The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: KiwiGF on 11.03. 2019 06:10

Title: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 11.03. 2019 06:10
The field coil on my E3L dynamo is toast. I could buy a new aftermarket one for not too much, even with the freight to nz from the UK, but they look easy enough to make and I've got enough 0.7mm enamelled wire to do it.

There are a few old threads on this, and it has been done,  but I've not found too many details on how its done 'DIY" style. So some advice please.

Should I make a wooden former and wind onto that? Or is it ok to wrap it directly onto the core? (after taping the core up to insulate it).

Anyone got a pic of a suitable former?

Is it important to get the shape of the core right (eg slightly "bent" to match the casing diameter) or will it be bent anyway when the case screws are done up?

I've got some "Kapton" polyimide tape said to be good for 400 deg c, is that ok to use to hold the coil in shape? Its a bit thin but I could use several layers.

Any other tips on wrapping and winding the coil?

Title: Re: DIY Lucas E3L field coil rewind
Post by: Rex on 11.03. 2019 09:18
I would definitely make a wooden former, and keep dressing the corners in tightly too or you'll end up with a vague oval coil shape and less turns. Cut through the old coil to get an idea of how many turns Lucas used.
Title: Re: DIY Lucas E3L field coil rewind
Post by: morris on 11.03. 2019 20:32
Is it important to get the shape of the core right (eg slightly "bent" to match the casing diameter) or will it be bent anyway when the case screws are done up?
Can't help with the rest of your questions but the coils that are sold are always flat.
You pull them into shape by pushing the shoe and coil against the outer casing and tightening the screws.
I have made an expanding tool for that because pulling the coil up and insure that the shoe makes good contact with the casing won't work by just tightening the screws.
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 11.03. 2019 20:42
Kiwi, I made a former out of a plastic material that I had.
Made the two sides and drilled 1/4" holes in the four corners of the shape.
I made a 3/8" shaft with a thread on one end to mount the cheeks between two nuts with a suitable spacer between.
Then made up four 1/4" bolts with just enough thread to fit nuts and ensuring that there was only bare shank between the cheeks.
Also cut four slots in the mid of each side of the cheeks wide enough to slip a thin cable tie in.
If you are winding on a lathe you will need a counter.
First pull a length of wire through one of the slots and wrap around the shaft then wind the coil.
After winding, slip two cable ties through opposite sides and tighten enough to stop the coil falling apart.
Pull the former apart and remove the coil.
I wind a piece of polyester tape around the centre of each side to hold it together and cut off the ties.
I then bend the coil around a large diameter bar to give it some shape.
Attach the leads, insulate the connections with sleeving and tape coil.
I use 12mm cotton tape. I also paint the finished article with electrical varnish.
I will post pictures later.
The former I made is drilled to make E3l & E3H coils.
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 11.03. 2019 21:23
Is it important to get the shape of the core right (eg slightly "bent" to match the casing diameter) or will it be bent anyway when the case screws are done up?
Can't help with the rest of your questions but the coils that are sold are always flat.
You pull them into shape by pushing the shoe and coil against the outer casing and tightening the screws.
I have made an expanding tool for that because pulling the coil up and insure that the shoe makes good contact with the casing won't work by just tightening the screws.

Thanks, “bent” it is then! (Before it’s installed)
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 11.03. 2019 21:24
I would definitely make a wooden former, and keep dressing the corners in tightly too or you'll end up with a vague oval coil shape and less turns. Cut through the old coil to get an idea of how many turns Lucas used.

Thanks, your comment has made me realise trying to wind directly onto the  core is a non starter, what was I thinking!
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 11.03. 2019 21:33
Kiwi, I made a former out of a plastic material that I had.
Made the two sides and drilled 1/4" holes in the four corners of the shape.
I made a 3/8" shaft with a thread on one end to mount the cheeks between two nuts with a suitable spacer between.
Then made up four 1/4" bolts with just enough thread to fit nuts and ensuring that there was only bare shank between the cheeks.
Also cut four slots in the mid of each side of the cheeks wide enough to slip a thin cable tie in.
If you are winding on a lathe you will need a counter.
First pull a length of wire through one of the slots and wrap around the shaft then wind the coil.
After winding, slip two cable ties through opposite sides and tighten enough to stop the coil falling apart.
Pull the former apart and remove the coil.
I wind a piece of polyester tape around the centre of each side to hold it together and cut off the ties.
I then bend the coil around a large diameter bar to give it some shape.
Attach the leads, insulate the connections with sleeving and tape coil.
I use 12mm cotton tape. I also paint the finished article with electrical varnish.
I will post pictures later.
The former I made is drilled to make E3l & E3H coils.

