4TR regulator question

[Bakdraft007]

I needed to replace my 4TR regulator.

I bought the replacement from Rimmers. They supply what they say is a compatible replacement, however its a 4 pin one when the original is a 3 pin one. The diagram they supplied on their website did not match the device they supplied. I rang them to ask what was their reccomednadtion for the replacement. After 2 days multiple calls they so far have been unable to answer me. They say they have asked their suppliers themsleves do not know and are trying to find out.

I would like to fit it this weekend, so I am hoping one of you clever chaps may have fitted this one before

here is the one rimmer supplied:
IMG_1672.JPG

Looking on the internet there seems to be every variation possible made of these.

My understanding is this:
F - is F
- is - (- on the alternator which is ground)
+ is the + on the alernator and the main alternator output

The other none marked pin is most likely what is marked on others as B+ which would be for what was the later 4TR for battery sensing. I think the theory was the original tried to control the output of the alternator which is the + position. They realised on later models that this theory was flawed because of the volts drop along the length of the cable from the alternator to the battery. Meaning if your voltage was 14.4v at the alternator it would become 13.5 at the battery. So to fix this they took an unloaded cable from the battery directly to the regulator and connected to the B+ (battery +) pin. This then was the reference the regulator worked to rather than the alternator.

So of course my Mk1 does not have this battery sensing, so do I connect to the + pin assuming that this is still the correct point, or do I connect to the blank pin or does it not matter as in some photos I have seen they simply soldered the pins together anyway... this would seem to be born out with my multi meter as it seems to show they may be soldered.

Has anyone out there fitted one the same as in the photo and which pin did they connect to etc.

If nobody replies.... I will let you know what happens and if it goes bang..

Dave

[Phil S]

fit a later alternator with the internal regulator, leave the old unit in place if you want to look original, 1 wire from alternator to battery and the warning light light wire

[mallardstag]

This is from the Rimmer's web site...


If converting from 3 Terminal type connect as follows:

M12.jpg

See https://rimmerbros.com/Item--i-BHA4789

Also more useful info here...

https://www.mgexp.com/forum/original-mg-forum.71/lucas-37527-37586-4tr-alternator-control.3030822/

[Bakdraft007]

This is from the Rimmer's web site...


If converting from 3 Terminal type connect as follows:

M12.jpg

See https://rimmerbros.com/Item--i-BHA4789

Also more useful info here...

https://www.mgexp.com/forum/original-mg-forum.71/lucas-37527-37586-4tr-alternator-control.3030822/

The problem is that diagram does not match what rimmer supply and they agree... They cannot get their supplier to tell them exactly what the correct connection should be...

[Bakdraft007]

This is from the Rimmer's web site...


If converting from 3 Terminal type connect as follows:

M12.jpg

See https://rimmerbros.com/Item--i-BHA4789

Also more useful info here...

https://www.mgexp.com/forum/original-mg-forum.71/lucas-37527-37586-4tr-alternator-control.3030822/

In many ways this was still useful

Looking at the 4TR diagram below:

4TR Circuit Diagram.png

Clearly the rimmers diagram suggests the '- goes to -' and 'F to F'.. no problem

They say + goes to B+ (Battery sense or Battey +) Yet it could never work unless + is connected to the alternator output, as + supplies the field power to control the alternators output. So internally B+ is joined to + to provide the power, ( which is what I can see with my multimeter.) It is also what I have seen in other diagrams of the inside of a 4TR see below.

4TR PCB.png
As you can see the left two pins are joined..

So in esscence, it does not matter which pins you connect to ( + , B+, or in this case no marking) the effect is the same as they are internally joined.

So in summary, they turned a Battery sensing device into a machine sensing device .... or at least thats what I am assuming.

[Bakdraft007]

In many ways this was still useful

Looking at the 4TR diagram below:

4TR Circuit Diagram.png

Clearly the rimmers diagram suggests the '- goes to -' and 'F to F'.. no problem

They say + goes to B+ (Battery sense or Battey +) Yet it could never work unless + is connected to the alternator output, as + supplies the field power to control the alternators output. So internally B+ is joined to + to provide the power, ( which is what I can see with my multimeter.) It is also what I have seen in other diagrams of the inside of a 4TR see below.


As you can see the left two pins are joined..

So in esscence, it does not matter which pins you connect to ( + , B+, or in this case no marking) the effect is the same as they are internally joined.

So in summary, they turned a Battery sensing device into a machine sensing device .... or at least thats what I am assuming.

Well that was interesting... When connecting the + wire to the bkank pin... no output.. When connected to the + pin it worked as before... only as before was not what I wanted. I am still stuck going up to 15V

Still at least I can say its not the reulator, although I at this time I do not know what it is... the story continues....

[StagJonno]

Never had a faulty external regulator but it occurs to ask what condition is your battery? If it's knackered with a high internal resistance, there may not be any significant charge current which may impact the apparent regulation..

