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MG TD TF 1500 - Alternator conversion - Wiring

Good Afternoon.

I am upgrading to a alternator "Dyanator". I am not skilled in electrics and would like to know how to modify the 9 post wiring at the regulator.

I have tracked down a wiring diagram for a 5 post regulator block - but not a 9

The enclosed photo shows my regulator wiring and if possible I would like it to look mostly the same after the modification.

I assume I could "jumper" the relevant terminal posts together not so?

The terminals are labelled from left A1 A A2 F D A4 A4 E A3


If I do jumper them - how do I disable the internals of the regulator so it stops doing whatever it does.

Finally - will the existing fuses on the regulator block still be in circuit or do I need additional protection?

I would appreciate any response to be in a language so simple that even an electrical idiot like me can grasp it!

Thank you

Doctor Bob

Doctor Bob

Hi Bob,

You will find a wiring diagram for a 9 post TD on line. The alternator doesn't need any of the internals of the regulator - simply a heavy duty wire from the alternator directly to the ammeter and then to the battery. This needs a 'T' connection, before the ammeter to provide power to the loom. There is also a thin wire from the alternator to the warning lamp. The power feed to the loom connects to the two fuses which in your case are in the regulator. One fuse is controlled by the ignition switch and the other is always live. My TF has a 5 post regulator with an external fuse box. Because these regulators are common and inexpensive (unlike your very costly one) I ditched all the 'insides' and have secreted fuses protecting other circuits under the cover. Considering the cost of a 9 post regulator I would carefully cut the wiring to the coils etc so that they could be resoldered if required.

Re the alternator you have purchased I bought an expensive one from Moss c 350 It had a machined turned aluminium case. After four of them failed Moss returned my money and paid for all carriage costs. The problem was absolutely nothing to with Moss who provided exemplary service. A very reputable firm of auto electricians in Glasgow believed that an off the shelf Denso alternator had been fitted into a solid case. The original Denso case was littered with cooling slots and my converted unit was overheating. I understand the cheaper, plastic case alternators are designed from scratch and do not have this problem. Eventually I opted for "if you have got it flaunt it" and have fitted a standard alternator from a Renault Clio. Despite its small size it can push out over 50A - hence my rewire? I will post a photo of the Clio alternator separately.

Cheers

Jan

J Targosz

Hi Bob,

PIC of the Clio alternator fitted to the TF. I needed a small unit because of TF's tapering bonnet but I suspect a standard one would fit in a TD


Jan

J Targosz

Thanks Jan

I do have the wiring diagram - it's in the workshop manual.

What I don't know is what I need to connect to what now I have an alternator.

Do you know?

Regards
Doctor Bob

Hopefully you can read this...if no, email me and I'll send a photo of it to you.

Gene Gillam

I think that Jan means the wiring diagram that came with your alternator. Not the one in the WSM. Bud
Bud Krueger

Rip the guts out of the regulator, leaving just the terminals. Then get some heavy gauge copper wire and wire in a fuse holder and 45amp fuse inside the regulator. Connect as per the instructions that came with the Dynamator. Run a 50amp plus cable to the battery, either via the ammeter or preferably direct. The ammeter is rated at less than 45amps, but as long as your battery is in good condition it will never see anything like that. I fitted a Dynamator this way and its working well. Even if you have fitted a thermostatic fan I would keep the mechanical fan as the continuous cooling may be beneficial to preventing the alternator overheating.
Dave H
Dave Hill

Hi Dave,

I did exactly as you recommend and ripped out the regulator internals but mine was a cheapo 5 post one. If it has been one of the rare and expensive 9 post ones I would have simply cut the rear connection to the terminals so the regulator could be reinstated if required.

Jan
J Targosz


Jan, Dave, Bud, Gene...thank you

...and yes Gene I could read the instructions....very much appreciate the picture of the instructions (my dynameter didn't come with any worth reading !)

Thank you Gentlemen I have all I need now



Doctor Bob

Bob, can you give us a short report how the unit works.
I understand from othe sources that the Ammeter is not longer needed,therefore the heavy wire should go direkt to the Battery. I'm not sure what the best way will be.

http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=thread&access=&subject=8&source=T&thread=2015091316405330676
GK Guenter

Look at the wiring diagram and replace the brown/ white to brown wire that runs via the ammeter with a heavier gauge brown wire, but leaving the ammeter out of circuit. You don't need to remove the existing wire, just disconnect it and insulate the ends. If you want something that will tell you the alternator is working and the battery is up to snuff, fit a voltmeter. Nowhere to put it on the dash so fit it underneath or under the bonnet and remember to check it now and then! Connect between a switched live terminal and earth.
Dave H
Dave Hill

Jan. I kept my old voltage regulator, but bought a dirt cheap S/H one with innards of unknown viability and converted that. My only concern about the Dynamator is availability of spares, should they be needed. It would be nice to know what might fit.
Dave H
Dave Hill

GK,

There is no need to gut the regulator (5 pin or 9 pin)...by following the instructions on the sheet above you bypass the regulating functions while leaving the ammeter in the circuit to monitor your alternator.

Gene
Gene Gillam

This thread was discussed between 13/09/2015 and 14/09/2015

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