175 electrical questions

[DewCatTea-Bob]

____ I had found that page-2 of this thread had become jacked*, so I had allowed it's original-topic to fall-off from my-own interest in further participation.
But now that it seems to have been put back on track (thanks to 'duck749' & 'ducwiz'), I now find a slough of stuff to respond to !
(* Not really meaning 'hijacked' of-course, but rather kind-of kinked-off, as the established flow had become interrupted & diverted,, that's merely-all I had meant by "jacked".)

hi ducwiz, yes i think the consensus is that its probably a 160 monza

____ It seems that Hans has forgotten what he should've learned before about the differences between the '40-watt' & '28-watt' stator-models, as the stator-version which you have is clearly-not the std.40w version !
I only held-off DECLARING it as an absolute 28w.model, in expectation of learning the resistance-levels of it's various power-coil windings. _ However even without such confirmation, the possibility of it being some-other stator-model is extremely remote !

heres a rough drawing of what i assume mine is doing.

____ That was a nice endeavor to have bothered to make a hand-drawing of. _ However while your yellow-coil/circuit is a fairly-good representation,, your red-one is not quite correct, and of-course your white-one couldn't be more wrong (sorry to say !) !
It's quite apparent that you (as well as ducwiz) have failed to take close note of the info presented within the (old/Oct.2014) thread that I've already provided a link to -(as obviously found in my first-post on page-1) ! _ So I now feel the need to include a copy of the related drawing posted over-there, within this-post as-well.

ive ordered a rectifier that dew cat tea bob pointed me towards

____ Actually I hadn't yet outrightly recommended anything in particular for your as-yet to-be determined system-project,, although you're pretty-likely to find a use for at-least one such power-diode unit, (and the-price I had found for such, certainly couldn't be beat !).

its looking increasingly like the stator is no good.

____ I don't yet see how you can already head towards such conclusion before you've actually determined whether the resistance-levels of it's coil-circuits are bad or not.
What has since lead you to suspect that your stator may-not still be good, after you've already logically determined that the engine must've been run with that stator as it was once installed ?


Hopeful-Cheers,
D.Bob

[DewCatTea-Bob]

[quote= Rick ...
" I've never unwound this style of stator coil,
this is how I think the lower coil is wound- like a center tapped transformer. "

____ A very visually-appealing drawing you've presented for us Rick !
The only likely somewhat misleading aspect about it, is that your indicated 7:9-ratio of white to red coil-loops ought rather be more like a 1:4-raito (or near-about 4 white-loops to 12 red-loops).
I've included a slightly altered version of your previously-posted drawing, (but I didn't also attempt to correct it's indicated turns-ratio).

[bodge]

hi bob,
i thought the 160 was the 28 watt,my mistake.i had (mis?)understood the fact that all my wires were grounded meant if it was a 28 watt it was faulty ? im probably just being thick but i cant see how any of the schematics posted could relate to my stator apart from the one from rick. ive read the thread you linked to a couple of times now and although its no doubt an interesting read to an electrical genius its beyond me,i was hoping for more of a plug this into that and bobs your uncle type of guide i realise now without being able to supply accurate resistance readings thats not possible.

[Rick]

Bob-
'visually appealing' isn't worth much if you think I have it wrong. I'm not sure I can reconcile the drawing you posted with what I see in the alternator, but I don't want to have an incorrect drawing floating around the internet.
The resistance measurements in your drawing match what I'd expect from my drawing, 84mΩ from white to ground, 159mΩ from white to red, sum up to 242mΩ, and your measurement was 243mΩ- maybe 'center tapped' was the wrong description, but the resistance of the red coil and the white coil sum up to the series resistance of both coils.
I'll attach a couple of pictures of the alternator I was referring to- there are 2 wires from the coil bobbin soldered to the white output wire at the center terminal on the output board, the red wire, and a wire soldered to the core at the other end of the coil.

28watt 0.jpg

28 watt 1.jpg

Point out what you think I got wrong- the drawing is meant to show the electrical layout, not physical- the windings are probably wound on top of each other and not separated like the drawing implies.

