Another Dynamo with no output

[Slippery Sam]

Hi, just been reading a bunch of threads and articles on charging and still no charge.
A10, E3L, 6v positive earth, solid state reg.
After a bit of research I did a few tests.
F terminal field connection to earth 2.9 ohms
D terminal to earth .9 ohms
Dynamo earth to frame 0 ohms
Tried flashing - didn't get much of a spark (it did spark but only a little)
Tried both methods I found - flashed F terminal only (+6v to frame, negative to F) and joining F and D together and flashing.
Dynamo is an original Lucas re-manufactured unit fresh out of a Lucas box - like brand new.
Has new brushes, wires are good and checked.
I get 0.01v from F&D together at tick over and about the same (not much fluctuation) when revved.
I have an SRM belt drive.
Removed brushes and the only thing I can think is the copper rotor (commutator?) looked a little black - I took it that would be from the brushes but I have just read about cleaning the commutator with meths?  I assume this means the entire surface that the brushes run on?

Any other ideas? Things to check/test.
I'm. Reluctant to assume the Dynamo needs a rebuild as its done nothing for 20 years (why I flashed it) - will attend to any cleaning etc needed though if time/oxidisation or whatever have affected the unit.

Apologies if this appears to be the same old war cry - I know it sounds like a great number of the threads I've read - however mine has no happy ending yet.  Its frustrating me a bit now because the build is otherwise complete and everything else seems to be in order (although clearly I still have the actually regulated charging to check but can't do that till I get something out of the Dynamo).

Any tips pointers or banter appreciated.
Raymond

[Slippery Sam]

Hang on a minute!
What direction should the rotation be for an A10?
My rotation arrow is pointing anti-clockwise when viewed from timing side!
Is that right?
If not it might mean some fiddly re-wiring?
I'll go hunting now but if counter clock is wrong - shout out and I'll attend to it right away and report back.
Raymond

[Bsareg]

Think it should be anti clock from timing side as runs off the idler gear. Join f & d terminals together, with belt or chain off , connect terminals to negative of battery ( if pos earth ) or visa versa. Dynamo should rotate anti clock, if not, swop over  field wires to correct. If it doesn't motor or motors erratically or very fast you will need tech help

[KiwiGF]

Hi, I had a similar experience......an additional check is to put some current directly through the field then spin the Dynamo with a drill and see if the armature can power (say) a headlight bulb.

The thing about the f and d check is that it relies on the residual magnetism to get the armature to put some "starting" current through the field to get things going. If your brushes have too high a resistance then sufficient starting current does not happen, putting some power directly through the field is a better test of the 2 coils.

It's ok to put a 6v battery straight across the field, for short periods at least, with a resistance of a 2.9 ohms only about 2 amps will go through the field.

If you can get a bulb lighting up then you can look at the brushes and reg side of things....

Edit: my Dynamo had not run for over 30 years, when I eventually got it going it would run for a couple of hundred miles then stop charging  , cleaning the brushes (which were not THT dirty) got it going again but only for another couple of hundred miles , replacing the brushes with new ones sorted it permanently, maybe the brushes degrade over time

[Slippery Sam]

Thanks guys,
So looks like it's the right rotation / direction
I'll do the suggested extra test first chance I get.
It's always a pity to have just literally finished buttoning everything up, new gaskets, nicely sealed and oil tight, all the fittings and everything in place - then have to pull everything - so be it.  Let's get it finally sorted.

cheers.

[Bsareg]

Before stripping timing side you could try a temporary wire from field direct to live of battery and start engine. If all is well you should get a charge with lights on. Don't rev too high or you will blow bulbs. If this works, your trouble is elsewhere,  cutout usually.

