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Re: Dynamo giving trouble

Hi Mark

It is a good start when the dynamo motors on the bench, but sometimes it will motor but not put out a charge when fitted to the bike. Why, I haven't a clue.

"If" the dynamo has been reconditioned and has good brushes and the brushes and field coil leads have been connected correctly, I would clean the commutator with a plastic scouring pad and WD40, fit it back on the bike, disconnect it from the solid state regulator run the bike and test it with your Voltmeter (DC) (Google matchlessclueless, a guy there has written a very good step by step guide on flashing/polarising and testing a Lucas dynamo).

A good few revs above tickover, but not really caning it should give in excess of 12 - 13v. If the voltage is still very low, carefully take the end cap off the dynamo and whilst the bike and dynamo is still running, give the commutator a tiny spray of WD40. Sometimes, this will jump the dynamo into life (why, I haven't a clue, but works for me).

If that works, then I would suspect your new regulator isn't working. You can be lucky with Wassell type regulators, but I know quite a few people who can't seem to get them to work. The DVR2 I can thoroughly recommend.

With solid state regulators, they are polarity sensitive and they can get wrecked in miliseconds! So, be careful that you have flashed the dynamo to the polarity that you want, that the battery is earthed accordingly and most importantly that you have bought a regulator for that polarity and fitted it correctly.

Forgive me if you know all this and have tried this already.

Regards

Pat

ps Always fit a fuse on the non-earth side of the battery output lead. I use a 10 amp fuse.

email (option): sacombsashtrees@hotmail.com

Re: Dynamo giving trouble

Hi Pat & Noam,
Thank you both for your replies. I disconnected the 2 field wires from the end plate and re-tested the field resistance and got 3.4 Ohms. I noticed that the commutator was quite black so I gave it a clean with a plastic scouring pad and WD40. I re-tested the voltage output and but still only 0.5Dc volts.
I made the decision to remove the Dynamo from the bike again and dismantle it. On dismantling the dynamo I found oil that has come through the drive end bearing and has turned into what looks like a silver grease, (I think part of the cover might have been rubbing on the gear and the aluminium has mixed with the oil and this is why it looks like a silver grease). This was also covering a large part of the wires on the end of the armature. There was an oil film covering the rounded plate that holds the field winding to the case. Would this be causing the low voltage output? The field windings are all clean. My next plan is to give it a good clean, do I use an electrical contact cleaner? Is there any way of stopping the oils from entering the dynamo?

Cheers
Mark

email (option): skid1@live.com.au

Re: Dynamo giving trouble

The clutch in the end of the magdyno could be slipping as soon as you try to load the dynamo.

Re: Dynamo giving trouble

I had a problem with electrical contact cleaner. It seemed to react in some way with the carbon brushes and leave a black smear on the commutator. I found WD40 best.

Out of interest, when you got it to motor, was it spinning in the right direction?

email (option): sacombsashtrees@hotmail.com

Re: Dynamo giving trouble

Quote:

"I them removed the dynamo from the bike and connected it to the battery and it motored in the correct direction."

Noam.

Re: Dynamo giving trouble

Thank you all for your replies. I will be checking the clutch before it all goes back together. Is it common for oil to get into the dynamo. There was no seal on the drive end of the shaft, should there be a seal.
Cheers,
Mark

Re: Dynamo giving trouble

The seal is inside the timing cover, not in the mag-dyno unit.

Re: Dynamo giving trouble

You are correct Ian I forgot about that seal.
I have given the dynamo a good clean and reassembled it. I redid the Ohms test with the dynamo fully assembled and go a reading of 3.2 Ohms. All good he said to himself. I them tried to turn the fibre gear in case it was slipping buy using a large screw driver through the opening where the dynamo goes but it would not turn. I placed the dynamo back in the bike and fired it up checked the voltage at the dynamo and still only got 0.5 Volts.
I know there must be a problem with the oil seal in the timing case but, I am just trying to get the bike going for this weekend as it is the All British Rally at Newstead. Then after next weekend the whole bike will be dismantled and rebuild for the International Rally in November.

If I was to test the dynamo on the bench for voltage what RPM can I run it at.
Any suggestion on where I go from here would be appreciated.

Cheers,
Mark

email (option): skid1@live.com.au

Re: Dynamo giving trouble

If you get two wires joined at on end, put one end in the D socket and one in the F socket. hold on to the side of a 12 volt bulb the end of the bulb hold against an earth point on revving the engine it should light the bulb. If this doesn't work I think you are looking at another armature for the dynamo.

Re: Dynamo giving trouble

Hi Mark

A battery powered hand drill may rev sufficiently to get the dynamo to kick in. However, you may need it to revolve a little quicker. Don't rev the dynamo for too long though as you have no way of regulating the strength of the field coil.

Also, have a look at BSA Technical Sheets 808 and 808A (808 is negative earth and 808A is positive earth). I can't say that I have paid any attention to the brush location on these two wiring diagrams, but they do seem different (F still goes to F and D to D). I was going to ask someone like Noam why they would differ.

I have been trying to get my small mind round which wire goes where on my field coil for an E3L as I have no way of distinguishing which of the two wires go where (i.e. which one goes to F and which to earth). They are both cut short and both black!

Regards

Pat

email (option): sacombsashtrees@hotmail.com

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