Not charging - Fixed it

[SteveW]

Have replaced the rectifier and regulator as the wiring was burnt out to the rectifier. Have replaced them with the combined solid state unit.

The field coil measures 5 ohms which looks correct and there is battery volts on the white wire to the field coil.

The three yellow wires from the stator measure about 1.0 ohm each which im guessing is correct if you take into account the resistance in the leads of my multimeter. Each of the 3 yellow wires also measure opent circuit to ground.

When the bike idles, im getting around 0.65 volts ac across any 2 yellow wires which is nowhere near enough.

Any ideas? im guessing the stator coil is fried but there is no evidence of any damage to it.

[mike the bike]

You won't get any ac generated unless there's 12V across the excitor coil.  That's the one in the middle of the alternator.   The 12V is fed from the regulator.

[SteveW]

There is 12V on the field coil, I measured the white wire that feeds it, the 12V is good.

The field coil appears good as the resistance of it checks out and its also not shorted to ground.

[mike the bike]

Is there 12V across the coil.  ie. 0V one side, 12V the other. 

12V on one side only tells half the story.   If there's 12V across the coil and if it isn't open circuit,  then it should turn into a magnet,  which should then induce an alternating current in the field coils because of the wriggly iron thing bolted to the crankshaft spinning round.  Getting too technical now.   

[SteveW]

Is there 12V across the coil.  ie. 0V one side, 12V the other. 

12V on one side only tells half the story.   If there's 12V across the coil and if it isn't open circuit,  then it should turn into a magnet,  which should then induce an alternating current in the field coils because of the wriggly iron thing bolted to the crankshaft spinning round.  Getting too technical now.   

Thanks Mike, i'll double check tomorrow.

[Bryanj]

Or to put it another way you need 12v on the white wire and the green connected to earth

[BigAl (Alan)]

Or splice the white wire and place each end on a AVO meter (as image) if the coil is OK the reading would be around 2 amps (DC amps scale 1-10 amps)

[mike the bike]

I used to have an AVO 8 Mk5 like that.  I prefer my digital clamp meter for current measurements as there's no need to break into the circuit,

[SteveW]

Just fixed it.
Turns out the green wire from the field coil goes to the middle bottom on the 9 way connector.
But the mating half of the 9 way connector has the corresponding green wire fitted in the middle top.

Moved it back to where it should be and its all working.

Hopefully that is the last electrical bodge on this bike 

[mike the bike]

Well done.  It's sometimes not easy fault finding other people's bodges.

[SteveW]

Just hope the previous owner hasn't touched the brakes 

[Bryanj]

See 12v across the coil and it works! I have only every seen those coils not work when physically damaged in an accident, seem to be very robust