm afraid that you will probably need donor coils from another regulator.
It's a fiddly job to change them as it means complete dismantling of the regulator.
I have done this successfully many times, sourcing components from regs which are badly rusted and have the resistor open circuit.

[petetherev]

Hello Trevinoz,  I have taken the 45W (MCR2)regulator apart and found the regulator coil broken where it attaches to the coil.  As I had nothing to lose I unwound it a turn cleaned the end of the wire and wound it around the mounting stud and put it back together and got it to both armatures to work. I got a DE resistance of 1.2 ohms.  I only did this for the exercise I have no intention of using it, I have always liked tacking things apart and finding out how they work and put together.

The 60W(RB107) which is the one I am/was going to use gave me a DE reading of 14 ohms..  Does this low resistance reading mean that this one is US as well or is there any way I can improve the resistance by cleaning and re-soldering the connections.

Regards
Pete

[trevinoz]

Pete,
                   I measured some resistances D-E on a few regs.
The MCR2 are all around 24 ohms.
One RB107 type was 28 Ohms and two others were around 14 Ohms.
I am not clear as to where the break was, the heavy winding or the fine and where exactly.
Not sure why the resistance is so low, overhaul the reg and see. If both armatures move I would expect the reg to work.
With 1.2 Ohm resistance, a fairly heavy current would flow and some heat would be generated.
Keep at it.
Cheers.

[petetherev]

Hi Trevinoz,  The broken winding was the light one inside the coil, as I said I took a turn off and cleaned up the wire drilled a small hole in the insulation fed the wire through ans wound it around the stud, reassembled the coil and rebuilt the regulator, it was only to see what happened I might have been able to make a better connection by removing the insulator where I had drilled the hole and soldered the wire. I might try it sometime.

It is the RB107 which I’m more concerned about as I said the armatures both ‘snap shut’ at 14ohms.  I’ll have to wait and see when I get to the starting the engine point.

Regards
Pete

[petetherev]

Hello Trevinoz, I’m sorry for not letting you know how I got on with my Voltage Regulator.

 I put my back out at the beginning of last year and was laid up for quite a while.   I then had to catch up with the normal maintenance jobs, as for this year I’ve no idea where its gone.

I cleaned the contacts reset the mechanical settings during the winter. I got  the engine running so I decided to set the regulation on the bike,  made up some extension leads, I thought 5minute job, I should have known better. 

I set the Regulator as specified in the service sheets without any trouble, a nominal 8v.
 The Cut Out is another story however.  Start the engine, and the dynamo output at tick over is about 6.5v and the Cut Out contacts close and don’t open until I shut the engine off  the. Adjusting the Cut Out screw does not have any effect. The battery voltage is about 6.2v

 I told you I’d checked the DE resistance as you suggested and got 14ohms I have since tested the coils individually and get 28.4 for the Regulator and 27.1 for the Cut Out, seems about right to me, reconnected and got 13.7.

Any ideas please

Regards
Pete