[BSA_54A10]

When I leave most of my bikes a long while between rides they sometimes fail to charge.
The cure is to give the contacts a quick  squirt of contact cleaner then occasionaly holding down the contacts by passing the cut out.
Only takes a few seconds, keep the headlamp turned on and when it lights up let go.
Also remember that it is regulated so if the battery is fully charged you get no output from the generator

[Slippery Sam]

Okay - we're half way there now - whoop whoop.😀😀😀
I used Trevor's method and powered up the field and used a bulb to check the output.
so after cleaning up the commutator - I fired her up and instantly got a glowing bulb, little rev and the bulb got brighter - so far so good.
This was all done directly on the Dynamo wiring disconnected from the loom.
So all back together and fired up again. No charge on the ammeter (with lights and all on).  So next is off with the seat and a fiddle about with the regulator wiring to see what's what there.  I have a charging cable fitted to the battery so easy to check battery voltage.  I guess I need to see the Dynamo output voltage (7+V) going in to the reg and try to see where it's going or not.
Will update once I get that far - just had my new Sky Q box fitted so going to play with that for a bit😀
Raymond

[orabanda]

Hey Raymond,
Have you tried another battery?

[Slippery Sam]

Got it - charging like a power station now 👍👍👍
Thanks orabanda - battery is a brand new gel full size and sitting at 6.45V
I have to spill the beans now in the name of maybe helping others😬
After cleaning the commutator and getting a really good output i moved on to the reg end.
Nothing nada
So did the same test as before (6v on the field and a bulb on the yellow) - nothing
Fiddled about checked resistance on the full length of wiring, all connected and no shorts.
So from no output to start with all I'd really done was
Polarised - no output
Cleaned commutator powered up field - got output
Buttoned everything up - no output.

Is anybody screaming - DYNAMO END COVER yet?

Off with the cover - one of the brush wires looked a little trapped!
Tried it with the cover off and hey presto - full proper charging - get in.
Re-routed the brush wire and carefully reassembled - boom full charging.

Now all back together and working like a dream.

Only negative was it was a little chilly in the workshop tonight so wore my Berghaus micro puffa and burned the sleeve a beauty on the hot header pipe.  Took me ages to scrape it off with a plastic ruler and polish back to mint.

Thanks for all the pointers, tips and tests - we got there in the end - albeit - it was just the cover trapping a wire.

I guess the commutator did need cleaned and the field polarised so no foul doing everything from first principles - and of course I know how to do it properly now 😀

Thanks raymond

[KiwiGF]

Thanks for letting us know, I guess you probably had the cover off when measuring the coil resistance otherwise the short would "probably" have shown up....well done for perserving !

I'd forgotten the internal short to earth problem, on mine I had some sort of plastic springy coil twisted around the wires attached to the brushes, and free to slide up and down a bit, which did not inspire confidence, and it also needed careful routing to limit the possibility of shorts, the non OEM replacement brushes had a better type of tubular insulation.

[duTch]

 I killed at least two batteries with much the same issue a couple of years ago, outlined in a hijacked thread (page two) ;
 
 http://www.a7a10.net/forum/index.php?topic=7959.msg66201#msg66201 

[BrianS]

Warning - thread hijack - but I did a search on dynamo rotation and this was the most recent thread on the results!

I am not sure if the dynamo on my A10 is the original. I want to send it off to have it refurbished and upgraded to 12v. I need to tell the firm doing the upgrade the direction of rotation. The arrow stamped on the dynamo body (see photo) indicates it rotates anti-clockwise. Is this correct for the A10 please?

Also, does the "8     62"   indicate it was made in August 1962? My A10 is a 1955.

Brian

[beezermacc]

Anti clockwise is correct, also 8-62 indicates manufactured August '62. The original dynamo on your bike would have had a Bakelite cover, not the one-piece which yours has, presumably. If you need any help with electrical stuff give me a ring during normal office hours. Priory Magnetos (and dynamos!) Ltd. Andrew

[BrianS]

Anti clockwise is correct, also 8-62 indicates manufactured August '62. The original dynamo on your bike would have had a Bakelite cover, not the one-piece which yours has, presumably. If you need any help with electrical stuff give me a ring during normal office hours. Priory Magnetos (and dynamos!) Ltd. Andrew

LOL - I was getting the info to send to you with the dynamo Andrew 

I will be ringing up on Monday and hope you can take on my mag/ATD rebuild and dynamo 12v upgrade!

Brian