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Adjusting a Lucas 6 volt voltage regulator.... #443952
07/10/12 4:10 am
07/10/12 4:10 am
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Torch2 Offline OP
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is testing and adjusting these something that can be done by a laymen or is it really a ancient secret voodoo practice?

Last edited by Torch2; 07/10/12 4:19 am.
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Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Torch2] #443966
07/10/12 9:14 am
07/10/12 9:14 am
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Not a secret voodo practice, but in my experience, when these regulators give you trouble, you just can't win (in most cases anyway) and that is why many opt for a electronic regulator, and if these old things work ok, leave them well alone !

It is possible (in theory) to adjust these things yourself, so you may give it a try.

Here is the procedure:

Disconnect one of the leads of the battery.
Connect the negative lead of a voltmeter between the "D" terminal of your dynamo (leaving dynamo wiring in place).
Connect the other lead of the meter to a good ground (earth) point on your bike.
Start your engine, and increase engine rpm slowly untill you have a stable reading on your voltmeter.
The meter should read 7.8 to 8 Volts now.
If the reading is less than 7.8 Volts, stop the motor.
Turn the regulator screw Clockwise by a very small amount.
( the regulator screw is the one on the RH side when looking at the regulators backside)
If the voltage reads too high, (8V or above) the screw must be turned counter-clockwise of course.

The other regulating screw, (the one on the LH side) is the reverse current cutout adjustment.
This one needs to be adjusted when the cutout points stay closed after the motor speed has decreased below the generaror charging level.
This can be checked by reading a discharge on your ammeter (if your bike is equipped with one).
If this is the case , turn IN (clockwise) the LH adusting screw slightly.
Failure of cutout may be caused by a too large gap of the contacts.

Hope this helps you a bit, you may give it a try, and if nothing else helps, you may consider buying a electronic regulator.

Please note that the adjustments are to a certain extend temperature sensitive, and the figures here are for average temp of 20 deg C.
If you live in So-Cal,(I figure that the heat can be quite extreme in your area) you may have to adjust to a slightly lower voltage

Last edited by Peter R; 07/10/12 9:26 am.

Peter.
1974 Commando 850
1972 Trident T150T
1961 Goldie DBD34
1969 Benelli 250 sport special
Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Torch2] #444021
07/10/12 3:45 pm
07/10/12 3:45 pm
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thanks Pete, that is what I needed, I have about 7 old regulators that I want to try and revive, Me and several other customers have given up on Podtronics solid state regulators after several of them have failed on bikes, at $100 a wack it's starting to get expensive, I have seen the Wassell brand for sale at about 1/2 the cost of a Podtronics but typically Wassell is not known for quality. I have also seen a Lucas solid state but it too failed. The generators all test out fine and they seem to work well on an old points regulator when you can find a good one.
I did adjust one points regulator and it worked fine for a while, I have heard that they like to have a decent battery and then I've seen others work well without a battery.

Last edited by Torch2; 07/10/12 3:51 pm.
Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Torch2] #444035
07/10/12 5:46 pm
07/10/12 5:46 pm
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In my experience, the regulator portion of the MCR2 device can be made to work quite well, but the set point of the reverse current cut out in the newer style MCR2 can be unstable as it ages.

A while back I had given some thought to a hybrid modification ... retaining the mechanical regulator and adding an electronic cut out, but it may be just as inexpensive to buy a complete solid state unit.

I like the PODtronics regulator, although there are others to choose from made in the UK.

..Gregg


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Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: gREgg-K] #444058
07/10/12 8:58 pm
07/10/12 8:58 pm
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Originally Posted By: gREgg-K
, but the set point of the reverse current cut out in the newer style MCR2 can be unstable as it ages.
The resistance of the cutout contacts (and the regulator contacts) should be less than 1/2 Ohm. But, when not used for some time an insulating oxide slowly grows on the points. Oxygen has no trouble permeating the space so the oxide grows even if the points are closed. I measured over 20 MOhm for the points in a new-old-stock regulator, which shows what an issue this can be. This increases the resistance to where it causes issues with the regulation. The transient current flow during opening and closing of the points during normal operation basically burns away the oxide, keeping the regulator functioning properly.

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Magnetoman] #444111
07/11/12 7:52 am
07/11/12 7:52 am
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"burns away the oxide"

Sounds a bit contradictory? I know what you mean tho'. We call it contact wetting in telecomms.

