Stator Outputs to Rectifier, 1991 135-HP

dogsdad · Mar 7, 2004

Okay, back for more... I think I fried my rectifier by not paying attention to the polarity of the battery terminals when I was absent-mindedly installing the battery the other day. Duuuuhhh! Anyway, after that I noticed my voltmeter on the instrument panel saying 12 volts, engine running. A voltmeter at the battery terminals confirmed that. Bad, bad, bad. So, I get to looking at the charging system. DC measurements of the rectifier dodn't look right... I ended up thinking my stator might be toast. So I ran the motor with the stator wires disconnected from the rectifier to see what the stator puts out. My multimeter says about 15 volts DC from one of the yellow wires and about 6 volts DC from the other yellow wire (both with respect to ground). Hmmm... So I drag an oscilliscope out there, and I see an AC waveform on both yellow wires coming from the stator, but the amplitude of one of them is about a third of the other---confirming that my multimeter wasn't lying to me. Question: shouldn't both stator outputs be equal in amplitude (voltage) with respect to ground, or is that not an issue because of the fact that we're dealing with AC? Is my stator ruined? -dd-

clanton · Mar 7, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Im not sure about the scope, but the multimeter should be connected between the 2 yellow wires, AC scale, the results X 1.414 should give you peak voltage. Peak voltage about 18 at 1500 rpms is a guess, I dont have specs for that engine.

dogsdad · Mar 8, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Clanton, thanks for the input. No pun intended! As I look at the wiring diagram, things look both clearer and stranger. I find it very odd that I have two different AC signals on two wires that are the same color---the two yellow ones going from the stator to the rectifier. In my world (I'm an electronics tech), that would tell me to expect two identical signals...and if they are supposed to be different voltages, which one goes where? And why does one go to the voltage regulator---is it a reference for the regulator, and if so, why is that wire the same color as the other?? Does anyone know of a good diagram of the charging system that gives good details on the rectifier and voltage regulator? I want to see diodes and all the detail. Thanks! -dd-

rodbolt · Mar 8, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

DUDE shame on you. no manual. as a former electronics tech myself, and yes I have smoked the requisit amout of circuit cards and such to be a tech.

. I cant belive you would be using your crank skinners with no service guide. its a simple altenator. it has magnets in the flywheel and a coil of wire called a stator. the wires are smoke filled. if the smoke isnt let out it works. we need to know which system you have. it could be a 16 amp which has a seperate regulator rectifier or a 40 amp system that uses a water cooled regulator/rectifier. all the tests you will ever desire are in manaul # 90-816249--1. dont check an AC circuit to an engine ground. you can check for shorts to ground but not output to ground. you should also know that a stator output is always AC until rectified. the service manual is fairly clear on the diagrams. post which system ya have and we can see what happens. people look at how one person tests and then they try it. that is why I am trying to point out how things work and why.the battery charging system really does not require any peak reading or ocilliscope equipment. just use the diode function to test the rectifier (its a full wave bridge) and a AC digital to test for output from the stator and the Ohms function to test the stator battery charging coils for shorts to ground. the stator also has the charge coils for the ign circuits. leave that part alone. good luck and keep posting

clanton · Mar 8, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

I wish I could make this thing draw. The 2 yellow wires are the ends of a set of windings. I missed the model, year and HP of engine. I can you a diagram, if I have diagram for your engine. edited:I see the engine info now.

dogsdad · Mar 8, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Actually, I have a manual, but it's a Clymer. The wiring diagrams show lines between pictures of of the parts involved...and I want schematic symbols! For instance, it is very helpful to know what type of rectifier you're dealing with, otherwise an ohm meter is useless. I resorted to the oscilliscope because in my travels I have found that it tells a lot more than any multimeter can, at least where voltage is concerned. I prefer to use an o'scope any time I can. Contrast that to what I've seen many so-called electronics technicians doing---measuring digital signals with a multimeter (I kid you not!). With an o'scope, I've always found it much easier to figure out how things work...and why they AREN'T working when they should be. Anyway, I'd sure like a good diagram that shows EVERYTHING in detail. Part of the confusuion on my part is that I have no diagrams showing what everything is referenced to...and that can make things pretty damned confusing! Maybe once I figure all this out I'll make a schematic of it and make it available to others...but I don't think anyone should start holding their breath yet! -dd- PS: I have a 16-amp stator. I found a note in my manual that says the 40-amp version of the 135 has a different flywheel cover with grooves on it or some such.

