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MG MGA - Voltage Regulator Help

Hi All,
I am hoping for advice with a charging problem. I have a 1959 MGA 1500 and replaced the generator about 300 miles ago. I was advised to also replace the control box (regulator) and did so with a Moss unit. Now the charging voltage varies with engine RPM quite dramatically and will hit over 17 volts at 3000RPM. It is OK at about 14 volts at idle. I can't believe this is normal and unfortunately chucked my 40+ year-old regulator which had given yeoman's service. Is it worth fiddling with the adjustment on this unit, or time for a new one?
Thanks
Tom Heath

Pity you chucked the old one Tom, the old ones seem to last forever. I don't chuck anything, but my garage looks like a rubbish dump!
17 volts is too high, could be caused by the regulator contacts welded together, not enough tension on the regulator return spring (adjustable) or a disconnection in the regulator coil (causing non-operation of the regulator "relay". Is it still under guarantee? Adjustment of the regulator is described in the manual and on Barney's web site I believe. Adjust the screw very delicately, a little bit of a turn makes a big difference. If the coil has gone disconnect, you may have to throw another regulator away unless you can see and repair the disconnection.
Lindsay Sampford

Definitely makes sense to mess around with the adjustment of the regulator.
It is a bit fiddly but it does work.

I would recommend following the instructions on the Lucas Generators and Control Box Tests.
http://mgaguru.com/mgtech/books/books_3.htm

I found it was more detailed and complete than the description on the workshop manual.

Good luck!
Gonzalo Ramos

Tom - The regulator is definitely not doing its job. I would suggest that you not drive the car until the problem is rectified as you will destroy the battery and quite possibly the generator. You can send the regulator to Wilton Auto Electric (Bob Jeffers) where they can convert the regulator to solid state at a reasonable price. There web site is: http://wiltonae.com/home/index.aspx At the very least, e-mail Bob at the address given in the above web site. He can direct you as to how to possibly fix the regulator. Cheers - Dave
David DuBois

Return it to Moss. They have a decent return record.
Sandy
SANDY SANDERS

Thanks to all for their input. I will try to adjust the existing unit first. I am reluctant to try Moss for a replacement since those 300 miles likely took 2 or 3 years to complete! A new one will be in order if I can't fix it, I guess.
Regards,
Tom
Tom Heath

I have a couple of OEM voltage regulators - and I'm sure most people on this list have one banging around in their piles of parts. Let me know if you need it and it's in the mail.

JIM in NH

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This thread was discussed between 19/08/2010 and 20/08/2010

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