O

OldV8

Member
Hi,
I have a 1970 Series IIA, 2 1/4L Petrol. It is from that transitional period where they were switching from dynamo to alternator, and I have the original Lucas 11AC alternator (which LR borrowed for a short while from Triumph Stag, Jaguar etc, before adopting the 16ACR with integral regulator). There is a separate relay, and a voltage regulator in the charging circuit.

The regulator has lost it's cover, and the model number along with it! Photo attached. It doesn't look like any Lucas regulator model I can find.

Does anyone know which voltage regulator it is, and whether it is the original one? I would like to put it back to it's original configuration, if possible. And I need to change it due to the lack of a cover anyway, even if it is working (might be an alternator fault that has stopped the charging).

Any thoughts much appreciated.

upload_2020-2-5_15-35-23.png
 
rob1miles said:
I would expect to find a Lucas 4TR regulator for that period. Are you sure its a regulator? Could it be a reverse current cutout?
http://worldphaco.com/uploads/HISTORICAL_LUCAS_ALTERNATOR_REGULATOR.pdf
Click to expand...
Hi rob1miles,
Thanks for your thoughts, and for the link.
I think it is a regulator, although adimittedly, it is odd that it has only one coil. Other Lucas models do have a voltage regulator bobbin, and one next to it that is a cutout. The yellow wire in the photo leads to a contact (not very clear as it is obscured by the armature), which the voltage regulator would have, but not the cutout (I think!). There is a relay the alternator side of this 'regulator', which I think must do the cutout in this case. If it should be a 4TR, would that have a relay in the circuit as well?
I am uploading a photo of the relay too.
Thanks again.
upload_2020-2-5_21-38-24.png
 
Thinking out loud here: That looks more like a regualtor, If it is it should have wires to the brushes in the alternator (is anything written on it). The power comes from the stator windings but the regulation is done by varying the flow in the armature. I still think that relay is reverse current protection, it would cut in when the alterntor exceeded the battery and drop out when it went below, to stop the battery draining. Now days the diodes don't need one. To regulate it must eather cycle on and off fast or compress a pack of carbon disks, it doesn't look like either of those, and by 1970 Lucas were using solid state stuff so I don't see them using a relay to regulate.
 
Last time I saw an 11AC was on a 1968 Jaguar 420!
There's a circuit diagram on this site that looks like it's similar to your setup (NB the diagram is positive earth):

http://www.reizendemoke.be/techniek/manual/engielec/4.htm

You don't need a cut-out to prevent reverse current flow into the alternator as the rectifiers inside the alt do this automatically. But there is a 6RA relay used to isolate the field windings when the ignition is off, to prevent a small current from flowing back into the field.
The mystery device you have is likely to be an old-school electro-mechanical voltage regulator. It might be difficult to find a replacement, but as Rob said, you could use a 4TR in any case.
Where is the ignition warning light connected? All the 11AC diagrams I've seen use a 3AW warning light unit.
 
Interestng, I think that first picture is the field isolating relay and the second one is the regulator, the numbers of connections fit.
 
rob1miles said:
Thinking out loud here: That looks more like a regualtor, If it is it should have wires to the brushes in the alternator (is anything written on it). The power comes from the stator windings but the regulation is done by varying the flow in the armature. I still think that relay is reverse current protection, it would cut in when the alterntor exceeded the battery and drop out when it went below, to stop the battery draining. Now days the diodes don't need one. To regulate it must eather cycle on and off fast or compress a pack of carbon disks, it doesn't look like either of those, and by 1970 Lucas were using solid state stuff so I don't see them using a relay to regulate.
Click to expand...

Hi rob1miles,

Thanks for your further thoughts. After a bit more investigation I found the remains of a 4TR (a couple of small bolts, at the right spacing, with small remnants of bakelite attached, just above the location of the second photo). I have now got a 'new' 4TR - the early version with only 3 connections. It seems that someone had replaced the original 4TR with the electro-mechanical 'thing' in the first photo (and done some major revisions to the wiring!). I will have to try and unscramble.
 