That’s great, thanks for the info. It really helps a lot, I can just about fully understand how to make a former (cable tie tip in particular is “gold”) but if you can post up a pic that would make my day!

Out of interest I’ve got a spare E3N? (48w, short body) Dynamo, with a good field, and I was going to fit that temporarily, but then I noticed it has a b31 “gear” drive end, incompatible with the a10 sprocket drive arrangement. I didn’t realise there were different armatures.....other than length.
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 11.03. 2019 21:44
Your E3N is a bit of a bodgie.
It was originally a Matchless/AJS single generator with a tapered shaft.
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 12.03. 2019 00:25
Kiwi,
Pictures attached.
This one is for the field coils.
The shaft is actually 5/16" and this one has large windows in the sides rather than slots.
The nut on the end with the screw in it is the attachment for my counter.
There are 300 turns of 0.028" or 0.7mm wire.
When you are making the lead connections, the start of the coil will be on the inside of the coil. It needs to be taken up and across the end and run on the outside. Sleeve the conductor from the inside right up to the joint.
I use silicon insulated wire for the leads, I've found that PVC will go hard after a time.
The coil pictured is an original one reworked. I don't have any new ones to hand, I usually only wind 12V coils and to order.
Hope this helps, good luck.
Title: Re: DIY Lucas E3L field coil rewind
Post by: chaterlea25 on 12.03. 2019 12:45
Hi All,
Trevor, for information sakes can I ask how many turns and what gauge for a 12v field coil
What resistance should the could read?
I have a dynamo with new field coil but do not know if it's a 6 or 12v

Thanks
John
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 12.03. 2019 19:41
Kiwi,
Pictures attached.
This one is for the field coils.
The shaft is actually 5/16" and this one has large windows in the sides rather than slots.
The nut on the end with the screw in it is the attachment for my counter.
There are 300 turns of 0.028" or 0.7mm wire.
When you are making the lead connections, the start of the coil will be on the inside of the coil. It needs to be taken up and across the end and run on the outside. Sleeve the conductor from the inside right up to the joint.
I use silicon insulated wire for the leads, I've found that PVC will go hard after a time.
The coil pictured is an original one reworked. I don't have any new ones to hand, I usually only wind 12V coils and to order.
Hope this helps, good luck.

Thanks again Trevor, it helps a lot. I’ve almost finished my own former (pic Below) I’ve made it with 6mm corner bolts, drilled and placed to make a coil of inside dimensions 1 1/16” x 2 1/4”, and 5/8” thick (eg 5/8” spacer between plates).

I’m going to have to hunt around for some silicon insulated wire and sleeving  *conf* - its a bit of effort to do all this but it won’t be a “one off use” tool as Ive just measured my b31 field coils resistance, and it’s getting low so I’ll be winding a second coil (assuming the first works ok, but no reason why not eh).
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 12.03. 2019 20:53
Well done, Kiwi.
I use fibreglass sleeving over the wires, 1mm over the single wire and 3 or 4mm over the joints.
You may have to hunt around for polyester tape to hold the coil together and it is not cheap. You could probably get away with common cellulose tape, the original coils seem to have used something similar in many cases. Some use a paper type tape. Doesn't matter which as the outer binding will hold it all together.
When you start winding, make the first layer nice and even with the wires side by side, then it's open slather, just keep the wind as uniform as possible across the former.

John, the 12V field coil resistance could be anything, depending on the thoughts of the winder.
Originally I was making them 450 turns of 0.6mm wire giving a resistance of about 5.6 ohms.
I was not completely happy with this even though the generator would work just fine but I was concerned about the heating of the generator as flat out the field would be consuming 24 Watts against the 6V version consuming 12 Watts.
I was discussing this with Chris Zoch (Zochy's Magnetos) and he did a bit of playing with different gauges of wire and turns. He came up with 620 turns of 0.5mm giving a resistance of around 11.5 ohms.
We have both tried this with good results.
A bit long winded but I hope this helps.
Trevor. 
Title: Re: DIY Lucas E3L field coil rewind
Post by: chaterlea25 on 12.03. 2019 22:32
Hi Trevor,
Thanks for the info,
I have a couple of dynamo's to sort out (one of the days)

John
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 04.04. 2019 07:36
Some pics of progress, I’ve been a bit slack getting onto this but I now I have to get the bike on the road for a few hundred miles of a rally weekend mid April.

