andy1960 Posted August 13, 2016 Share Posted August 13, 2016 Hi All. My Bedford MWD seems to have poor charging. Symptoms are ...switch on and red warning light glows, ammeter shows 9 amp discharge.Start engine, red light goes out and discharge drops to about 5 amps....rev engine and discharge drops to 1 amp but will not go over zero or anywhere towards a charging reading. Thoughts and suggestions please....:embarrassed: Quote Link to comment Share on other sites More sharing options...
Tony B Posted August 13, 2016 Share Posted August 13, 2016 The 3B's of a dynamo. Belt, brushes and bearings. Loose or dirty fittings check earth as a matter of course, then onto the regulator box. Quote Link to comment Share on other sites More sharing options...
Degsy Posted August 13, 2016 Share Posted August 13, 2016 Or it could be just a faulty ammeter. Quote Link to comment Share on other sites More sharing options...
andy1960 Posted August 13, 2016 Author Share Posted August 13, 2016 The 3B's of a dynamo. Belt, brushes and bearings. Loose or dirty fittings check earth as a matter of course, then onto the regulator box. The three Bs seem ok. How do I test the regulator box please? Quote Link to comment Share on other sites More sharing options...
Tony B Posted August 14, 2016 Share Posted August 14, 2016 Found this site that gives nice clear instructions http://www.howacarworks.com/electrical-systems/testing-a-dynamo-and-checking-output One other quick check that would be worth trying is to repoloraise the Dynamo. BUT, VERY MUCH BUT, disconnect the regulator BEFORE re poloraising. http://www.dynamoregulatorconversions.com/polarising-a-dynamo.php Quote Link to comment Share on other sites More sharing options...
andy1960 Posted August 14, 2016 Author Share Posted August 14, 2016 Found this site that gives nice clear instructions http://www.howacarworks.com/electrical-systems/testing-a-dynamo-and-checking-output One other quick check that would be worth trying is to repoloraise the Dynamo. BUT, VERY MUCH BUT, disconnect the regulator BEFORE re poloraising. http://www.dynamoregulatorconversions.com/polarising-a-dynamo.php Thanks Tony B...a great help! Regards Andy B Quote Link to comment Share on other sites More sharing options...
Tony B Posted August 14, 2016 Share Posted August 14, 2016 Thinking again, (It's the age you know) Though the brushes may look OK, worth taking the back off and checking the springs that push the brushes in to the commutator, they can stick. Clean the copper bands, don't us an abrasive that can clog the gaps and cause shorts, also check the end of the brushes haven't worn in a curve as that can make only a small contact area. Not a lot to go wrong on a Dynamo, the last one I know that failed had a bearing collapse in about 2005. Though the bearing was dated 1945. Quote Link to comment Share on other sites More sharing options...
andy1960 Posted August 20, 2016 Author Share Posted August 20, 2016 SORTED... 5amps charging now. Hidden break in the wiring! Thanks for the advice .. Quote Link to comment Share on other sites More sharing options...
Tony B Posted August 21, 2016 Share Posted August 21, 2016 No problem. Quote Link to comment Share on other sites More sharing options...
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