ExMil109 said:
Last time I saw an 11AC was on a 1968 Jaguar 420!
There's a circuit diagram on this site that looks like it's similar to your setup (NB the diagram is positive earth):

http://www.reizendemoke.be/techniek/manual/engielec/4.htm

You don't need a cut-out to prevent reverse current flow into the alternator as the rectifiers inside the alt do this automatically. But there is a 6RA relay used to isolate the field windings when the ignition is off, to prevent a small current from flowing back into the field.
The mystery device you have is likely to be an old-school electro-mechanical voltage regulator. It might be difficult to find a replacement, but as Rob said, you could use a 4TR in any case.
Where is the ignition warning light connected? All the 11AC diagrams I've seen use a 3AW warning light unit.
Click to expand...

Hi Exmil109,
I seem to be one of the 'fortunate few' to have a Series 2A with an 11AC! LR workshop manuals I have don't refer to this brief departure on changing to alternator/-ve earth (although Autobooks mentions it briefly). The wiring diagram could be very useful in trying to put it back straight, so thanks for that. It is spaghetti at the moment! I will try and find out where the warning light comes from.
I now have a 4TR. And I did find a possible similar looking 6RA (what do you think?)

collect.asp
https://www.autoelectricalspares.co...5-33359-6ra-classic-relay-12v--20a-1913-p.asp
 
OldV8 said:
Hi Exmil109,
I seem to be one of the 'fortunate few' to have a Series 2A with an 11AC! LR workshop manuals I have don't refer to this brief departure on changing to alternator/-ve earth (although Autobooks mentions it briefly). The wiring diagram could be very useful in trying to put it back straight, so thanks for that. It is spaghetti at the moment! I will try and find out where the warning light comes from.
I now have a 4TR. And I did find a possible similar looking 6RA (what do you think?)

Image (in case the link doesn't work)

lucas-33157-33209-33213-33218-33250-33252-33293-33302-33315-33359-6ra-classic-relay-12v--20a.jpg
Click to expand...
 
Hi OldV8,
Your post reminded me that I also have the Autobooks manual (I prefer it to the Haynes for some jobs) and it does indeed refer to testing the field relay and also the 3AW warning light unit, although it doesn't have any wiring diagrams with either of those items! So I guess you have a rare setup from the period between the S2A dynamo and the S3 16ACR alternator.
Is your setup positive or negative earth?
The Lucas relay you found should be fine - the alternator field doesn't use a lot of current, so any 4-terminal relay would likely be ok and the Lucas one you found looks like the original.
The non-standard regulator you have looks like the kind fitted to some Japanese cars in the 1970s; presumably someone fitted that when the original 4TR died. Here's the unit from a 1970s Land Cruiser (I drove one of these briefly some years ago - anyone who complains about the fuel consumption on their petrol LR should try the 4-litre Toyota!)

Mech Reg.jpg
 
ExMil109 said:
Hi OldV8,
Your post reminded me that I also have the Autobooks manual (I prefer it to the Haynes for some jobs) and it does indeed refer to testing the field relay and also the 3AW warning light unit, although it doesn't have any wiring diagrams with either of those items! So I guess you have a rare setup from the period between the S2A dynamo and the S3 16ACR alternator.
Is your setup positive or negative earth?
The Lucas relay you found should be fine - the alternator field doesn't use a lot of current, so any 4-terminal relay would likely be ok and the Lucas one you found looks like the original.
The non-standard regulator you have looks like the kind fitted to some Japanese cars in the 1970s; presumably someone fitted that when the original 4TR died. Here's the unit from a 1970s Land Cruiser (I drove one of these briefly some years ago - anyone who complains about the fuel consumption on their petrol LR should try the 4-litre Toyota!)

View attachment 200064
Click to expand...
Hi ExMil109,

Thanks very much for your help with this. Much appreciated!
I think you are right about the regulator.
My setup is -ve earth.
It also seems to have a few idiosyncrasies! Most confusing one is that the alternator field (F +ve), negative of course on your wiring diagram, goes straight to W2 on the relay (ref attached diagram)!
There is no 3AW visible, or a feed to it, but I have a voltmeter in the dash showing the charging volts. (both voltmeter and ignition lamp work).

