Dynamo !!!!

[Tone]

Hi All, Had the A10 off the road for about a month to do various bits, one was to put on a new ammeter, when all together and started the ammeter was showing no charge I tried the test of joining the two wires from the dynamo and putting a meter on them and the body of the dynamo, didn't register any vaults! put the meter on the battery terminals shows the same when revved up! The dynamo was charging before, I've checked the wiring seems ok, the only thing I thought was strange was when I put the new ammeter on the same way as the one I took off wiring wise it went the other way so I had to swap the wires around, anyone got any ideas?

[LJ.]

Hi Tone... Dynamo might just need re flashing if bike has not been run for a month or more, give that a try.

[Tone]

How exactly do I do that?

[dpaddock]

Suspect an open connection within the ammeter.
If volts to ground on one ammeter terminal aren't the same as on the other terminal, the ammeter is faulty (unless they're both zero, in which case you need to swim back upstream until you find six volts to ground).

David

[manosound]

First, I saw Dave's post before sending out this one. Can't argue with Dave, but in case they help, here are my comments:

I can't say I know that the issue is not demagnetization, but it seems wierd to me. My dynamo sat for 25 years out of use and worked fine after a cleanup and new brushes. However, Lucas does describe the posibility of accidentally reversing the dynamo's polarity by incorrect connection. Here are the instructions for repolarization based on positive ground.

Richard L.

[cus]

Also, if a dynamo suddenly stops charging, always worth taking off the cap & kick the bike over
& check that it's spinning, if it isn't you may have snapped the chain behind the timing cover, the
chain can break & sit in the bottom of the case & you wouldn't know.... "worth a check"

Cus

[a10gf]

Do the lamp test, connecting directly to the dynamo's joined 2 wires (yellow+green), see this topic.
A 12v lamp should light up very brightly when you give some throttle. If so, your dynamo is ok.

For testing the Ampere meter, see the very scientific drawing below (6v lamp for 6v system, 12 for 12). Or, using a multimeter in ohm mode and measuring across the ampere meter connections, the reading should in practice show 0 ohm (very low resistance, close to short circuit).

Then check trough the wiring looking at the wiring diagram for your model.

[A10Boy]

You might find this useful.

http://www.youtube.com/watch?v=NV8FFgia7uU&feature=related

[Tone]

If you "flash" the dynamo, how do you know which polarity it's on?

[bsa- bill]

I might well need to do this in the following month/months, so here's my take on it and if I'm wrong more knowledgeable members will correct me and help us both Tone
i
It will be earthed to whichever side of the battery is earthed (usually positive in our case ) so will be flashed from the negative terminal thereby assuming positive earth polarity.

My mate up the road had this problem with a dynamo that had been refurbished and would not show any charge, it had been set up with the wrong polarity, he flashed it and cured the problem.

All the best - Bill

[A10Boy]

Bill you are correct.

When I bought my A10, it was on Neg earth and I wanted it as STD so I reversed the polarity.

I connected the battery, Pos earth, and flashed a wire from the Neg side to the field terminal and that was it polarity reversed.

Thats all you have to do Tone.

[Tone]

I tried the light test and I revved up slowlyish the light didn't come on until the revves were quite high, then the light came on and immediatly blew, is the dynamo knakered?

[bsa- bill]

Well the bulb is -  did you use a six volt bulb, unregulated the dynamo will generate nearer 12 volt.

I use an SRM belt conversion that increases dynamo revs by 10%, this helps at low revs

All the best - Bill

[a10gf]

If a 6v bulb was used and blew, that's a good sign ! Try again with a 12v, around 20+ watt. I suggest to check\clean the brushes, commutator and brush\connection plate, make sure the brushes are moving free under the springs.

[Tone]

Bill, I am running on 12v and have also a belt conversion from Hawkers,it's just it seems like it needed a lot of revves.

[a10gf]

12v, an important piece of information finally emerges  ... If you redo the test, try with a 24v, or trough 2x (similar) 12v lamps in series. AFAIR, should give signs of light from tickover, then intensity rising quickly as the revs rises.

[bsa- bill]

Hi Tone
 A10GF could have a point
All the best - Bill

[Tone]

How do I wire up 2x 12v in series, or is it easy to get a 24v bulb.

[a101960]

How do I wire up 2x 12v in series, or is it easy to get a 24v bulb.

Tone. A picture is worth a thousand words!

Connect 2 12volt lamps as shown in the rough (very rough) sketch. You connect +ve to -ve  +ve to -ve. Yes it would be easier to use a 24 volt lamp, however a 12 volt lamp should be just fine. As others have said if you were able to take the lamp out there is nothing much wrong with your dynamo. Next stop the regulator. If it is an electronic regulator they do not like reversed polarity.

[Tone]

sorry, on your sketch on the positive side is that two wires that go into the dynamo? I'm not sure because you say to take out the regulator and you wouldn't have to do that if the loom wires are out of the dynamo,or am I on the wrong track.