I’ve yet to work out to bend it, but the winding was much easier than I expected, the lathe turned at about a rev per sec, Ideally that would be slower for a novice  *whistle*

I found some high temp sleeved wire for making the thermals in an old motor, and I bought some “kapton” high temp tape for holding things together whilst I fit the terminal wires and bending.

I’m wondering if that sort of tape could be used to do the final covering? It’s thin but I could put a few layers on...
Title: Re: DIY Lucas E3L field coil rewind
Post by: chaterlea25 on 04.04. 2019 20:34
Hi Kiwi
Ask for some winding tape at a motor rewind shop
It was cotton I think originally, some sort of composite material nowadays
Usually soaked in insulating varnish once formed into place

John
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 04.04. 2019 20:59
Hi Kiwi
Ask for some winding tape at a motor rewind shop
It was cotton I think originally, some sort of composite material nowadays
Usually soaked in insulating varnish once formed into place

John

Excellent idea, but it will be a while before I will get to a town big enough to have a rewind shop (I live in a little rural town of 20,000). The kapton tape can (supposedly) take 400deg c and is very tough (doesn't tear like sellotape for example) I guess I was wondering if (tape) technology has moved on and there are better alternatives to what was used originally. It’s expensive (but not outrageously) so maybe that’s why it’s not used more  *dunno*. I bought it online as no shops around here had high temp tape of any sort.

I’m going to try bending the coil today, I think a bit of 1” pipe, angle iron (as a former) and a vice should do it  *work*
Title: Re: DIY Lucas E3L field coil rewind
Post by: chaterlea25 on 04.04. 2019 21:21
Hi Kiwi,
20,000 I would regard as a decent size town,
We must be better at burning out motors here as thinking about towns of similar size near here most have a rewind shop ????

John
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 04.04. 2019 21:30
Kiwi, I use cotton tape, 12mm.
I don't soak the coil in varnish but just paint it on, this saves the next bloke who has to refurbish the coil a lot of grief.
Originally the coils are not varnished.
As to bending, I just bend by hand around a piece of about 2" chrome bar, it doesn't take a lot of effort. If the coil is not too rigid it will take shape when pulled in with the pole shoe. This is why cotton tape is so useful, it allows movement.
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 05.04. 2019 08:07
Kiwi, I use cotton tape, 12mm.
I don't soak the coil in varnish but just paint it on, this saves the next bloke who has to refurbish the coil a lot of grief.
Originally the coils are not varnished.
As to bending, I just bend by hand around a piece of about 2" chrome bar, it doesn't take a lot of effort. If the coil is not too rigid it will take shape when pulled in with the pole shoe. This is why cotton tape is so useful, it allows movement.

Thanks Trevor, I must have wound it a bit tight as I could no way bend it by hand, it went a bit banana shaped in the vice, so I had to mess about with it a bit, but nothing major. It’s back together now.

Dumb question, I’ve got an original Lucas mechanical regulator which I calibrated for 6v some time ago. Will this work on 12v? if so, will it need recallibrating?

I’ve had 2 dvr2 fail with this dynamo, first after a fibre gear (it’s for a b31) let go, second after the main fuse blew when I accidentally shorted the horn feed, so I’m probably going to give a mech regulator a go, before splashing out on a third dvr2. I’ve been told if I fit a diode in the right place it stops the drain caused by mech regs at low revs. I’ll give that a go as I’ve got a diode of several Amps rating with no job to do.
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 05.04. 2019 23:38
Not a dumb question but the answer is no, the 6V reg will not be any good for 12V. The shunt coils wouldn't like the double voltage.
You could pull the reg apart and use the bobbins from a 12V car type regulator, the resistor will be a little low for 12V but shouldn't cause any grief.
The low output at low revs is a bit of a problem with 6V generators trying to put out 12V.
Better job with a rewound armature and field coil to suit.
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 06.04. 2019 01:53
Not a dumb question but the answer is no, the 6V reg will not be any good for 12V. The shunt coils wouldn't like the double voltage.
You could pull the reg apart and use the bobbins from a 12V car type regulator, the resistor will be a little low for 12V but shouldn't cause any grief.
The low output at low revs is a bit of a problem with 6V generators trying to put out 12V.
Better job with a rewound armature and field coil to suit.

