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1949 ES2 dynamo?

Submitted by simon_amos on Mon, 06/05/2013
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Can I pick someone's brain regarding dynamos?

I not convinced mine is charging properly so; I've bridged terminals F & D and passed the output to Earth via a bulb, blipped the throttle and the bulb goes DIM rather than brighter/popping as expected ... any ideas before I start looking at the commutator and brushes?

TIA

Ian

Submitted by ian_richtsteig on Tue, 07/05/2013

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Previously ian_richards wrote:

Can I pick someone's brain regarding dynamos?

I not convinced mine is charging properly so; I've bridged terminals F & D and passed the output to Earth via a bulb, blipped the throttle and the bulb goes DIM rather than brighter/popping as expected ... any ideas before I start looking at the commutator and brushes?

TIA

Ian

While you have the F & D bridged, connect a mulitmeter, set on volts, between the bridged wire and earth and check voltage. Volts should rise with revs.

Submitted by simon_amos on Tue, 07/05/2013

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I have tested with an analogue multimeter and the readings rose with revs to about 6 volts and then start to drop as the revs increase.Mmmmm?????Previously ian_richtsteig wrote:
Previously ian_richards wrote:

Can I pick someone's brain regarding dynamos?

I not convinced mine is charging properly so; I've bridged terminals F & D and passed the output to Earth via a bulb, blipped the throttle and the bulb goes DIM rather than brighter/popping as expected ... any ideas before I start looking at the commutator and brushes?

TIA

Ian

While you have the F & D bridged, connect a mulitmeter, set on volts, between the bridged wire and earth and check voltage. Volts should rise with revs.

Submitted by michael_sullivan on Tue, 07/05/2013

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Sounds to me as if the brushes are bouncing on the commutator as the revs rise.

Have you checked the condition of the brushes and/or the springs?

Submitted by simon_amos on Tue, 07/05/2013

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Yep, done that today and they look fine.I cleaned the brushes and the commutator to no avail.The springs looked fine as well.Mmmmm?Previously michael_sullivan wrote:

Sounds to me as if the brushes are bouncing on the commutator as the revs rise.

Have you checked the condition of the brushes and/or the springs?

Submitted by gordon_johnston on Tue, 07/05/2013

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Without getting out my books, I think that this might imply a duff field coil. Fairly easily checked if you measure the resistance. But I would need to go delving to confirm this.

Submitted by simon_amos on Wed, 08/05/2013

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Previously gordon_johnston wrote:

Without getting out my books, I think that this might imply a duff field coil. Fairly easily checked if you measure the resistance. But I would need to go delving to confirm this.

I have just checked the field coils using my multimeter.the minimum scale of which is 2000 ohms.This shows an resistance of 1 ohms in the wires.The reading between the F terminal and the dynamo casing reads 4 ohms, therefore showing a resistance reading of 3 ohms.This of course would be more accurate if my multimeter had a lower ohms scale.The dynamo in question is a E3LM -L-0 which had previously been rewound to produce 12 volts

Submitted by paul_wolf on Wed, 08/05/2013

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Previously ian_richards wrote:
Previously gordon_johnston wrote:

Without getting out my books, I think that this might imply a duff field coil. Fairly easily checked if you measure the resistance. But I would need to go delving to confirm this.

I have just checked the field coils using my multimeter.the minimum scale of which is 2000 ohms.This shows an resistance of 1 ohms in the wires.The reading between the F terminal and the dynamo casing reads 4 ohms, therefore showing a resistance reading of 3 ohms.This of course would be more accurate if my multimeter had a lower ohms scale.The dynamo in question is a E3LM -L-0 which had previously been rewound to produce 12 voltsThe resistance of a 12V field coil should be about 5.6 ohms,you will find that the resistance of new field coils (6 & 12 v)that are now avalible is different then the Lucas originals,that is way i rewind my own.You could have a fault on the armature and you will need a growler to check it.If you want me to check your armature i will free of charge you just need to pay for the postage.Paul Wolf Magneto & Dynamo Repairs.Tel:0117 9836702

 


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