Bodge-

You're not 'thick', I think most people struggle with the Ducati schematics. Ducati built electrical/electronic devices before they built motorcycles, and I'm sure they had good engineers- just a little hard to understand what's going on.

Rick

[DewCatTea-Bob]

____ Just as I was next about to get-around to posting a response to the latest bodge-post, Rick has rather next submitted a post that more-so needs to be addressed firstly instead ! ...


[quote= Rick ...
" 'visually appealing' isn't worth much if you think I have it wrong. "
____ Well certainly-not "wrong", Rick,, rather merely-just questionable in regards to technical-accuracy. _ As it's still unknown as to what the exact actual turns-ratio is (in relation to white-circuit loop-turns to red-circuit loop-turns).
So your proposed depiction is nearly as good as any other (at-least for the present).



" I'm not sure I can reconcile the drawing you posted with what I see in the alternator, "

____ Seems things are flying-by before it's clearly established that whichever "drawing" has been properly matched to whatever "alternator" unit.



" I don't want to have an incorrect drawing floating around the internet. "

____ That's certainly quite admirable of you, (and it sure would be a more perfect world if most-everyone cared so well about their contributions) !



" The resistance measurements in your drawing match what I'd expect from my drawing, 84mΩ from white to ground, 159mΩ from white to red, sum up to 242mΩ, and your measurement was 243mΩ- "

____ First-off, that drawing you're referring-to is-not my-own !
Anyone who has followed the threads that cover the 4-pole alt.stators, ought realize that that-drawing was originally done my another member who had a rather QUESTIONABLE stator-coil, and he's rather the one who had come-up with those-figures (which were about half of what ought-to be found). _ So I've never measured .243-ohms between the red-wire & ground !
Rather, as I recall,, the commonly expected readings ought-to be nearer to
.15-ohm for white to ground;
.45-ohm for white to red;
and .6-ohm from red to ground,
(or similar figures there-about).
__ So if your drawing was based-upon those figures that you apparently had ASSUMED were expected as GOOD-figures for the unique-28w.coil, then that may explain why our respective expectations for the turns-ratio don't well correlate.



" maybe 'center tapped' was the wrong description, "

____ The term 'center-tap' is actually applicable, even-though the tapped-point (where the white-circuit cuts-in at) is actually a good-bit off-center !



" but the resistance of the red coil and the white coil sum up to the series resistance of both coils. "

____ Right, just as indeed they should !



" I'll attach a couple of pictures of the alternator I was referring to- "

____ I couldn't see them very well at-all, so I've tried to improve them and have posted the combo.pic result below.



" there are 2 wires from the coil bobbin soldered to the white output wire at the center terminal on the output board, the red wire, and a wire soldered to the core at the other end of the coil. "

____ Right, just as your artful drawing well depicts !



" Point out what you think I got wrong- "

____ What ever led you to suspect that I might think your drawing is "wrong" in any really-noteworthy way ?
I only ever mentioned that the indicated-number of white-circuit loop-turns are too-great in comparison to the respective-number of red-circuit loop-turns,, and that particular relationship hasn't ever yet been established (as written-in-stone).
So-thus I really have nothing to point-out.
__ Thanks for your helpful contributions Rick !


Dukaddy-DUKEs,
-Bob

[DewCatTea-Bob]

____ Now finally back-to the last bodge-post...


[quote= bodge ...
" i thought the 160 was the 28 watt,my mistake."

____ Well actually that's no "mistake" really, as the 28w.stator-model really is indeed that of the 160-Duke !
I've no idea what has caused you to ping-pong on this notion.



