Hello, John Talley here with partzilla.com. Today we're looking at the
charging system on our 2007 Yamaha Grizzly YFM 700. Seems that this one is
not keeping the battery charged up. And what we're going to be looking at
specifically today is the regulator rectifier, which is tucked away right
there. What it does it takes the AC signal that comes from your stator,
converts it into a DC signal, which then charges your battery and provides any
power for anything you happen to be running on your machine. You're only
going to need one specialty tool and that's going to be a good digital
voltmeter. Just make sure it has that little symbol right there which is for a
diode. And what we're gonna do is actually unplug it on the unit and test
each point as far as we can going from the positive and the negative, which goes
to your battery, and then also what goes to your stator. And what we're going to
be looking for in there are a set of diodes and what we're going to do is
called forward biasing them, and we're going to be taking basically a voltage
measurement across each diode to see if it's doing what it's supposed to do. So
let's see what's going on with this one.
So what I'm gonna do is go ahead and pull it all the way off, bring it over to
the table, and then I'll show you how to do a static test on it. There's only a
couple of ten millimeter bolts mounting it to the frame. So we've already done a
voltage test on the battery. We know it's in good shape, but it's just not charging.
Because when you crank it up with the meter still going across the terminals,
it's still reading actually a little bit less than the nominal voltage, so that
means it's losing voltage. There's just a clip on either side you have to push in.
Alright, let me show you a picture of what we're going to be doing. You've got
a network of six diodes, and what we're wanting to do is check those to see if
we can forward bias them on either side. So what we're going to start with is
putting our positive over the negative output of the voltage regulator. Then use
our negative one and go to each one of these winding wires and that is going to
forward bias these three. We're then going to reverse it.
We're actually going to put our negative lead on the positive input going into
the voltage regulator rectifier. And then we're going to take our positive lead to
go across those same three windings to test the forward bias of these three
diodes. Sounds complicated but it's really not. So take your meter, switch it
over to diode. This is the positive, this is the negative. So let's start with
putting this over to the negative, and we're gonna take our negative lead and
forward bias the first three diodes. And we should have around point five volts. Now,
we want to make sure that it's stopping current. We will reverse the leads and that
should read OL going across. Nothing, nothing, nothing.
So those first three check out. Now, let's do the other side.
This should forward bias the other set of diodes.
Alright, well look at that. It forward biased, but it's only 0.13 volts.
.13. Hmm. Point one three. So what's going on there? Is there
something wrong with this one? Have we found our problem? Just for fun,
let's do the same test on the brand-new one. Point one two four. So, unless they're
both bad, why did we get that reading like that? Well, I think I can explain why.
Positive here, forward biasing back had no problem. It was going against that
gate so we were only reading those three diodes. When we were going the other
direction, we were actually paralleling a forward bias diode here in whatever
circuitry they were using inside of the regulator on the other side. So it's easy
to go in and read the forward bias across each one of these diodes, but
guess what? When you try to forward bias these you're also trying to forward bias
these different transistors down here. So it's going to give you a different
reading other than the 0.5. So, what have we learned here? Well, it turns out you
cannot do the same diode test on every single manufacturer and expect the same
results because the internal circuitry is going to be different going from one
manufacturer to another. And we were able to compare it to a new one to determine
that this one was okay. Are you going to go ahead and buy another one of these
just to do your testing? Probably not. So here's my advice. Check your battery
first. Then, go check the output of your stator. That's going to be critical to do
a dynamic test. We actually have a video that shows you how to do that. And by
process of elimination, it's probably going to be your regulator rectifier. So
what you're actually looking for is to make sure nothing is shorted to ground
inside of your regulator rectifier. Second thing you'd like to see some type
of forward bias. Some of a maybe 0.5, some of them may be as low as .1,
but you want to see some type of change. It's really a process of elimination. I
mean, I'm sure that this is a good one so we're gonna put it back on there and
what I'll do next is actually look at the stator to see what's going on with
it. So, that being said let me go get this one back on the machine. Whenever
I'm working on an electrical systems particularly on a side-by-side or ATV, I
want to pick up a tube of dielectric grease, because this will help with
connectivity, plus it'll keep out any water or dirt. Now, I realize it's got a
seal in there, but this just is an extra layer of protection. Go ahead and plug in
our stator first. Push until it clicks.
Now we just need to bolt it back up. Well alright guys, normally this is where I
would tell you "hey we've just wrapped this one up." Well,
we can't wrap this one up because it still has a problem. Now I feel confident
the regulator rectifier on this unit is still working, but what I need to go look
at next is the stator. So if you would, follow me over to that video and we'll
see what's going on with it. Listen, if you do need parts for your
machine, why don't you come see us at Partzilla.com and we can get you taken
care of. If you like what you see why don't you hit that subscribe button below. That
way you can keep up with whatever I'm working on next. Also, if you want to take
a deeper look into regulated rectifiers and the stuff we unearthed here, why don't you
check out that video where we really give a good explanation in between the
difference of the units for each manufacturer. Listen, we just want to say
thank you for shopping here with us at Partzilla.com and we will see you in the
next video. Have a great day.