Thanks again Trev, can I just use a 12v Lucas car type mech reg? I’m a member of the local vintage car club and I’m pretty sure there will plenty of those to choose from in their spare parts shed, for a small “donation”. The 12v battery is new and of lead acid type if that makes a difference, and when it needs replacing I’ll probably revert the bike back to 6v. My A10 is 6v with dvr2 and has given me no problems other the motobatt brand batteries only last a couple of years.
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 07.04. 2019 00:17
Kiwi, there should be plenty of the RB106 regs lying about, you probably know them, they have a Bakelite cover held on with a wire clip like the MCR1 & 2.
Same mech as the bike regs so just set the same.
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 07.04. 2019 01:59
Kiwi, there should be plenty of the RB106 regs lying about, you probably know them, they have a Bakelite cover held on with a wire clip like the MCR1 & 2.
Same mech as the bike regs so just set the same.

Thanks Trev, I’ll get hold of an rb106 if I can.

The new field coil works ok, at first it did not generate very well, and I found one brush had several ohms resistance, I guess from a poor contact between the copper lead and graphite, very odd!

It now motors ok on 12v and a few amps, but only gets up to 14 volts with f+d joined and spun by a drill, which is low but maybe the drill isn’t fast enough. With 2 amps put through the field and then spun by a drill it gives over 16 volts when charging a 12v battery.

Both my dud dvr2s will charge a battery but ONLY if the field is supplied current from another source, this indicates to me the faults are (just) on the field control side of the dvr2s. The side that allows current to pass from the armature to the battery (but not vice versa) is still working, but of course is unregulated.
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 07.04. 2019 02:05
Hi Kiwi,
20,000 I would regard as a decent size town,
We must be better at burning out motors here as thinking about towns of similar size near here most have a rewind shop ????

John

I’ll have another look! There is an auto electrical shop/workshop which has some NOS Lucas stuff, I was very surprised to find that (and one of the owners has a plunger a10)
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 09.04. 2019 02:20
Well after some crude testing I’ve bought a new 6v battery and 6v bulbs and reverted to the oem mechanical regulator by Lucas.

I’ll see how this goes but will probably get another dvr2 and run that at 6v.

What I found from my crude testing was that the field current was MUCH higher using a 12v battery than with 6v, and the revs have to be MUCH higher to get a net charge after deducting the current taken by the field.

So whilst I’ve can see the std 6v dynamo CAN be run at 12v I've formed the view (rightly or wrongly) it is not a good idea and will likely result in a fried field coil (or regulator) unless the dynamo is in first class condition, and not put under extra load eg from higher wattage bulbs etc.

Before this experimenting I had the view that the dynamo would not be under more “stress” when run at 12v as the (armature) current theoretically halves, but in fact, from my crude testing the armature (at 12v) is providing significantly more current to the field coil than at 6v (so the armature current doesn't halve in practice) and with the field coil taking quite a lot more current, it is o& course getting hotter and “wasting” some of the charging capacity.

I tried a diode in the circuit to stop “backwards” current drain at low rpm, it did not work as it prevented the dynamo from “self generating” the necessary start up voltage. On my bike the reverse  current drain only occurred on tickover, it charges on a fast tick over, so it’s unlikely to be a problem (especially in nz).

Lastly the mcr2 with its brass cover looks cool!



Title: Re: DIY Lucas E3L field coil rewind
Post by: Bsareg on 09.04. 2019 09:57
I agree that putting 12v through a coil designed for 6v is not going to end well. When I build my own 12v electronic regulators, I make sure that the field coil can never receive more than 6v. The disadvantage though is reduced  magnetic field and higher dynamo revs before achieving 12v output. That doesn't matter here in the sticks but can cause problems in towns and cities.
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 09.04. 2019 22:07
Another point is that doubling the current in the field coil results in quadrupling the power absorbed by the coil. Much more heat.
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 10.04. 2019 03:37
Me and the mcr2 are not getting on!

All is well for a few miles then it stops charging, I clean the regulator contacts (wet and dry 400 grit, then brake clean) and it starts charging again but only for another few miles. The cut out appears to be working ok, it’s adjusted so it does not cut out even at very low tickover.

