Could a sh775 kill a stator?

[posplayr]

The only thing that is getting hot are those things that are carrying a lot of current. The only thing carrying primary current is either a diode or an SCR; in total that is items al lof which drop between 0.5-1.0 volts when forward biased/activated.

[Gorminrider]

Sorry for being cranky but you are grasping at straws and ignoring the obvious.
You can read the voltage across the R/R when shunted right from the plots in that link. It is less than 1 volt.

Since you mentioned a base, I assume you are referring to SCR's and not the MOSFET shunt R/R. The SCR does not have a mode where the transistor is operated in the unsaturated mode. It is either full on or full off.


http://www.allaboutcircuits.com/text...rectifier-scr/

OK! thanks. That is more useful than what I was reading... yes, I am referring to SCRS (as I thought was plain), seeing as the old R/Rs were SCRs . and my speculation does revolve around a concern that these do not have the cutoffs or breakdowns that are as sharp or "square" as I would have thought and acting with more heating being more resistant...I know for instance that zener diodes do not break down exactly"square" (if you get my meaning!) and ..equilibrium in a charging system is a constant change of up and down..example: The shunt is engaged, the system voltage drops, below the setpoint..... The shunt is therefore disengaged and voltage rises above the setpoint and the shunt is re-engaged...over and over, very quickly. If it is not the scrs, then some component is giving off the heat which I think is the fact of burned out oem R/Rs. ( aside: that usually keep conducting through their rectification stage which is a clue) The why seems important to me. But "replacement" is probably more useful!
It seems to me the same cycling and "hunting" for stability is going to be going on in the series type or the Mosfet shunt type but where the series type is opening and closing a coil rapidly the other ( the shunt) is not. If it is Granted that the shunt-type is allowing more current in those same coils the comparison does still not seem a "no-brainer" to me.

[posplayr]

Well, I fail. Old R/Rs burn out, old stators burn out. I'm not getting "why" in this course so I think I'll drop this course and The "Professor" is really cranky. But I'm happy enough with my speculation that the base is not being fully saturated and therefore it gets hot acting as though it has a higher resistance....combined with a semi-mystical grasp of hysterisis and other Mysteries, it'll probably tide me over until I can find a more satisfying answer.

Sorry for being cranky but you are grasping at straws and ignoring the obvious.
You can read the voltage across the R/R when shunted right from the plots in that link. It is less than 1 volt.

Since you mentioned a base, I assume you are referring to SCR's and not the MOSFET shunt R/R. The SCR does not have a mode where the transistor is operated in the unsaturated mode. It is either full on or full off.

http://www.allaboutcircuits.com/textbook/semiconductors/chpt-7/silicon-controlled-rectifier-scr/

[Gorminrider]

The proposition that there is 6 ohms of resistance in a shorted R/R demonstrates a lack of any real grasp of the basic operation of the circuit.

Well, I fail. Old R/Rs burn out, old stators burn out. I'm not getting "why" in this course so I think I'll drop this course and The "Professor" is really cranky. But I'm happy enough with my speculation that the base is not being fully saturated and therefore it gets hot acting as though it has a higher resistance....combined with a semi-mystical grasp of hysterisis and other Mysteries, it'll probably tide me over until I can find a more satisfying answer.

Not had an SH775 fail, but when I installed it two 1/2 years ago, I deliberately left in a slightly-cooked stator that wouldn't normally last the summer with a shunt RR.

good news,Grimly. You won't mind if I quote you as an illustration of a few of my puzzles? It's not about you and you needn't answer but I read similar all the time..... I'm not sure how you know it wouldn't last with a "shunt R/R"...but which shunt R/R is likely part of my question too. And the exact meaning of "cooked"? Is appearance is due to oil-vapour being burned onto the stator by the stator or if the oil vapour is merely discolouring the varnish....or if the varnish itself is Truly toasted and the varnish flakes off...pretty plain on a burned-out electric motor where the varnish flakes off leaving bare wire. Discolouration does not flake off.
I am not sure either how old your stator is or how many miles it has. Do stators have a lifetime expectancy? Are the stators made in 1980 failing just because their varnish is poor or aged out like tire rubber? questions questions.
The one thing I surmise from a lot of posts I have read: Replacing all the components is going to be a good thing and should give at least the mileage the old ones did.. even with the unpopular shunt R/R which, I surmise is an average 20 -30 thousand miles?( a very rough guess) and that might be enough that I don't have to deal with it again..

[OldVet66]

Not had an SH775 fail, but when I installed it two 1/2 years ago, I deliberately left in a slightly-cooked stator that wouldn't normally last the summer with a shunt RR.
Guess what? With the 775, it's still working fine - 14.5V peak, 14.1V at 3K, all the lights are better than ever and the bike's running smooth.
I expect it will fail sooner or later (the stator, not the RR) and I'm ready for it, as it will have proved something, to me at least.

