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MG MGA - Charging problem

Hi, A couple of weeks ago I cleaned the contacts on the control box as I have never done this. Coming home from a drive days later I notice the ignition light was on, when I got home I checked the connections on the dynamo they were good. Next day I checked the voltage output of the dynamo by removing the D and F leads and then linking these at the dynamo, connected volt meter from D or F terminal started car and got about 3 volts, should have been at least 12v. Had the dynamo reconditioned, put it back on the car did the same test and easily got 12 - 20v at low revs, but red light still on voltage on dash battery condition gauge only showed battery voltage about 12.5v. Must be a duff control box, got new one from Moss, fitted it same problem. Checked wiring from dynamo to control box by removing the D and F wires at the control box joining them together and connecting digital volt meter from them and earth, with engine running I got 12 - 20v. Dynamo was polarised to positive earth before testing. Any suggestions what else can I do?

Many thanks

Dave Swinburne
Kent UK
MGA 1500
Dave Swinburne

Another test was to disconnect battery via isolation switch with engine running when this was done engine died.
Dave Swinburne

http://mgaguru.com/mgtech/books/pdf/Lucas_Generator_and_Control_Box_Tests.pdf

Just follow the tests sequentially, it's very logical and simple to do
Dominic Clancy

If you need new bits try - http://www.dynamoregulatorconversions.com/whats-new.php
Nigel Atkins

Better for a new regulator is AES as they have a guy who restores and calibrates the originals.

The modern repros are junk, just had to replace one on a midget because the spade contact was badly riveted to the body. I could have repaired it but as I had a spare in the cellar and I am trying to slim down the inventory....

Dominic Clancy

Classic Dynamo & Regulator Conversions don't do modern repro junk - dead opposite.

"Advanced Dynamo Regulators is CDRC Ltd's own brand of electronic dynamo regulator.
We make them right here in the UK.
Why Advanced? Well, because our ADR range is by far the best and most reliable regulator available".

Peter is an individual, you'll get the jist from his 'About us' page, he may say something like modern repro junk but I bet he's thinking of a less flattering description.

I've dealt with AES and they were fine but Peter of CDRC is at a different (higher) level.

http://www.dynamoregulatorconversions.com/about-me.php
Nigel Atkins

Many thanks for the info, the original problem was a duff dynamo which was fixed with new brushes and a good clean. As for the regulator the new one from Moss with much fiddling and testing it now works charging at 14v doing 3000rpm. But I have no confidence in it and will look into getting a refurbed original.
Best regards
Dave
Dave Swinburne

This thread was discussed between 19/07/2019 and 20/07/2019

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