Any ideas on what needs fixing?

Edit: just a thought, if the regulator contacts get dirty and don’t connect, does this result in “no charging” or just “reduced charging”? (Provided the cut out contacts are closed)

Also, I’m measuring the battery voltage when I say it’s developed a fault and is discharging, (eg gone below 6.4v, the no load voltage, even at high rpm) and as well as that the ammeter shows a discharge when the lights are switched on, at high rpm.
Title: Re: DIY Lucas E3L field coil rewind
Post by: BSA_54A10 on 10.04. 2019 09:29
You sound like you are falling for a newbie non-problem.
The dynamo is regullated.
If the battery is fully charged it does not generate so the ampmeter shows "0" until you do something that requires battery voltage.
If you want to test the regulator you need to be riding lights on when if all is well the needle will swing negative at idle then positive as you accelerate and drop back a bit after a few minutes when the battery has recovered from powering the headlights at idle.

My dynamo works perfectly and the amp meter reads 0 nearly all of the time
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 10.04. 2019 10:41
You sound like you are falling for a newbie non-problem.
The dynamo is regullated.
If the battery is fully charged it does not generate so the ampmeter shows "0" until you do something that requires battery voltage.
If you want to test the regulator you need to be riding lights on when if all is well the needle will swing negative at idle then positive as you accelerate and drop back a bit after a few minutes when the battery has recovered from powering the headlights at idle.

My dynamo works perfectly and the amp meter reads 0 nearly all of the time

Hi, that did occur to me BUT the battery is definitely discharging ALL the time when the fault occurs, but as you say the most obvious evidence of this is the ammeter showing (the same) high discharge at idle and high revs.

When it’s NOT got the fault the dynamo is able to keep the needle at 0 or showing charging at just a medium tickover, but this only lasts for a few miles (with the lights on) then the ammeter needle goes hard to the left when the fault occurs, and the only way I’ve found of getting it to charge again is clean the regulator contacts, but it may not be the contacts at fault but something is cooling down or *dunno*

The reg side contacts are sparking when the fault is NOT present, is that “normal” ? (they stop sparking when the fault occurs).
Title: Re: DIY Lucas E3L field coil rewind
Post by: Bsareg on 10.04. 2019 18:10
Sounds like you're losing the field current. If so and if the cutout contacts remains closed, there will be a large discharge through the armature. Look for an intermittent open circuit between the F on regulator and the F on dynamo. Usually a green wire.
Title: Re: DIY Lucas E3L field coil rewind
Post by: Swarfcut on 10.04. 2019 18:51
BSA Service Sheet  804 gives basic testing procedures and adjustment data for Lucas MCR 1 and MCR 2 Regulator Units. The regulator bobbin contact constantly vibrates to vary the field current, so under some circumstances  small sparks will occur between the regulator contacts.

 I would suspect the cut out is sticking. Stuck open, no charge to battery, no regulator sparking, discharge on ammeter with lights on. Stuck closed, works OK, but constant discharge  at low revs, below cut in voltage, and at rest, battery discharging through dynamo windings.
   First basic check is dynamo output, and integrity of wiring loom, looking for dry joints, split insulation, short circuits. Regulator terminals, clean and tightly connected into the regulator unit. A good spray with contact cleaner recommended and a continuity check between the terminal sockets and their corresponding circuit within the regulator cover.

 Swarfy.
Title: Re: DIY Lucas E3L field coil rewind
Post by: trevinoz on 10.04. 2019 22:32
Kiwi, you need to service the regulator as per the service sheet.
Maybe a good idea to remove the regulator armature and fixed contact and give them a birthday with a fine oil stone.
Do all of the adjustments with feeler gauges as per instructions.
Check continuity between "D" & "F". It should be close to 0 ohms.
Push in the reg armature and you should see at least 35 ohms, usually more and sometimes infinity, depending on the state of the resistor.
Check between "D" & "A". Should show an open circuit at rest and close to 0 with the armature pushed in. These contacts are silver and should be treated with care. Maybe a light dressing.
Next you have to adjust the regulator.
I do them on the bench with a generator.
First set the voltage on the regulator then set the cut-in voltage on the cut-out.
I then connect a battery and fine set the voltage.
Note that there are different MCR2s.
The early type come as either a 60W or 45W reg.
Identified by the number of heavy turns on the regulator bobbin.
5 for 60W, 7 for 45W.
The later type have the same mechanism as the RB107 & RB108.
Good luck, the first time is the worst, it becomes easy with practice.
If you have the late type mech, you need to look at the RB107 service sheet.
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 11.04. 2019 00:22
Thanks everyone, you've given me some ideas to get it working (especially Trevor). I have used the Lucas and bsa service sheets to set it up with feeler gauges etc (I did this a few years ago) but it’s got this annoyingly intermittent issue of stopping charging.

