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MG TD TF 1500 - Voltage regulator cut out/in

I'm having trouble with the charging system. The initial symptom was the ignition warning light remaining on (and getting brighter) as the engine revs increased. I have checked the generator, which is OK and the voltage regulator part of the regulator, also OK. However, the cut out/in contacts fail to close, regardless of the generator output voltage.

I have run through all of the tests in the Lucas manual for the regulator, but all its says in case the cut out contacts fail to close is to replace the unit. Has anyone else had this problem; is there no way to repair this?

Any help gratefully received!

Matt
Matt Davis

Matt,

Contact Bob Jeffers who is on this forum and is the recognized expert on regulators. His e-mail is;
bob@wiltonae.com

Regards,
Jim
James Neel

I should have added his web site:

http://www.wiltonae.com/home/index.aspx

Jim
James Neel

Ive now taken the regulator out. There is an article on MGA Guru which gives the measured resistance between the D and E terminals, which should be about 6 ohms. Mine measures 114 ohms. I suspect this indicates a break in one of the internal windings which would explain why the cut-in is failing to cut in. I've ordered a replacement from Moss, as they have a 20% off sale (in the UK) at the moment. I let you know if it solves the problem. Matt.
Matt Davis

Matt The 6 ohms you were looking for is the field resistance. You should see about 70 ohms from D to E. Since you are seeing about twice the correct amount the fine wire coil in the cutout is open.

You could replace the cutout relay with a diode. Keep the regulator relay.
Cheers,
Bob
Bob Jeffers

P.S. If you were closer I'd send you a cutout relay. I have quite a few, normally I just take them to the dump.
Cheers,
Bob
Bob Jeffers

Thank you for the information Bib. I've received the replacement unit from Moss. The resistance between D and E on the new unit is 45 ohms. The cover does not say "Lucas" on the top, but I'm going to swap this with the top with the original unit. Matt.
Matt Davis

matt, you should send your old unit to bob for an upgrade to electronic...totally invisible mod until you remove the regulator's cover. then you can resell the moss unit. regards, tom
tom peterson

Matt, I'm curious about the ignition light issue. The way I understand the system, regardless of the position of the cutout switch, the light should go out if the generator is producing voltage above that of the battery. This condition you describe seems like the light is grounded out allowing generator voltage through it.
Mike
Mike Hart (52 TD 16378)

Hi, Matt.

Needed a few things for the TD. Looking on the Moss site, I can't see the 20% off summer sale you mentioned. Is there a promotional code somewhere?

- Tom.
Tom Bennett - 53TD 24232

Mike - I think the ignition light will only go out when the generator is actually connected to the battery, via the cut out/cut in relay. Now i've fitted the new regulator everything is working as it should.

Tom - the 20% sale was only on for three days!

Matt
Matt Davis

Matt When that Moss replacement fails send your original to me for upgrade to solid-state. They don't seem to last 50 years like the originals did.
Cheers,
Bob
Bob Jeffers

Bob, I am having a Devil of a time with the TF. At least I know the ignition lamp works! Are you going to the GOF? If I don't have the car, I'll bring the Regulator.
-David
D. Sander

Dave S. See you there.
Cheers,
Bob
Bob Jeffers

This thread was discussed between 24/07/2011 and 03/08/2011

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