Dynamo issue

[BSA500]

Hi,
 Just after suggestions. Dynamo 12 volt from Priory mags charging well,DVR2 reg. On the way to work just stops charging. Dynamo still spinning all wires connected,bridged green/yellow wires got 0.12 volts??. Had some issue with dirty commutator but worked fine after cleaning.

[BSA500]

Just tried the dynamo again after cleaning the commutator and no joy. I miss read the meter before I am actually only seeing 0.01-0.02 volts which is of course nearly nothing but it is a definite movement on the meter. The dynamo also smelt of TCP ????? is that a sign of over heating. Before it failed the ammeter would easily move fully over into the charge portion with lights off was that too much?.

[trevinoz]

Check your field for continuity but it seems like a faulty armature.
What load have you been putting on the generator?
My experience with 12V conversions has been that they will put out plenty of Watts but get too hot in the process and throw solder if loaded too high.

[KiwiGF]

One test you can try is put some current through the field after disconnecting the reg. Then measure volts at armature, or better still power up a 12v bulb.

On mine this test proved field and armature were ok but brushes were duff and preventing the self generation side of things occuring.

new brushes and no more problems. Before thatI lost charging every 300 miles or so and had to clean wwhat looked like a clean communtator.to get charging back

[BSA500]

Check your field for continuity but it seems like a faulty armature.
What load have you been putting on the generator?
My experience with 12V conversions has been that they will put out plenty of Watts but get too hot in the process and throw solder if loaded too high.

Load wise nothing above the normal lights etc and seeing as its summer here I have not had the lights on 

[BSA500]

One test you can try is put some current through the field after disconnecting the reg. Then measure volts at armature, or better still power up a 12v bulb.

On mine this test proved field and armature were ok but brushes were duff and preventing the self generation side of things occuring.

new brushes and no more problems. Before thatI lost charging every 300 miles or so and had to clean wwhat looked like a clean communtator.to get charging back

Could you point me to anywhere that shows the connections to do these tests. I have the Dynamo off the bike at the moment and I did notice one brush was worn unevenly. I think I will post some pics etc. Prob the shims will fail again and the dynamo becomes a lesser problem-me, pessimist, never

[KiwiGF]

http://www.a7a10.net/BSA/lucasmain.htm has some info.

from memory both armature and field are both earthed to the casing, and the two terminals the other ends of each with F being for field, other A for armature?

so connect a 12v bulb across the casing and terminal A.

connect a battery across the casing and F terminal with a bulb in series to prevent too much current passing through the field.

spin the dynamo and the bulb connected across the armature should light up. If it does the chances are your dynamo is good...

it is possible to then take testing further "on the bench" and connect everything together including the regulator...much easier than fitting and removing the dynamo  few times!

[BSA500]

I found good article on the Matchless forum along similar lines. And some tests using a multimeter. There was no output(bar 0.02 volts) when run up with the two wires connected, so unless I am very lucky(ie brushes etc) she looks to be fubarred its just a case of which bit field/armature and of course why?? as it was producing a lovely charge quite high on the ammeter(was that an omen). Before it went dead on me I was running along at 60 with the lights on,again, did that push it to far??. Of course that shouldn't break it but does that indicate an issue with the DVR2 reg or battery.
Somedays I wish it could just leave me alone this constant queue of issues, I just want to ride the dam thing

[KiwiGF]

The test with 2 terminals joined assumes the residual magnetism and brushes are in good working order.. The test with a battery powered field doesnt so should give a better indication if your armature or field are stuffed.

just my opinion!

[duTch]

 Did you say if it's well earthed?

[BSA500]

Yes well earthed it has a nickel plated body as well no paint

[trevinoz]

Have you tried motoring it? This is not a test which is reliable as usually a crook generator will motor but not generate.
You could try driving it on the bench with a voltmeter connected to "D" and a battery feed to "F".
I have found that if the generator charges like this, the brushes have a high resistance between the rubbing face and the commutator.
In the past I have given the brush face a rub with abrasive paper between it and the comm and sorted the problem.
Your symptoms indicate the high resistance or an open circuited coil on the armature.