It might be just me but the service sheets say they are showing the “circuit diagram” of the regulator but I yet have to fully figure out what bits (eg coils, resistor, contacts) connect to what from the info given.

I’ve just achieved an improvement by cleaning the cut out contacts, Which I noticed will stay shut even when not conducting (eg if you put paper between them) and this stops the system charging, which is the symptoms I’ve got.

Oddly after cleaning the cut out I just went for a 15 mile ride and it stopped charging after 10 miles (according to the ammeter) but when I got home and stopped the engine, connected a voltmeter, restarted the engine and measured the battery volts it was charging again! (Also it was showing a charge on the ammeter).

The cut out contacts are ALWAYS closed when the engine is running. Open when not. I can not adjust them to open even at very low revs, but I’m assuming that is not causing the charging issue?

It’s good enough to take on the rally this weekend, and I’ll get onto fixing it next week (famous last words).

I also have a feeling the battery has a duff cell with a bit of resistance, it’s gets warm when charged by a charger, and i also suspect the ammeter is not always telling the truth! I’ll try the new 6v battery I just bought next week to rule that out as a issue. When it arrived I fitted that to my other bike (which has a dvr2) and the “old” battery in this one.

Edit: my reg has 5 turns on the reg bobbin (the pic I posted earlier by luck shows this so didn’t have go to the shed to check, it has an adjusting screw on the reg top contact, no need to bend anything to adjust it, so I guess it is a “late” 60w model)

Edit again: I’ve just found this circuit diagram and did a screenshot, it (only) makes sense to me if the “frame” is viewed as a common connection for the 5 wires connected to it (the frame sits at dynamo/armature output voltage), I also edited it where lines were “broken” (it must have been poorly scanned). It helps me to understand it if the “series” coils are just viewed as solid wires connecting “a to b” as they so thick they have very little resistance (unlike the shunt coils). The job the the series coils do (I thinkj is just relatively minor temp and battery condition compensation. The shunt coils actually close/open the 2 contact breakers.

I think the circuit diagram (probably) confirms that dodgy regulator bobbin contacts cannot (completely) prevent charging provided the resistor is ok (the F and D of the dynamo are always joined together directly, or via the resistor, but never not joined) also that if the cut out contacts close when the engine is running, then the dynamo is “flashed” ok and producing significant voltage/current, but if the cut out contacts are dodgy this can prevent the battery charging even when all else is ok.

As a test I will check if the dynamo will charge the battery with the lights off and the regulator contacts held apart with a piece of paper. This might rule out those contacts causing my issue of “no charging”.
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 11.04. 2019 08:14
Kiwi, you need to service the regulator as per the service sheet.
Maybe a good idea to remove the regulator armature and fixed contact and give them a birthday with a fine oil stone.
Do all of the adjustments with feeler gauges as per instructions.
Check continuity between "D" & "F". It should be close to 0 ohms.
Push in the reg armature and you should see at least 35 ohms, usually more and sometimes infinity, depending on the state of the resistor.
Check between "D" & "A". Should show an open circuit at rest and close to 0 with the armature pushed in. These contacts are silver and should be treated with care. Maybe a light dressing.
Next you have to adjust the regulator.
I do them on the bench with a generator.
First set the voltage on the regulator then set the cut-in voltage on the cut-out.
I then connect a battery and fine set the voltage.
Note that there are different MCR2s.
The early type come as either a 60W or 45W reg.
Identified by the number of heavy turns on the regulator bobbin.
5 for 60W, 7 for 45W.
The later type have the same mechanism as the RB107 & RB108.
Good luck, the first time is the worst, it becomes easy with practice.
If you have the late type mech, you need to look at the RB107 service sheet.

On D to F measured at the dynamo 1 ohm and 47 ohms (cleaning the contacts or “wobbling” them does not affect the lower figure.

