I've actually seen guys on older 70s Hondas unbolt the regulator, or rectifier, whichever it is, and hang it outside the side cover so it would get more air. They claimed this was the only way to keep it running.
-Kyle On Wed, May 19, 2010 at 5:11 AM, <[email protected]> wrote: > Hi > > The original SHINDENGEN regulator of the 650 is a primitive model. It > contains two functions : > > 1 - A three phased rectifier bridge, which converts the 3ph AC voltage from > the stator windings (yellow wires) to a near DC voltage. > 2 - A regulator, sensing the (1) DC voltage and producing a variable > current fed to the excitation winding located in the center of the stator > (white and black wires) > > The (1) function is basic, rugged and should never fail. > The (2) function, on this model, is a simple power transistor creating the > equivalent of a variable resistance beetween the +12V potential and the > excitator winding in order to regulate the excitation current. > > This regulating scheme has a bad energetic efficienty, which makes the > regulator dissipate much heat, especially when the engine is in high revs : > voltage produced by an alternator increases lineraly with rotation rate and > to regulate to ~13V the output DC voltage one must lower the current in the > excitation winding. Running the bike too long at high revs (for example > riding uphill for dozens of miles over 5000 rmp) can heat the regulator in > such a way that it's temperature overpasses the limit and the internal > electronic components are destroyed. But in that case, with an air cooled > engine, some damage can happen also to the engine... > > There is another common cause of failing on a lot of bikes. The voltage > produced by the alternator at high revs can go over 150 V if not regulated. > Of course the regulator should limit it, but in the regulation loop, there > is a damping, to ensure stability. It means that on short period of times, > you can get, say, 50 V during milliseconds at the ouput of the stator. > Worse, you get a negative 50 V voltage one AC half cycle out of two. > Problems arise when the weather is wet, because the yellow wires from the > stator are in the same connector as the black and white wires. Through some > humidity bridge in the connector, you can have a return of -30V to the > output transistor of the regulator, which usually fries it. > > Up to this, I just describe problems common to any bike. I have bike > (Yamaha) where the previous owner, tired to change the regulator, replaced > this connector by soldedrings and an insulation paste ! > > Now, third problem specific to the NH. The alternator design is flawed : in > my opinion it's probably the main reason which pushed Honda to stop abruptly > the production of this bike which was a good success on the market. The > alternator being poorly engineered (thanks Hitachi), they were obliged to > push at the limit the value of the current in the excitation winding, in > order to get an acceptable value of the useful magnetic flux beetween the > rotor and the stator. And so, this winding is very near of it's thermal > limit. And this is especially the case when people ride their bike "like a > Harley", i.e. in low revs ! Yes, because in low revs, in order to get a 13V > DC voltage out of the regulator, you must increase the current in the > excitation ! In that case, the output transistor in the regulator dissipates > few energy, but the excitation winding dissipates a lot of thermal energy > (proportionnal to the square of the current), gets hot, and if the internal > temperature reaches the threshold of destruction of the insulation of the > wires, you get local fusions and short circuits in the winding. In many > cases, this happens in the heart of the winding and creates short circuits > beetween neighour wires, decreasing the resistance, the magnetic efficiency, > needing the regulator to increase the current, and so on until death. The > user sees the charging performances decrease gradually and, one day or the > other, he comes to this list asking "must I change the battery" ? Check the > history of the messages on the list. > > There is worse ! In the previous case, as the central winding looses it's > performance, the regulator must create higher and higher currents, because > it's internal regulation loop doesn't know that the winding is under > failure. So it comes in the heating state, that I described first for too > high revs, and this for normal revs. And it fries because too hot. > > Now, the cherry on the pie, when this regulator fries because it's too hot, > usually it does it putting in short circuit the output transistor (there is > a meltdown in the silicon). What happens then is that you have no longer any > regulation : like if the central excitation winding of the alternator is > permanently connected to 12V. This will of course, even if the central > winding was not so damaged, fuse it completely, which by itself is the fatal > and normal issue, but by the way, can create for some time too high DC > voltage on the battery which will make the electrolyt boil and fry the > battery. > > And better again than the cherry on the pie... call it the big Sh... in the > boots. In case of too high voltage on the battery, you can also get an > overvoltage on the general +12V line, which damages some sensible devices > like the ignition system or other eletronic device on the bike. > > No need to explain you how much it can cost to repair all that ! In some > cases, it could be better to sell the bikes for spares. > > So, my recommandations are, in case of problem or even for preventive > maintenance : > > - Measure the resistance of the central winding of the stator. Under > nominal value (5 ohms), is probably damaged. > - Change the regulator for a modern one. Buy it at Electrex (UK) or > Electrosport (US). The output stage is FET driven, with a protection loop > preventing over current and overheating of the regulator. It will cost less > than buying the f... Shindengen original model at Honda. > - Take your stator to repair. Say to the professionnal to rewire only the > central winding, if the 3ph windings are ok (usual case). Ask him to take > professionnal grade wires, with the highest possible temperature class. You > can ask him to go ONE point of gauge higher for the wire, which means take a > thinner wire, and to increase the number of turns of the winding in order to > occupy all the available space in the coil. This will decrease the amount of > heat dissipated in the coil, for just a little lower magnetic flux beetween > rotor and stator : you will begin charging at 1500 RPM instead of 1200. If > you don't drive for hundred miles at 1200 rpm on highways, you will never > notice any charging problem. And if you like to make home work, do it > yourself... > - Take the black and white wires out of the 5 points connector on the > stator harness, and install a separate connector for them, leaving the three > yellow wires alone on the connector. This especially if you have to drive by > wet weather. > - If the battery is damaged, buy one wherever you want (Honda dealer, Wall > Mart...). > - As I already wrote it on the list, if you don't drive at night, put a LED > H4 compatible headlamp, and also LED rear lamps and turning signals lamps. > Of course, don't add any additional electric equipment on the bike. > > And enjoy your nice beloved bike ;) > > Jean-Pierre > BTW electrical engineer, now professor in electrical engineering, in the > future professionnal advisor for NH owners ;) > > > > At 18:58 18/05/2010 -0700, MN blue wrote: > > Hello all, >> >> I have been chasing electrical problems on my 83 650 since I got it. >> I think it is mostly just age. New fuse panel, cleaned up ignition >> switch, lots of dielectric grease. However, I was wondering about the >> regulator/rectifier. To my knowledge, it's function in simple terms >> is to smooth out the electrical current generated by the alternator >> and make sure it is a standard voltage (I know it's more complicate >> than that, but let's keep it simple for my benefit). My question is >> what happens when it goes bad? Does it simply fail outright or can it >> gradually degrade and do it's job less efficiently? If this happens, >> what kind of symptoms would I be seeing on my bike? If it is allowing >> too much current or not enough, would this strain the overall >> electrical system on the bike and lead to problems? I am leaning >> towards replacing it anyway, I am just curious as the cheapest one I >> have seen so far is $135.00. How can I test the original part? >> >> Thanks! >> >> MN Blue >> > > > > > -- > You received this message because you are subscribed to the Google Groups > "Nighthawk Motorcycle Lovers!" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<nighthawk_lovers%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/nighthawk_lovers?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en.