I drove an FJ45 100 miles to work every day (and back), on dirt roads, when I was in Australia. Never had a single problem. (petrol was cheap there back then though!).

lucas-33157-33209-33213-33218-33250-33252-33293-33302-33315-33359-6ra-classic-relay-12v--20a (2).jpg
 
Last edited:
Found this in my pile of "old but usefull" stuff. Dates from 1979: These seem the most relevant pages: (sorry some are upside down...)
001.jpg
002.jpg
003.jpg
004.jpg
 
Indeed "old but useful". It's interesting how much detail they provided in the workshop manuals back then - nowadays an alternator is treated as a black box to be replaced without doing much investigation...
Here's the diagram from Rob's manual (right way up :)). I think this is how your Landy would have been wired originally.
003.jpg


I'm not sure what all the wiring colours are - hopefully you have enough of the original loom to work them out.
It might be possible to do without the 3AW ignition warning unit (I recall they were temperamental even when new, so it's not surprising yours is missing) by connecting the light between ignition and the F terminal on the regulator. I don't think the 3AW is available now, although there do seem to be electronic alternatives.
 
Re the amount of detail, I think the expectation was that any self respecting owner would get their soldering iron out and fix it there and then. I also like the implication that to fix something you must understand the underlying science. I have a 1950s Jaguar "Drivers Handbook" not the overhaul manual, that includes resetting the cam timeing as though any driver should be expected to be able to do this.
Now come forward to the present day where fixing an alternator on a vehicle you own (on a battlefield!!) is not permitted by the manufacturer:
https://www.nytimes.com/2019/11/20/opinion/military-right-to-repair.html
 
Hi Exmil109 & rob1miles,

Thankyou both for your help with this. The level of detail, and the further understanding, really does help. I am getting to the point where I think I might be able to fix this, when it inevitably goes wrong, in some remote village in Uzbekistan (where I am planning to go on the way to Mongolia, in this Series 2a). Much better to practice in Cumbria, where I am at the moment, with some internet access!

It is becoming clear that Solihull were making things up as they went along, in this transition to Series 3! It turns out there is no permanent +ve feed from the battery to the relay (contrary to all the diagrams). There is an original splitter in the (ignition) switched +ve feed to the relay, in the original loom. And, as there seem to be no other options, I am rather forced to conclude that this originally fed both F+ via the relay, and the relay switching. Which begs the question - why have a relay, if there can't be power going to the field coil with the ignition switched off?

For interest, I attach a photo of the dash. The voltmeter is in the place of a charge warning light in earlier Series 2a configurations. It measures the voltage across the battery when the ignition is turned on, then the increased voltage when the engine (and alternator) is running. A clever idea from Solihull! But not shown in any circuit diagrams.

upload_2020-2-9_15-39-7.png
 
Hi rob1miles,

Hadn't seen that. Looks like they are having fun in their defender! Taking roughly my proposed route through Turkey and Armenia, to Azerbaijan and across the Caspian from Baku. There and back in 3 months in my case though - the maximum I can reasonably escape from work!

I am reversing my thought about using the same feed for the feild coil as operates the relay (ignition switched). Would create a loop to both sides of the ignition. Back to the drawing board! Can't work out how it worked originally, unless there was a loop back from the +ve side of the alternator stator (the only permanent +ve in the vacinity) - no sign of it in the original loom though.
 
I'm thinking about the two forms of exitation and wondering if this set up is a halfway house between a dynamo and an alterntor as we now know it. Call that contact in Uxbridge, they may be the world experts on old Lucas systems.
On your travel issue - my Series is converted to a camper - its an ongoing project but i may have solved a few problems that you have yet to face and all our solutions are low cost!
 
Family of 5 in a SWB for 9 months and 16000 miles, so perhaps you be wondering what to do with all the space?
 
Hi OldV8,
When I first looked at this circuit, I also wondered why they didn't just connect the field to the switched ignition feed. I think the reason is that any voltage drop through the ignition switch would then be seen by the regulator as a low output voltage and it would increase the alternator output, maybe overcharging the battery. Hence the relay to give as direct a path as possible to the regulator.
I guess it depends how far you want to keep it original (and it does appear to be a rare setup). And of course you want it to be reliable during your 3-month trip!
 
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