On D to A zero ohms and open circuit, measured at reg. all good there.

Now I see the resistor is 47 ohms I’m wondering if this means the dynamo will not reach 6v if the reg contacts are dodgy) I guess it’s there just to keep some current going through the field at all times to reduce sparking at the breaker? I’m off on the rally early tomorrow so further tests will have to wait.
Title: Re: DIY Lucas E3L field coil rewind
Post by: Bsareg on 11.04. 2019 09:21
You're now on the right lines. To clarify a little, as you say, the the 47 ohm resistor allows the field to carry some current and so prevents a lot of arcing at the regulator points when they are vibrating. The thick series wire on the cut out coil is wound in the opposite direction to the inner coil. This speeds the collapse of the magnetic pull and frees the contacts earlier. That why when closing throttle the ampmeter will show a discharge for a moment before returning to zero. Temprature compensation is provided by the spring between the brass adjusting screw and the moving part of the coil. This spring is a bi-metalic strip that will (should ) adjust the output voltage to compensate for high temeratures. Keep going you'll get there soon !!
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 11.04. 2019 11:54
You're now on the right lines. To clarify a little, as you say, the the 47 ohm resistor allows the field to carry some current and so prevents a lot of arcing at the regulator points when they are vibrating. The thick series wire on the cut out coil is wound in the opposite direction to the inner coil. This speeds the collapse of the magnetic pull and frees the contacts earlier. That why when closing throttle the ampmeter will show a discharge for a moment before returning to zero. Temprature compensation is provided by the spring between the brass adjusting screw and the moving part of the coil. This spring is a bi-metalic strip that will (should ) adjust the output voltage to compensate for high temeratures. Keep going you'll get there soon !!

Thanks, yes I’m gradually getting there (finding a circuit diagram I mostly understand helps!). You’ve made me think, should the cut out points separate whilst the engine is running? Is it a major problem if they don’t? (Cos I don’t think mine do......)
Title: Re: DIY Lucas E3L field coil rewind
Post by: Bsareg on 11.04. 2019 14:18
The cut out points stay shut when charging. Just to clarify the cut points are the ones under the loop the regulator points are directly on top of the moving armature. If your cut out points are opening when running, it sounds like too much tension on the rear spring which is adjusted by the brass screw at the rear of main frame. Temerature increases the tension as the bi-metalic spring warms. This would make sense with your problem of charging stopping after a few miles
Title: Re: DIY Lucas E3L field coil rewind
Post by: Bsareg on 11.04. 2019 14:31
I should of added that accurate  adjustment of this screw is important. Though difficult without a variable power supply, what you're aiming for is the contacts to reliable close when the dynamo starts charging as the revs rise and reliable points separation when the revs drop to just above tickover. If you can get the two operations then you're  close enough. This adjustment does not effect charging voltage only cut in and out voltage.
Title: Re: DIY Lucas E3L field coil rewind
Post by: duTch on 11.04. 2019 15:53
 If it's any help, I found the information in this link a few years ago but from a different source (had to do some searching to find it);
 It's 1.8MB so too big to attach, so easier to download and save. I found it useful for a better understanding how MCR2 & RB107/8 work....

 https://www.fromtheframeup.com/uploads/Lucas05_Generator_Output_Control.pdf] [Search domain www.fromtheframeup.com/uploads/Lucas05_Generator_Output_Control.pdf] https://www.fromtheframeup.com/uploads/Lucas05_Generator_Output_Control.pdf (http://[Search domain www.fromtheframeup.com/uploads/Lucas05_Generator_Output_Control.pdf)

 But I can attach the guide I use for doing my reg., so have done so
 
Title: Re: DIY Lucas E3L field coil rewind
Post by: KiwiGF on 11.04. 2019 22:42
The cut out points stay shut when charging. Just to clarify the cut points are the ones under the loop the regulator points are directly on top of the moving armature. If your cut out points are opening when running, it sounds like too much tension on the rear spring which is adjusted by the brass screw at the rear of main frame. Temerature increases the tension as the bi-metalic spring warms. This would make sense with your problem of charging stopping after a few miles

I’ve got the opposite issue (I think) ....I cant adjust the cut out points to separate at low rpm, they only separate when the engine stops completely. I guess this means “bending” something or, as my question before, is it ok to have this situation even tho it may result in the battery discharging at very low  (Not3 by very low I mean with ignition retarded, as it slightly charges on a “normal tickover

I’m also thinking I might revisit the diode idea, next week when I’m back, but this time try placing it in the feed to the ammeter (not in the field/armature circuit).

