Battery or earthing problem?

[wilko]

Frustrating! To avoid forking out dosh for a reco you must be systematic with these tests.A motoring dyno is not necessarily the only test of course but it's a good sign. You might have to have a growler test if it refuses to comply.

[Brian]

Its not looking good Hubie but just a quick run through to be sure.

1. You have confirmed the bike is positive earth.
2. You connected the positive terminal of a battery to the body of the gen and the negative terminal to the wire bridging the F and D terminals on the gen and it spun in the correct direction, anti clockwise looking at the drive end.
3. You connected a voltmeter to the gen, the positive lead (red) to the body and the negative lead to the wire bridging the F and D terminals and spun the gen in the correct direction with a drill or you put the chain on and started the bike and gave it a rev and it did not show any output. You had your voltmeter set on DC volts.

The fact that it motored would indicate that although the brushes are worn they are making contact with the commutater, it appears you have a faulty gen. It looks like you will need to get it profesionally tested and repaired. You can buy rebuild kits for these from the UK which gives you a new armature, field winding, brushes and bearings. I have just ordered one myself and they cost just under $200 landed here in Aus. You can of course get them rewound. It comes down to how confident you are at working on them as to wether you want to have a go at repairing it yourself or send it somewhere to get done.

Remember, a politician once told us "life wasnt meant to be easy"

[Hubie]

Thanks Brian,

Have done all that and I thought I had just had the thing rebuilt.  I am going down to Seaford tomorrow and a mate there is going to check it out for me.  Will see how it goes.  On the sprocket front, my speedo was somewhat innacurate, does 60mph quite easily and is not revving hard at all.

Cheers,

Dave.

[Hubie]

Okay,

the dynamo is off the bike, it runs as a motor when power is put to it, and it does not matter which way you connect it it still runs in the same direction (which is the correct direction according to the arrow on the dyno - and is clockwise from the drive side).  When I put a power source to it and run it (slowly) it produces a reading (5 volts) across the brush terminals.  When I use a drill to run the dyno (again in the correct direction) I get .2 volts tops.

If I had hair, it would have well and truly have been pulled out by now!

Cheers,

Dave.

[Brian]

If the arrow on the gen when looking at it from the drive end points in a clockwise direction then that gen does not come off a A10, but that doesnt matter as they can be used in either direction.

Hubie I am sure the problem here is all to do with the way it is hooked up.

Firstly use a texta to put a arrow on the body pointing in a anti-clockwise direction so you know where your at. Make sure it is wired the same as this picture. Then connect your battery to it with the positive on the body and the neg on the wire bridging D and F. If it motors in the correct (anti-clockwise) direction then test if for output, the pos of your voltmeter to the body and the neg to the wire bridging the D and F terminals. If it does not motor in the correct direction then swap the brush wires over and try it again. You have to get it to motor in the correct direction (anti-clockwise) with the pos being the earth. Once you get it to do this I am fairly sure it will work.

[trevinoz]

Dave,
             It MUST rotate in the driven direction or it will not generate!
If you swap your field wires it MUST reverse!
It does not matter what polarity you apply to test, it will always rotate in the direction it is connected for.
If your arrow shows clockwise, and it is at the drive end of the body, you have the wrong body, which doesn't matter.
What is the number stamped on the body? This identifies what the generator belongs to.
It sounds like all you have to do is reverse the field connections and all will be well as you have proved the generator will generate when you drive it in the wrong direction.
  Trev.

[trevinoz]

Gee Brian,
                   Great minds think alike. You beat me by four minutes!
     Trev.
             

[Brian]

Trev, this is one of those times I wish Hubie lived close by, I am sure his problem is just a matter of sorting out the wiring. I suggested he stick with the correct earth (positive) so the polarity is right when he puts it back on the bike.

[Hubie]

Hi guys,

The arrow is on the timing end of the dyno and points in the anti clockwise direction which is the direction of engine rotation from that side.  From the primary drive side, it rotates clockwise.  I will double check the wiring though to see how it is hooked up.

Okay the brush next to the D terminal looks right, the brush on the F terminal side goes to the body of the generator with another green wire that goes into the body under the brush plate.  There is also a green and yellow wire that is connected to the F terminal and goes back under the brush plate.  Is this right?

[Hubie]

Hi Trev,


The gen when power is put to it always rotates in the correct direction.  When it is driven in either direction it generates no appreciable output.

[Hubie]

when i mean the drive end of the dyno, I mean the end where the chain and sprocket goes onto.  the arrow here faces anti clockwise which is the same direction of rotation of the motor.  I quadruple checked it!

[Hubie]

Just a thought too.  If it has not been flashed, or if there is no residual magnetism left in the field coil, could it run as a motor but not generate any output when run off a drill or the bike?

[MG]

when i mean the drive end of the dyno, I mean the end where the chain and sprocket goes onto.  the arrow here faces anti clockwise which is the same direction of rotation of the motor.  I quadruple checked it!

When you are looking at the timing side of the engine, the crankshaft will rotate in clockwise direction, while the large dynamo sprocket will spin in the opposite direction (CCW), as it is attached to the idler pinion. So the dynamo will also spin CCW, driven by a chain from there. If your crank was spinning in the same direction, you would find yourself travelling backwards.  
However, if you are looking at it, standing in front of the timing side, and it motors CCW, then it is okay.

Just a thought too.  If it has not been flashed, or if there is no residual magnetism left in the field coil, could it run as a motor but not generate any output when run off a drill or the bike?

Having it motor requires having current through the field coil which will magnetize it, with the same result (residual magnetism) as per flashing it.


This is weird. Are you absolutely sure the bike is wired pos. earth? Sorry if this is too obvious, just to make sure.

Cheers, Markus

[Hubie]

I could not be more sure that it is positive earth and that it is spinning in the correct direction when motored.  Very confusing.

[MG]

Hmm, then the field coil connections must be the right way 'round. Very strange indeed.

There's only one more possible fault I could think of, which is a bad joint between the dynamo housing (painted maybe?) and earth (crankcases).
Where did you connect the earth lead of your multimeter (or the test bulb)? Directly to the dynamo body or somewhere else on the frame?

If we can exclude this, then I'm at the my wits' end (at the moment at least).