roscoe · Mar 8, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

I have absolutely NO electrical knowledge or experience, with the exception of getting zapped a few times. But it seems to make some sense? to me, that one yellow wire would deliver higher AC volts, which are rectified to approx 14 volt dc for battery charging. And the other yellow wire would deliver approx 6 AC volts, which are rectified and regulated to produce 5v dc for the accessory circuit. If this turns out to be true, I'm gonna have to buy myself another musky lure.

rodbolt · Mar 8, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

hello oh well muskey dont get no lure's

. anyway muskey. on a two wire stator, that is common to a lot of outboards, its just the bitter ends of a coil of wire. pass magnets around a coil and you get an A/C voltage. also called a sine wave. you cant read one wire to ground. the two wires are taken to a rectifier, a rectifier is a rectifier. all they are is diodes. the clymer manual is fairly specific on how to test it. the 16 amp system uses a rectifier that merc has used many many years and many applications. anyway test all the functions as per your clymer but the factory manual actually is very good on the electrical and ignition for that motor. good luck and keep posting

jimmy@wm · Mar 8, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Hello DD,I have a manual Merc manual I bought for an '87 150 it covers the V-135 thru V-225 for ser #'s U.S. 5464486 and up. It is pretty detailed in the trouble shooting for the elec systems.If your rectifier is the one that resembles a cube with 3 terms on it, it is a 16 amp.I just replaced one on my motor. It's a basic full wave bridge with the mounting part of the base being the neg output side of the DC. If you would like and would be of any assistance to you I can try to scan and send some of this info to you . As far as your stator I'm pretty sure your's is ok.It's a standard 2 wire alt that should be checked without a ground ref to the engine. Good luck. Jimmy

dogsdad · Mar 9, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Rodbolt says the stator wires are just the ends of an inductive coil in the stator assembly...and maybe that's true. BUT, if that coil is tapped amd grounded, then a ground reference is meaningful. With some rectifier configurations, you MUST have a tapped coil. So, not knowing exactly what these components are is a real handicap. I am somewhat convinced that the charging system coil in the stator is tapped and grounded, but I really would like to know for sure...WITHOUT having to take the thing apart. Roscoe, I think you're close to being correct, but both wires of the stator output are rectified for charging the battery. BUT, the two AC outputs of the stator, go other places as well, and one of those places is indeed the instruments via the throttle/remote control assembly. What I need to know is which one---the 6 volt, or 15 volt? And why would they color the two wires the same if the outputs are different? Could be my stator is hosed, I guess, and it's not supposed to do what it's doing. I'll have a new rectifier soon, and when I install it I'll get to see if there's any improvement to the system. -dd-

jimmy@wm · Mar 9, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Hi DD, I don't want to sound offensive so please don't take it that way. I am also an elec. tech and think you may be thinking a little too complicated for this setup. I just purchased a new stator from cdi as well as the rectifier. All the stator battery cgarging coil is is a simple coil passing over magnets to create a voltage, the stator I purchased had a built in reg and none of the test are supposed to be taken with a ground ref,except for the rect. The setup is really quite simple for these engines. Again, not to be offinsive. Ji

mmy

dogsdad · Mar 9, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Jimmy, no offense taken! Thing is, I'm one of those people who just has to KNOW. I've never been one to just replace a part and be happy that it works (or PO-ed because it doesn't)...I always want to know why! At this point, I want to know for SURE how the stator coils are configured, and I want to know exactly, without any doubt whatsoever, what the rectifier setup is. I want to see the diode arrangement. It matters. -dd-

roscoe · Mar 9, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

rodbolt-- I'm getting some lures anyway.

GanderMountain Outdoor Sporting goods store just remodeled. It went from 20,000 sq ft, to 90,000 sq ft.

Poorhouse, here I come.

jimmy@wm · Mar 9, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Yeah DD,I know I'm one of those same people,although some time it's a lot more trouble than it's worth. As far as finding the actual configuration of the rectifier and coils you may be able to contact one of the engineers at cdi, who made the stator and rectifier that I bought. The rectifier looked exactly like the one I took off. The stator looked very different because it wasn't covered in the black potting material that the original was which I think would be better because of less heat buildup but the configuration of the coils should be the same.Also came with 2 yr warranty. Hope this helps and good luck.