[Bakdraft007]

Never had a faulty external regulator but it occurs to ask what condition is your battery? If it's knackered with a high internal resistance, there may not be any significant charge current which may impact the apparent regulation..

The xisiting battery was of unknown origin (although it seemed ok) So I fitted a brand new Yuasa battery... no change .. so not battery. I guess I really need someone with an early Mk1 11AC to let me know exactly how good regulation really is. My regulator seems to be a bit random.... sometimes ruuning up from 13.5 to 14.9v other times seeming happy to be at 15v... then back down again.

The old 4TR and new one both the same as each other. Both old and new are supposidely compatible 4 pin, but not original 3 pin.

[DJT]

Have you checked the alternator control relay? This is the box mounted at the top of the suspension turret. Full instructions are in the ROM.

[Bakdraft007]

Have you checked the alternator control relay? This is the box mounted at the top of the suspension turret. Full instructions are in the ROM.

Yes, that seems to be working fine. It cuts the alternator out somewhere around 13.2v. I am starting to think that perhaps my expectations of the regulator are too high. its says it operates between 13.9 to 14.4v. and in general the average is maybe not far from that. Yet it definitely runs around 15v at times. Theis matches my multimeter and battry monitor... they agree with each other exactly.

IMG_1682.JPG

I just noticed that alternator test at the bottom.. I must try that...

[Bakdraft007]

Here is the Alternator test
IMG_1685.JPG

Hmmm same thing... I am thinking I might just have to get an original 3 pin regulator to be sure...

[Bakdraft007]

OMG! I can't believe it...

I ordered a Genuine new old stock Lucas 3 Pin 4TR from ebay at great cost (£59) and fitted it resigned to the fact that it was more money down the drain, only to find IT FIXED IT

The difference was massive:

1. It now runs 14.1v to 14.4v and never higher
2. Its now smoother in its delivery
3. But most incredibly it fixed my alternator light

Before this, when the engine went back to tickover, the alternator light would start to glow. This was pretty consistent. Also, the alternator output at tickover would plummit down. Now I have a constant steady 14v and, of course, the alternator light is perfect.

The one I bought from Rimmers shown in the photo is going back and they were happy to refund. I have told them my story, but wether they do anything about changing to a real 3 pin or find out why the 4 pin does not work will be up to them, but I am letting you know.

In the photos below, you can see the 4 pin supplied by Rimmers as supposedly compatible, and the NOS 3 Pin with its box.

Also is the trace from the alternator tracker..

It was worth all the agro as I have just fitted a new 030 Yuasa battery and I didn't want it cooked.

IMG_1698.JPG

IMG_1699.JPG
IMG_1701.JPG

[DZP]

That new voltage regulator seems to be working really well, but looking at the circuit diagram for the 4pin version it should work OK with B+ & + connected together.
However, voltage regulation is totally dependent on the breakdown voltage of zener diode (VR) and B+ must be connected.
With normal voltage (say less than 14.4v) then there is 0v between VR & C1/C2, T1 is off, T2 is on, T3 is on, Field (F) is excited voltage rises.
Over-voltage (say >14.4v) then VR breaks down voltage between VR & C1/C2 rises, T1 is on, T2 is off, T3 is off, Field (F) is off, voltage drops.
C2 charges/discharges to smooth the whole switching process.
If B+ is not connected, then there is no voltage regulation and the battery gets cooked.

[Bakdraft007]

That new voltage regulator seems to be working really well, but looking at the circuit diagram for the 4pin version it should work OK with B+ & + connected together.
However, voltage regulation is totally dependent on the breakdown voltage of zener diode (VR) and B+ must be connected.
With normal voltage (say less than 14.4v) then there is 0v between VR & C1/C2, T1 is off, T2 is on, T3 is on, Field (F) is excited voltage rises.
Over-voltage (say >14.4v) then VR breaks down voltage between VR & C1/C2 rises, T1 is on, T2 is off, T3 is off, Field (F) is off, voltage drops.
C2 charges/discharges to smooth the whole switching process.
If B+ is not connected, then there is no voltage regulation and the battery gets cooked.

I did indeed try connecting B+ & + together. Initially it did seem better, but then in reality it was just the same. I am not sure what the real situation is as there are many variations of the 4tr.

What was very evident is that the true original 3 pin absolutley worked perfectly.

The 4 pin must have been reaking havoc with not only the battery but also the 16RA. It was cutting in and out all over the place. I find it curious that what was fitted was a 4 pin, not working well, the new Rimmers was a 4 pin not working well. I wonder how many Stags there are out there with dodgy regulators..

[StagJonno]

It's also possible that the one you got from the Brothers was faulty - possibly a dry joint between the 2 x B+ terminals. I've met a few folk who've replaced their alternators for one with an inbuilt regulator (often with higher outputs) - some retaining the separate regulator (disconnected) just for show.