Bob


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'95 Daytona 1200
'98 Daytona 1200 dragbike
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Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Magnetoman] #444154
07/11/12 2:38 pm
07/11/12 2:38 pm
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Originally Posted By: Magnetoman
Originally Posted By: gREgg-K
, but the set point of the reverse current cut out in the newer style MCR2 can be unstable as it ages.
The resistance of the cutout contacts (and the regulator contacts) should be less than 1/2 Ohm. But, when not used for some time an insulating oxide slowly grows on the points. Oxygen has no trouble permeating the space so the oxide grows even if the points are closed. I measured over 20 MOhm for the points in a new-old-stock regulator, which shows what an issue this can be. This increases the resistance to where it causes issues with the regulation. The transient current flow during opening and closing of the points during normal operation basically burns away the oxide, keeping the regulator functioning properly.


Different issue, Magnetoman. I'm not talking about oxidation of the contact faces; rather, the inability of the later style contact set to hold an adjustment (hence my term "unstable").

This happens because the output current passes through the stationary contact of the cut out; and over time, heating from overloads tends to anneal the supporting metal so that it will not maintain its setting.

..Gregg


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Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: gREgg-K] #444179
07/11/12 4:01 pm
07/11/12 4:01 pm
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Originally Posted By: gREgg-K
I'm not talking about oxidation of the contact faces; rather, the inability of the later style contact set to hold an adjustment (hence my term "unstable").

This happens because the output current passes through the stationary contact of the cut out; and over time, heating from overloads tends to anneal the supporting metal so that it will not maintain its setting.
If you calculate the resistance of the supporting metal through which the current flows it's less than a milliohm, so Joule heating in it from even a 10A overload current is less than 0.1 Watt. The contact itself, if it has not oxidized, contributes less than ~0.1 Ohm, which means even under overload conditions 10 Watts is dissipated there. If none of that heat is dissipated in the air, and all of it is has to be conducted away along the supporting structure alone (i.e. heating it), I calculate that the temperature rise at the contact will be 40 oC (dropping linearly from that along its length to the temperature of the housing itself). Even under these worst case assumptions, this temperature is so low that even long term softening of the steel support should be truly negligible. However, if the contacts have oxidized, significantly more heat will be generated in them, which in turn will increase the rate of oxidation, increasing the heat further, ...

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Phatt Bob] #444228
07/11/12 8:22 pm
07/11/12 8:22 pm
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Blimey! DC wetting. That takes me back a few years. (Post Office Telephones!!!)



Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Magnetoman] #444236
07/11/12 9:36 pm
07/11/12 9:36 pm
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Originally Posted By: Magnetoman
If you calculate the resistance of the supporting metal through which the current flows it's less than a milliohm, so Joule heating in it from even a 10A overload current is less than 0.1 Watt. The contact itself, if it has not oxidized, contributes less than ~0.1 Ohm, which means even under overload conditions 10 Watts is dissipated there. If none of that heat is dissipated in the air, and all of it is has to be conducted away along the supporting structure alone (i.e. heating it), I calculate that the temperature rise at the contact will be 40 oC (dropping linearly from that along its length to the temperature of the housing itself). Even under these worst case assumptions, this temperature is so low that even long term softening of the steel support should be truly negligible. However, if the contacts have oxidized, significantly more heat will be generated in them, which in turn will increase the rate of oxidation, increasing the heat further, ...


I take it that you are attributing the heating I noted being due mainly to oxidization of the contacts. If so, then you must also take into account the resistance added by that oxide layer into your calculations ... which as you point out above, can quickly become very high.

That being the case, with this highly resistive layer on the contacts, how could a 6 volt dynamo produce enough voltage to dissipate that sort of power?

.. Gregg


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Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: gREgg-K] #444239
07/11/12 9:46 pm
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Originally Posted By: gREgg-K
That being the case, with this highly resistive layer on the contacts, how could a 6 volt dynamo produce enough voltage to dissipate that sort of power?
Can you reword your question? The voltage produced by the dynamo does not dissipate power, so I'm not sure what it is you mean. Please restate.

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: tbird649] #444243
07/11/12 10:03 pm
07/11/12 10:03 pm
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Originally Posted By: tbird649
Blimey! DC wetting. That takes me back a few years. (Post Office Telephones!!!)
I had never heard this term before, but thanks to google I see it is the same phenomenon that happens to Lucas regulator contacts when they sit unused for a while. Since oxidation was a problem with contacts in telephones in England, and since most phones don't sit unused for weeks at a time, this shows that the oxide resistance grows fairly quickly.

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Torch2] #444283
07/12/12 3:20 am
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so, it is secret voodoo science......

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Torch2] #444290
07/12/12 5:18 am
07/12/12 5:18 am
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Originally Posted By: Torch2
so, it is secret voodoo science......
It certainly would be easier to explain it that way.