Jimmy

rodbolt · Mar 9, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

hello dude ya cant tap an ac generating coil to ground. you can tap them together to make various phase charging sytems. your way out on the wrong track. follow your service manual. test the yellow wires for grounds. as far as the ac going everywhere is really is only supposed to go to the tach via the gray wire. the tach is an ac drag cup type instrument. I tried to tell ya how the system works. no offense but your way off base. its a very simple system with very simple tests that is easy to test. its not a 3 phase sytem or anything. post which manual you have and I will see if I can find the page # to reference you to. good luck and keep posting

dogsdad · Mar 10, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Rodbolt, I'm not too sure what you mean by an "AC generating coil". I envision the stator coils as being essentially the secondary coils of a transformer. If you think back to some of the simpler power supplies, try to remember the full-wave rectifier configuration...two diodes, each with its anode tied to one end of the secondary, and with their cathodes tied together for the full-wave output. If that secondary winding is not tapped, the thing will not work because each diode will prevent the other from conducting any current. To be perfectly honest, I was misleading myself about how the full-wave bridge works. I was thinking that it needs a tapped secondary, but when I sat down and drew it out, I saw my error and I remembered the circumstances that require a tapped secondary. I know that some have already said that the rectifier is a full-wave bridge. But is it really? If it is the configuration that has four diodes, that's one thing...but if it's just a full-wave rectifier, that's something else entirely. It's difficult to know when someone posting is giving the real skinny. Many want to be helpful, but just don't really know for sure but will tell you something anyway. I know that you've seen it yourself. That's why I asked very specific questions. The upshot of it is, I think my stator has a shorted coil, IF indeed the rectifier is a full-wave bridge. I saw definite and consistent differences between the two wire's outputs, and I know what it looks like when you try to measure a voltage that isn't referenced to ground. -dd-

rodbolt · Mar 10, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

hello by your tests from a yellow lead to ground I am inclined to belive that you may have a winding problem. test each yellow lead from the lead to ground, should read infinity on both leads. if it reads infinity and passes the lead to lead resistence spec I will bet its ok. the stator test is a simple diode check. if you dont have a manual say so and ill try to post the test procedures. you are working with an alenator. not a transformer. keep remembering and it will come back. there is a lot that I have forgotten as well. sometimes I pick up one of my A school or C school books and think man did I really do all that good luck and keep posting.

dogsdad · Mar 10, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

Haha! I know exactly whatcha mean about those A and C school books, Rodbolt. I musta been a lot smarter when I was 20 than I am now.

Seriously though...I thought all the stator is was an array of coils, and that there are magnets rotating there and inducing current flow. ??? Have I been misinformed?

I am certain, however, that a coil does not care what is generating the magnetic field that is acting on it. All it wants to see is lines of magnetic flux and relative motion. That could be provided by a primary coil with AC running through it or a magnet in motion relative to it (the coil). Right? And YES, I believe that I measured the resistance of the yellow leads to ground and got a big fat zero on both (that's where I got the idea that the coil was tapped to ground in the first place---if I am correctly remembering all the different things I did). I think I'll start all over again fresh this weekend. I've looked at so much so many different ways that I am not real sure what I've seen anymore!

rodbolt · Mar 10, 2004

Re: Stator Outputs to Rectifier, 1991 135-HP

hahahah sounds like a plan. anyway there are 6 magnets in the outer rim of thge flywheel that pass around the 2 ign capacitor charge coils and the battery charging coils. the battery charging coils are just a coil of large wire and should have infinite resistance from both end leads to ground. the rectifior is a simple 4 diode bridge full wave. they only cost about 30 dollars at the napa stores. and sierra parts give a year warrenty on electrical parts and merc gives 90 days.your stator may be avalible from sierra as well should it turn out that you need one.carefully test all the functions but dont go to deep. its a simple single phase altenator. not like some others that use a three phase. good luck and keep posting. and remember keep the smoke in and the rest is PFM

Stator Outputs to Rectifier, 1991 135-HP

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