I did the same with my Compu-Fire. The blackened stator lasted exactly one year before it gave up. Installed a new stator and it has been working fine for years. Nothing over-complicated about that except an over-opinionated mouth.

[Brendan W]

There was the Irishman with an inferiority complex - He thought he was only as good as everyone else

[mainiac]

Not had an SH775 fail, but when I installed it two 1/2 years ago, I deliberately left in a slightly-cooked stator that wouldn't normally last the summer with a shunt RR.
Guess what? With the 775, it's still working fine - 14.5V peak, 14.1V at 3K, all the lights are better than ever and the bike's running smooth.
I expect it will fail sooner or later (the stator, not the RR) and I'm ready for it, as it will have proved something, to me at least.

I was leery of my stator as well but it passed the test so I went with it. Not sure if it was the original. As I said no issues yet.

[Grimly]

So has any one here had a sh 775 fail? I replaced two regulators in three years and this spring installed a 775 with good results. Granted I only put on about 4500 miles this summer.

Not had an SH775 fail, but when I installed it two 1/2 years ago, I deliberately left in a slightly-cooked stator that wouldn't normally last the summer with a shunt RR.
Guess what? With the 775, it's still working fine - 14.5V peak, 14.1V at 3K, all the lights are better than ever and the bike's running smooth.
I expect it will fail sooner or later (the stator, not the RR) and I'm ready for it, as it will have proved something, to me at least.

[posplayr]

I don't know where to start...

Save your typing, this says it all.

http://www.thegsresources.com/_forum/showthread.php?243944-Series-R-R-installations-at-the-GSR

[Grimly]

More proof that you are overcomplicating and overthinking this extremely simple system. And maybe obsessed.

The sh 775 goes bad at least just as often as any other reg rec and the gs issue is the suzuki regrec.

Stators don't care how much power they put out. They either can or can't keep up and they couldn't care less either way. The bulk of the power distribution and management is handled by the reg/rec.

shunt regrecs have been working since the time of cave men. except suzuki shunt regrecs.

Bye now.

I don't know where to start...

[posplayr]

^ you have a serious inferiority complex

You don't even know what inferiority is.

^ you have a serious inferiority complex

[posplayr]

Just to put a bow on this for anybody reading the thread.

An SCR is a bipolar device and the relevant performance for the current analysis is its forward voltage drop when activated. I don't have any spec sheet in front of me but the number is going to be similar to a forward voltage drop of a diode which is about 0.5V for a high power device. The reality is there is a exponential Voltage to current profile, but the limiting voltage with ever increasing current (to the rated limit) is about 0.5V.

On the other hand a MOSFET is a Field effect Transistor that operates on a different principle. The relevant performance of this device is the equivalent resistance of the channel when fully activated. The higher the current rating the lower the resistance. It is also temperature dependent. A 25-50 amp part is going to be in the 0.01 to 0.050 ohm range. Again I'm not going to look up a specific part appropriate for this design but that is what they are. The SSPB for example is a 10 amp FET part in the 60-80 milli ohm range.

For simple circuit analysis , it is much easier to use the FET resistance number as it is a pure resistive parameter and can be compared to the stator resistance which is a couple of ohms. The SCR is not going to be quite as efficient and will use dissipate more power but is close enough for the purpose of the analysis.

In order to short teh terminals of a device that has 1-2 ohms of internal resistance, you have to apply a resistance across that device that is substantially lower resistance than the device itself(the stator). That means to short the stator the R/R equivalent resistance has to be measured in 10'S of milli-ohms and clearly not 6 OHMS!!!!

The proposition that there is 6 ohms of resistance in a shorted R/R demonstrates a lack of any real grasp of the basic operation of the circuit.

[Gorminrider]

no, I'm not saying mosfet and I have read general specs of SCRs but we don't communicate very well so yes, we might as well "end this here"

[posplayr]

.. I get that it can ideally be, but if not, it might be just something less than 6 ohms . Somewhere around full-conduction there are halfway stages that are making them hot. Why else invent a mosfet type? Your model of 0.05 ohms suggests that as your stator burns, a shunt type regulator is colder than the wires attaching it- not impossible; connections ARE often cited- (see 850combat's post?) but anecdotally, how many replace the stator while the R/R is perfectly fine? I think not many. They seem to fail as a pair, or the R/R fails first...
anyways, I've got to get back to the rocket I was building

You tell me the resistance of as power mosfet can't possibly be 0.05 ohms(have you ever even looked at a spec sheet for one?) but it can be 6 ohms????!??
Does 6 ohms across 3 ohms of stator sound much like a short?
Even the bike's electrical system is R=V/I=14/14= 1 ohm.

I'm trying to be nice; so I'll just end this here.