It's really not that difficult. For quite a while Lucas used spring clips on their regulators to let any motorcyclist with a screwdriver have easy access to the settings. I'm surprised it took them as long as it did, but they eventually realized that owning a screwdriver wasn't a sufficiently strict IQ test, and as a result they switched to "permanent" crimped-on covers.

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Magnetoman] #444293
07/12/12 7:39 am
07/12/12 7:39 am
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"Blimey! DC wetting. That takes me back a few years. (Post Office Telephones!!!)"

Thread hijack alert!!!

I was with BR who adopted PO telecomms practice, if I mention Honeywell keys and 62 type equipment you'll know what I mean. As you say a few years, pre TEP1E and ETSI? We got round the problem by constantly trickling a few mA thru the closed contacts. not possible on a CVC I think.

Bob


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'98 Daytona 1200 dragbike
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Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Magnetoman] #444303
07/12/12 10:37 am
07/12/12 10:37 am
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Originally Posted By: Magnetoman
Originally Posted By: gREgg-K
That being the case, with this highly resistive layer on the contacts, how could a 6 volt dynamo produce enough voltage to dissipate that sort of power?
Can you reword your question? The voltage produced by the dynamo does not dissipate power, so I'm not sure what it is you mean. Please restate.


Assuming your statement is a genuine attempt to better understand my statement ... the voltage produced by a dynamo *causes* power to be dissipated in the circuit, according to the current flow allowed by the resistance of the various branches.

If as you say, the cut out contacts oxidize so that its series resistance increases substantially, the dynamo can not produce enough EMF to overcome that large increase in resistance (at least, not to the point that appreciable power is dissipated in the branches).

Rather, with the regulator holding its output voltage at a max of 7.8V or so, if the oxidization resistance increased to the megohm levels you cited, the current flow throughout the circuit would drop to microAmp levels and significant heating could not occur.

But, I think we both know you knew that...

... Gregg.


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Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Magnetoman] #444314
07/12/12 12:46 pm
07/12/12 12:46 pm
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Originally Posted By: Magnetoman
Originally Posted By: Torch2
so, it is secret voodoo science......
It certainly would be easier to explain it that way.

It's really not that difficult. For quite a while Lucas used spring clips on their regulators to let any motorcyclist with a screwdriver have easy access to the settings. I'm surprised it took them as long as it did, but they eventually realized that owning a screwdriver wasn't a sufficiently strict IQ test, and as a result they switched to "permanent" crimped-on covers.


Yes, but even then, the "permanent" crimped on covers found on the RB108 had easily-removable rubber bungs to allow access to the adjustment screws. Worse, those units also dispensed with the adjustment lock nuts found on the earlier MCR's, making unauthorized adjustment even easier!

I don't think Lucas was quite as deliberate in limiting access as we might want to think : I have an RB108 here without rubber bungs date coded 1957, while a later one, date coded 1963, does have removable bungs.

Agreed however, that only those persons with the requisite knowledge and skill should attempt adjustment.

... Gregg


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Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: gREgg-K] #444339
07/12/12 2:51 pm
07/12/12 2:51 pm
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Originally Posted By: gREgg-K
Assuming your statement is a genuine attempt to better understand my statement ... the voltage produced by a dynamo *causes* power to be dissipated in the circuit, according to the current flow allowed by the
Yes, it was completely genuine. Your wording is unusual, but now I understand what you meant. However, saying voltage *causes* power to be dissipated is a confusing way to describe a circuit.
Originally Posted By: gREgg-K
If as you say, the cut out contacts oxidize so that its series resistance increases substantially, the dynamo can not produce enough EMF to overcome that large increase in resistance (at least, not to the point that appreciable power is dissipated in the branches).

Rather, with the regulator holding its output voltage at a max of 7.8V or so, if the oxidization resistance increased to the megohm levels you cited, the current flow throughout the circuit would drop to microAmp levels and significant heating could not occur.
Specific ways of describing circuits have been developed to avoid confusion. This isn't nit picking, since mixing concepts of volts and power easily leads to incorrect conclusions. In this case, whether or not the dynamo can produce "enough" EMF, that EMF doesn't "overcome" resistance. You added the parenthetical expression "(not to the extent...)" that lets me understand what you meant, although the text just before it talked about overcoming resistance. If some element in the circuit becomes resistive, most of the EMF drop occurs across that element (although, not because it "overcame" the resistance). This is true even if the circuit develops a break (i.e. infinite resistance), in which case the entire EMF drop happens across the break.

