Joined: Sep 2017 Posts: 99 Threads: 31
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Location: Hampshire
I have just rebuilt a dynamo following realisation that the field winding solder joint had failed.
Everything seems to test OK (commutator segments, field winding resiatances etc.) and it runs as a motor. However in the car it fails to charge even after flashing it and reversing field windings.
Admit I am at a loss. Any bright suggestions?
Joined: Aug 2017 Posts: 1,257 Threads: 219
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Location: North Herts
Given my current (no pun intended) tribulations are you sure ammeter is being truthful?
Joined: Aug 2017 Posts: 177 Threads: 1
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To check that the dynamo is giving an output remove the leads from the D and F tags , then connect a link across DAnd F tags, take a 12 volt head lamp bulb, and connect it between the link and the dynamo earth. Start the engine slowly increase the revs if the bulb lights up brightly the dynamo is giving an output.
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
Not sure re what is meant by "reversing the field windings" but literally there is only one correct way. The tiny initial field current must reinforce the magmetism; if it counters will not start to generate whatever the polarity.
Joined: Oct 2017 Posts: 1,391 Threads: 44
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I've come across a few dynamos which motor but won't generate.