Edit: I found time to bend the cut out “stop” downwards (reducing the points gap) and the cut out points now DO separate on very slow tickover (just over 6v with lights on). On normal tickover it’s (just) charging with the lights on at circa 6.5v, whereas I’ve heard they normally discharge on tickover, that might be cos I put a few extra turns on the field coil  *work*
Title: Re: DIY Lucas E3L field coil rewind
Post by: ironhead on 12.04. 2019 01:29
Just Thought I'd throw my 2 cents worth in here. I had the very same symptoms on another BSA ( B33) a while back.  Charged good with lights on for about 10-15 minutes then stopped charging. I went through all the settings etc etc . Even swapped generators - no difference. Finally gave in & fitted an electronic reg.  But when removing the bobbin assembly found a wire ( from vague memory the cutout bobbin) that was broken but still touching its terminal. I'll get back to trying to fix it properly one day but has been working faultlessly with the electronic one so far & as I use this bike every day, need lights.
Title: Re: DIY Lucas E3L field coil rewind
Post by: Bsareg on 12.04. 2019 09:08
Both part of the cut out points are adjustable by bending. First slacken the two screws holding the assembly together, press the armature (the moving part that carry one half the contacts ) until it lies flat on top of coil core, while holding tighten screws. This the correct position for the armature when energised. When tightning screws , make sure the two contacts line up. By bending the upper part, the upper contact should slightly bend the lower contact before it hits the core, this is to ensure good connection, there is also a slight sweep as they close to clean the surfaces. Now adjust the stop until there is a credit card thickness gap at the points when at rest. This is all rough and ready but will be within Lucas limits. Your field rewind (nice job) cannot cause battery drain on a correctly setup regulator. Athough lots of people run down MCR and RB reguators, they are more sophisticated and require more accurate assembly than many think. This scribble has taken longer to type than the job will take. Good luck 
Title: Re: DIY Lucas E3L field coil rewind
Post by: Bsareg on 12.04. 2019 09:54
Again I should have added, once the mechanical adjustments have been made, then check and adjust the cut in and drop out voltages and adjust using the brass screw with a spring (or locknut )  at the rear of unit.
Title: DIY Lucas E3L field coil rewind
Post by: Guy Wilson on 15.04. 2019 06:00
all of this has reminded me I've been running on a total loss lighting system for a few years now and really should get around to fixing it.. I'm currently running with a 12 volt 7amp hour UPS battery that needs charging every month or so depending on how much light I need. The brake light is my priority...
Guy
Title: Re: DIY Lucas E3L field coil rewind
Post by: muskrat on 15.04. 2019 07:21
G'day Guy.
I thought in your neck of the woods night riding requiring lights would be as dangerous as over here! Here we have roos, wombats and the occasional water buffalo. I'd hate to hit an elephant/hippo. LOL
Cheers
Title: DIY Lucas E3L field coil rewind
Post by: Guy Wilson on 15.04. 2019 07:42
Its more the drunks and and a lot of us driving on TV, marriage licenses etc rather than driving licenses, not to mention the bad roads, pot holes etc. Cows and goats are a bigger problem than elephants etc... unfortunately...

Title: DIY Lucas E3L field coil rewind RESOLVED
Post by: KiwiGF on 23.04. 2019 07:10
I went off on the rally and sure enough charging stopped after 10 mins or so. Luckily I did not need my lights during the weekend.

For some reason the regulator coils had got very hot and I assumed that was the cause of the lack of charge and removed it, but all seemed ok and the contacts opened when connected to a battery etc. A curve ball was that the 15amp fuse I'd fitted on the charging output (between regulator and ammeter) had blown but I eventually figured that out.

Once again cleaning the regulator points fixed the charging problem, so I took it apart and found the adjuster/point was different from a spare I had from a "parts" regulator I got with my basket case bike years ago. I am pretty sure the special metal "tip" had fallen off the adjuster/ point in the past  *problem*   - which is why the points became "burnt" and non conducting so quickly

I've swapped the duff adjuster for the good one and so far all is well  *beer*

I've attached a pic of the adjuster, and semi fried regulator...