" i had (mis?)understood the fact that all my wires were grounded meant if it was a 28 watt it was faulty ? "

____ I'm at a loss to properly comprehend exactly what your sentence is actually supposed to be saying.
__ Perhaps you've become confused because of some related-stuff that ducwiz has posted. (?)
If so, then please try to keep info which I've posted, separated in your mind from that which you've read elsewhere. _ As my postings alone should-not lead to any such confusion.
__ Perhaps confusion has arisen having to do with the fact that the 28w.model's identity can be discerned from the 40w.version due-to the fact that only the 28w.version is supposed to have NEAR zer0-ohms between any & all of it's connection-leads and-also ground,, and yet, any coil-circuit that measures ABSOLUTELY zer0-ohms -(0.00) must be "faulty", also as-well.
So please don't confuse mere 'continuity' with the likes of 'short-circuiting',, as the coil-windings are OBVIOUSLY grounded to the stator-plate and-thus are supposed to test-out with continuity to ground, (unlike the 40w.model's coil that ducwiz's speculation was in reference to).



" i cant see how any of the schematics posted could relate to my stator apart from the one from rick. "

____ Of-course Rick's fine piece of work is as you rightfully conclude,, but by the time you've gotten a firm grasp of what's exactly what, you ought then well realize whether everything presented is or isn't meant-to relate to what you've got.



" i realise now without being able to supply accurate resistance readings thats not possible. "

____ Well if your stator was rather found to be in like-new condition, then you'd be good-to-go having already used your ohm-meter as a simple continuity-tester to've properly identified your stator's model-type. _ But considering it's apparent half-burnt actual-condition, it certainly wouldn't be prudent to go-ahead & trust it's functional-operation without being sure whether it's still up-to normal-specs !
__ I've included a closer view of your stator-coil in question, but it's still not definitely clear that it's burnt bad enough to be reduced to junk-status.
Perhaps you can provide a better lite & closer view of the coil in question.


Hopeful-Cheers,
-Bob

[bodge]

thanks for clearing that up for me bob,i think my low quality photos probably make my "burnt" coils look worse than they are, in the flesh ide probably describe them more as lightly saute'ed.
for now ill risk it for a biscuit and continue with the stripdown of the engine and cross that proverbial when i come to it on reassembly.
now i know ive got the 28 watt im a step further forward so again thanks to all for your help and advice.

[ducwiz]

bodge,

although mine differs from the schematic in that both coils are grounded and also mounted to the backplate in reverse order

Sorry, I overlooked the soldered end of the second coil, was misled by the schematics in the manuals. As a result of Bob's efforts to enhance the fotos, I realized my mistake.
I never came across such a stator plate here in Germany, but have to confess, that I did not examine a lot of n/c alternators.
For me, your electrical system seems to be depicted and described in a booklet from DUCATI, called "magneto booklet" for tthe US market, offered for download here: http://www.motoscrubs.com/Ducati_Electrics/Duc_Magneto.htm. Unfortunately, it does not show the inner circuit of the stator, and does not mention the output power. Anyway, it clearly shows a battery powered ignition, thus it's name was wrongly chosen.
I totally agree with Bob about resistance measurements. One needs a special (always not cheap) ohm-meter to determine the very low resistances of the coils, and to disriminate them from short circuits (to ground). In an earlier thread http://www.motoscrubs.com/forum/viewtopic.php?f=3&t=1775&hilit=+resistance#p13025 I described a method how to make accessory device, enabling common cheap multimeters to measure sub-ohm resistances.

In the UK, you may purchase a suitable bridge rectifier from Maplin http://www.maplin.co.uk/p/kbpc2501-25a-bridge-rectifier-ar84f

cheers Hans

[bodge]

thats great, thanks hans

[ducwiz]

I just uploaded the 160's circuit schematics for comparison. It differs from that shown in the magneto booklet - there is only a single rectifier diode, but no bridge rectifier. And - the 160 has a magneto ignition, as the ignition cut-out contacts (short-circuit kill switch) and the AC feed for the ignition coil (yellow wire) clearly indicate.



The 6V/28W alternator is mentioned, it has the same wire colours as yours.
Now, how to find out if your stator is a genuine 175 for battery ignition system, or a 160 type? Bob, any info, suggestions or ideas at hand?

Hans