Dynamo query

Shajota

Shajota

Hero member
Location
Whitsundays Qld
Finally finished off reconnecting the wiring and setting up the Eagle so it was actually going before I embark on further tasks. Very pleased with how the wiring ended up with everything seemed to be working including all warning lights! It started easily, but had to make a few adjustments to get it running smoothly. Eventually took it for a spin around a couple of blocks and mechanically went pretty well. The gen light however would not go off and did not take long and I had a flat battery.
Did a search on here about checking the dynamo and polarizing it so went down that road first. Tried to see if it was working by putting a positive from a battery to (bridged) DF & D+ and negative to D-, however nothing! Took it all apart and brushes look fine (hardly any wear) and move against springs freely. Did a bit of a clean to armature and put all back together. Connected again to a battery and still nothing.
My understanding is that the dynamo should ?run? connected like that so I presume I have a problem in the Dynamo wiring and will need to take it to an auto electrician (bit hopeful trying to find one around here that will have a look)? Is there anything else I can do? Any advice welcome. 
 
Nat Magee said:
Did you check output with a voltmeter connected directly to the dynamo?
Click to expand...
No Nat, battery was flat when I got back, so while I was charging it I decided best to have a good look at Dynamo. Bike has obviously been sitting for a long time so presumed it would at least need polarising? When it didn't react to power connection I did as mentioned. Is my understanding incorrect and dynamo may be fine without working when connected as stated??
(I understand I also may have an issue with regulator, but was just checking this first)   
 
I?m at work now but have earlier posted a procedure for testing generator. Before you take it to a shop you can have a look and measure for continuity through the various bits. I had a broken wire between the windings once, very simple fix. If the gen light is wrongly connected (should be + to the globe and it ?earths? via the generator, it connects to one of the gen wires at the regulator), it will glow always and not allow charging. I had one touching earth once between globe and reg.
 
Peter,

Correct, your test procedure should have the dynamo running in the direction of engine drive, if polarized correctly.  If it remains dead, no charge can be expected.  Check the field windings for continuity, as Lee suggests.  Guess you'll need to disassemble it once again.  Checking the armature windings is a bit more difficult, but an old-school auto electrician should have the necessary apparatus.

If required, I can supply NOS field windings, field cores and the screws for attaching the cores to the housing.  The field windings are relatively easy to replace, just need a hydraulic press and a sturdy bar to assemble the whole caboodle properly.  If I'm not mistaken, NOS armatures are also available, would save the hassle of a re-wind.

piet.
 
Check all the basics very carefully. Just sitting shouldn?t cause it any problems, like needing to be polarized etc. You most likely have just a simple continuity issue, either to earth somewhere or an open circuit.
 
Tippie said:
Check all the basics very carefully. Just sitting shouldn?t cause it any problems, like needing to be polarized etc. You most likely have just a simple continuity issue, either to earth somewhere or an open circuit.
Click to expand...
Have just been trying to sort out testing of this and found the following. No continuity between armature stack and commutator, however virtually no resistance between commutator segments. Measuring between segments 180 degree apart  also show continuity. Presume from this the windings have shorted? Or hopefully there is a simpler explanation??
Your help is appreciated 
 
Tippie said:
Check all the basics very carefully. Just sitting shouldn?t cause it any problems, like needing to be polarized etc. You most likely have just a simple continuity issue, either to earth somewhere or an open circuit.
Click to expand...

Depends on how long it has been sitting.

Not much magnetism present to begin with, and this will decrease over time.  A little reminding jolt does no harm.

piet
 
Eureka, success.
The small digital multi meter I had been using was driving me mad so grabbed another one (read up a bit more about testing it) and tested the dynamo. This time it all appeared ok to me so reassembled. Took the regulator off and apart, rechecked all wiring and everything looked good and in fine condition (you can probably guess I aint got a clue ::))
Anyway, had another go at polarizing the dynamo and bingo this time it worked.
Reconnected it all and gen light went off as it should. Very pleased. Thanks for all advice on here including what can be found with the search function ;)
 
Well done, Peter. (bigthumb)

These things rarely fail, they are extremely robust.  A general clean-out every decade or 2 should see it working till eternity!  Long stand-stills (and owners that don't know what they think they know [quote Keith] :D) are probably their worst enemy.

piet
 
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