Dynamo charging problem

linearaudio · Post by **linearaudio** » Thu Mar 12, 2009 6:49 pm

Sorry its not a Moggy, but the question is related! A chap I know has an early E-type jag. He bought a new dynamo for it, but it was polarised -ve earth. He started it up, ammeter went haywire. Having realized his error he "flashed" the field winding to re-polarise it, but now it doesn't do anything. The regulator LOOKS OK, ie not burnt to a crisp.! Any ideas?

Post by **PSL184** » Thu Mar 12, 2009 7:08 pm

It shouldn't have hurt the dynamo - Is there any output from the dynamo or is he measuring it at the battery?

linearaudio · Post by **linearaudio** » Thu Mar 12, 2009 9:09 pm

That is what I need to find out! How do I excite the field winding to get an output from the charge terminal? It seems a bit extreme connecting it direct to "live", or is that OK?

Post by **PSL184** » Thu Mar 12, 2009 10:19 pm

Yes its OK, just power it directly and let it spin for a few secs and check it again - Keep going to you get an output. That is assuming there is no output at present from the dynamo? If there is output from dynamo but no charge at the battery then the reg is kippered....

Post by **bmcecosse** » Fri Mar 13, 2009 9:57 am

Yes - I used to direct feed the field for max output on my Rally Minor. Doesn't do the dynamo any good - but for a few minutes it will prove if it works or no. It can also be tested by running it as a motor. Does sound like the regulator has taken a beating.