dynamo

[Brian]

Frankenstein, its not too difficult to rebuild a dynamo. If you have never done one or are not confident then maybe you know someone who could help, most older auto electricians will be well versed with generators. Alternatively the exchange unit may be the way to go.

Most manuals have a exploded view of a generator in them to show you where the parts all go. There are no tricky bits in them however, no shims or spring loaded bits etc. If you decide to do it yourself just take carefull note of how it comes apart. You must be very carefull not to damage the field winding or the armature but otherwise it straight forward.

[groily]

And if you were happy to take it apart and reassemble, you could get an exchange armature for a lot less than that if that's the problem. The only hard-ish thing is getting the field coil off and back as discussed already. Then there's the question of ensuring the little end plate on the drive end is well attached, with reasonable screw threads and screws (they do tend to be a bit tired often), plus being happy with the bearings and their housings. No slop. Otherwise it should be painless. And at least it's something that can be done in comfort on the kitchen or living room table!

[LJ.]

Yes do have a go! It's not too difficult and quite satisfying when you've done it. Lets hope its nothing like this... but still fixable!

Edit... Take care of that insulating board thingy it is rather fragile, mine is broken as you can see, there is only one screw holding it into place and can come loose.

[frankenstein]

hi...and thanks to all for your info..i am going to give it a go...i have rebuilt engines and such like in the past...so this should not be to complex....it was a real pain finding out that the cleaned dyno failed again so quick  as it took a bit agro to get the out timing cover to stop leaking oil...on the plus side my dvr2 solid state reg arrived today and looks very simple to fit...now to tell the wife i have to spend some more cash...mmmm..could be tricky !

[RichardL]

LJ,

I think your commutator might need a bit of service.

Richard

[LJ.]

Oh it was well and truely replaced with a new one Richard! But what a mess in there when I opened it up.

[RichardL]

I failed a couple of cheap gel batteries before following the regulator adjustment instructions in the Haynes manual and have not failed another since.

Well, I spoke too soon about not frying cheap batteries with my CVC regulator. It seems another (thr third) has gone. I am not even bothering with trying to adjust the CVC again. Rather, I am going right for the DVR2. I will let you know how that turns out, but I have high hopes considering all good things reported herein.

Richard

[groily]

Think you'll be happy Richard. Fingers crossed anyway. I just bought my third dvr as I gradually replace all other regulators on dynamo bikes. Can't remember if you're running 6 or 12 volt, but shouldn't make any odds apart from how you wire it in- they seem to just work. And the instructions are crystal clear. So far, I have found that topping up batteries regularly is a thing of the past with them - which indicates that they do regulate well in all normal conditions. I have standard reasonable quality (Yuasa)  lead-acid batteries in my bikes, be they 6 or 12 volt. Have never tried gel, yet.
I've been told that for anyone who uses the excellent Cyclon 2 volt cells linked up as required, the charge rate can appear a tad high when the Cyclons are part-discharged, owing to the low internal resistance in or between the cells. This manifests itself,  not surprisingly, in a high current being generated by the dynamo until the cells are up to full charge. Perhaps current regulation will be the next step in the Fight for Light and Battery Life, though I have no real understanding of how difficult that is to manage. However, CVC boxes in many old pre-alternator cars had a third stack/coil to do just that. 

[Dynamo Regulators Mike]

Hoping you are all happy with the DVR2's.

Interesting that you bring up the subject of current limiting, Bill. It is true that many old car regulator units included current adjustment on the third bobbin, but the more compact Lucas bike type also includes a non adjustable current limit, to prevent excess battery charge. At the same time the dynamo armature is protected from excessive current for too long.

It is actually quite a challenge to incorporate current limiting in the electronic regulator. What value of maximum current is acceptable? This should reasonably depend upon the dynamo type, as well as perhaps the battery type for full protection. From the electronics point of view limiting the current is simple enough in concept, tricky in practice. The simple one transistor turned on by drop across a series resistor really dissipates too much heat. Something more complicated is indicated, if going to an integrated circuit solution it is impossible to maintain a complementary circuit for + & - earth. More development expense and two circuit boards are one result. It becomes tricky to manage all the possible variants in production. And the extra cost of components will help to price the resulting products out of the market, especially to less discriminating purchasers than typically found on this forum.

It could well be argued that as long as not too large (nor too low internal resistance) a battery is fitted then the high initial charging current when discharged, will be of small enough level and short enough duration to avoid damage to battery or dynamo. A suitable fuse serves as a traditional protection mechanism as well. As a final resort keeping revs and thus the charging current down a bit to prevent nuisance blowing with a low battery (electromechanical sympathy perhaps). In reality this should be a rare scenario, and the better life anticipated from precise voltage charging offsets this potential limitation when using (most ????) present electronic offerings.

Back to work I guess.
Mike

[trevinoz]

I find it hard to believe that some of you are having so much trouble with the electro - mechanical cvc units.
I strip them and clean all contacts, ensure the resistor has not gone open circuit or high [usually caused by rust], reassemble and set all the clearances as per the book.
I adjust electrically on the bench with a generator. I was using a variable rectified supply but found that the settings varied when connected to the generator on the bike.
So far I and many of my associates have had years of trouble free riding.
The only problem I have encountered is the bloke who " wanted a bit more out of it" and altered the settings and immediately started using battery water. Lucky he didn't burn out his generator!
                           Trev.

[RichardL]

Trev,

I hope the "hard to believe" part of your message is tongue-in-cheek. After all, you are saying you have a generator on the bench to test with, which, I presume, means that you also have a motor of some sort that can turn the generator at enough RPM to perform the test. Further, originally, you had a variable rectified supply. As for myself, I wouldn't mind trying to get the CVC running again, but I have already blown my way through about $100  in batteries and would prefer to avoid flushing more money away on them. Additionally, the mounting bolts are broken from my CVC, so its replacement seemed inevitable anyway. The $95 (including shipping from the UK to the USA) for the DVR2 seemed a reasonable investment, to avoid more fried batteries, in case I was not as successful as you in tuning the CVC.

Richard

[trevinoz]

Richard, I assure you I was not "tongue in cheek" with my comments about the cvc regulator as I have resurrected many of them and they are all working well. My only failure to date was an Indian made pattern type and it would not stay in adjustment. I have found the pattern regulators are not as well made as the Lucas originals but if they are adjusted correctly they work OK.
The DVR2 is a very good regulator. I recently converted a CAV generator from a 1921 Vauxhall to a regulated output in lieu of the primitive system from that era. I used the DVR2 in the original relay box and the owner is very happy. Hopefully no more burnt out field coils.
                                     Trev.

[RichardL]

Trev,

Sorry. I had a suspicion I might be misunderstood. What I meant was that It would be less trouble for you than, for example, me, because you have the bench-testing gear. I was not doubting, at all, your success with the CVCs. I was, however, doubting my own chance at success absent the bench gear.

I hope this explanation keeps us on the square.

Richard

[groily]

Thanks (manor)Mike for wise words re current management. Just had a chance to read them after being away on holiday for a couple of weeks. Reckon you're right about the sympathy thing, and just about understand what you said about 'how' and 'how many amps'! Pleased to say that all my various electrical bits and pieces seem to be working well, and given reasonable quality, reasonable size, reasonably well-charged batteries - no problems at all. The Cyclon point arose from seeing the level of charge being delivered, even with lights on, on another bike thus fitted - which was towards the  dynamo's upper limit until the cells were up to speed. Hence the current management thought. I guess the moral is - keep the battery charged up, whatever type it be, if you don't use the bike a lot. Which won't affect me I hope.