Here is where I think your confusion originates. A set of points in an operating voltage regulator has resistance 0.1 Ohms, and a set of points in a non-functional -- even though new old stock, regulator that sat in its box for 50 years -- has a resistance of >20MOhms. However, there was a lot of time, and a lot of Ohms, between those two extremes. At the lower end of these extreme, when the regulator worked, the resistance of the contacts was low enough that they were not acting as a current limiter for the dynamo. Later, as the points oxidized, but well before they reached 20MOhm, the resistance rose to the point where it was greater than the sum of all the other resistances in the circuit, so the contacts increasingly took on the role of a current limiter. Because of this, it would have increasingly limited the total power (V x I) that could be extracted from the dynamo.

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Torch2] #444342
07/12/12 3:12 pm
07/12/12 3:12 pm
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In a nutshell, what have you got to lose by attempting adjusting? The initial response gave good basic directions, these can also be found in the clymer BSA A B M model book from the mid 1960's and will work just fine for other brit bikes of the period with a regulator. (Hardcover with a basic yellow background on the cover.)

Let's face it, would you rather keep blowing up those expensive electronic units at $100 a pop, or try and learn how to make an old part that was designed for adjustment keep on working? I too shun the electronic gizmos, and back when I did pre units had little problem adjusting a regulator. Gotta remember, these things were made when you didn't just throw it away.............Yes, sometimes they are beyond saving, but in the real world a good lot of them are worth the effort!

After all someone has got to save these things from F.A.D.E. (ing) away!!!!

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Deadstiffcatt] #444345
07/12/12 3:20 pm
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Originally Posted By: Deadstiffcatt
would you rather keep blowing up those expensive electronic units at $100 a pop, or try and learn how to make an old part that was designed for adjustment keep on working?
I agree completely with this. These units are quite robust. I suggest you completely ignore completely everything gREgg-K and I have written on the causes of a possible slow, long-term effect on the operation of the cutout circuit, and adjust your regulator as per the detailed instructions posted very early in this thread (assuming they were accurately copied from a Lucas instruction sheet).

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Torch2] #444444
07/13/12 3:45 am
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I have adjusted them before and assumed one coil was a cut-in voltage circuit and the other was a cut-out circuit, I did adjust them to a cut-in of 6.0 volts in and a cut-out of 7.0 volts,
I'll try doing it as per Pete's directions and see what happens.

Thanks everyone for your help.

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Torch2] #444463
07/13/12 7:10 am
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Ain't done yet............circa 1952 manual....







If all else fails, time to try a little sacrificial ritual to....



I hope this helps with a bit more understanding of the process you are attempting. Regarding oxidation, thanks for the input guys! It added a couple more bits of knowledge to my understanding of WHY these things would need adjusting, for without the why, sometimes it is hard to understand the need to do an adjustment in the first place. Cheers to all! Joe

Note: Author of this post has absolutely no idea of how these photos of this book were taken on a semi sunny day on the kitchen table, although it is believed that the cat leaped upon the table, rubbed against the camera and hit the on button, then cleverly flipped pages and operated the shutter button with flicks of her tail, completely oblivious to the fact that she was indeed taking photos..........

Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: Deadstiffcatt] #507935
09/26/13 10:01 am
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dear deadstiffcatt and all the rest. I'm shocked that an official Lucas document recommends using emery cloth on contacts. PhattBob might remember from his days at British Telecom that silicone and emery cloth were banned from the switch buildings. I'm aware of this( retired telephone test equipment designer).
Emery cloth is carborundum loaded, chemical formula SiC. the cloth leaves particles of SiC embedded on the contacts, but they look shiny and clean. Later on though, the intense temperature of the arc breaks down the SiC into SiO and C. SiO if you might remember is glass. The contacts will go open circuit and not even a diamond burnisher will remove it. Old mechanics manuals would say 'never use emery cloth on contacts", can't find my old Motors manual that said this. Bell Laboratories in USA researched this and published photos of contacts with black glass islands.
I just took apart my Lucas regulator 1958 model and found the same thing. In fact I'm probably the guilty party since I was last in there in 1978 before learning about emery cloth.
I was able to remove the glass by taking the contacts apart and grinding with a high speed dremel tool. brutal but effective. The proper tool for cleaning contacts is a diamond burnishing tool, a pencil shaped handle with a steel shim on one end, that is diamond loaded.
Now I'm looking for clearance specifications for the contacts, the regulator is a Lucas RB108 for 1958 triumph T110. Anyone have the specs?

Last edited by PetervB; 09/26/13 10:04 am. Reason: ask for specs
Re: Adjusting a Lucas 6 volt voltage regulator.... [Re: PetervB] #507996
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Peter,
You need to find a copy of BSA service sheet 804A.
It is for the RB107 but it is the same as RB108.


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