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Lindeman crawler fan
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2,704 Posts
Discussion Starter #1
I need some help !

I was told this is a Dynamo of a Kubota that I'm using on a special tractor I'm building.
I got it and a voltage regulator of ebay and the guy said they were both in good working condition.

The regulator has three spade terminals in this pattern:

1 - - 2 ( the #3 terminal is centered below the top two terminals )
3 -

He told to hook the two wires from the Dynamo to the top two spade terminals, (1 & 2).
The wire from the bottom spade terminal (3) goes to the Amp gauge.

The Amp gauge is not reading anything.
If I was getting current out of the regulator, I should be able to disconnect the positive battery cable while the engine is running and it should stay running.
The engine shuts off as soon as I disconnect the battery cable.

Do I have this wired correctly ?
How can I check to see if the Dynamo is putting out current ?

I sure would appreciate some help with this.



 

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Machinery enthusiast
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4,257 Posts
Ray, I'm rushed for time this evening but will try to help you cipher later (if no one else knows in the mean time). Heres a schematic of my BX23's electrical system that uses the dynamo and electronic regulator. Later I'll take a look at how many wires it actually has but according to the schematic it has more than 3.
The dynamo should make approx 22 to 32 VAC on it's own without any reference DC voltage as it uses permanent magnets for the field, kinda like how most small L&G engines do.
I believe it's rated @ a max of 15 amps.
Hopefully the schematics will help.
Let us know.
Dave
 

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Lindeman crawler fan
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2,704 Posts
Discussion Starter #3 (Edited)
Thank you for putting up the diagram, Dave.
Unfortunately, it really doesn't help me any as it is very different from what I have. .. Sorry ..


After looking thru ebay tonight, I think I have the wrong regulator.

I found a regulator rectifier used on early model Kubota compact tractors with permanent magnet alternator without "no charge" indicator light.
Is this the regulator that I need ?

Here is the ebay link:

http://cgi.ebay.com/ebaymotors/ws/e...0541017881&viewitem=&sspagename=STRK:MEWAX:IT
 

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Lindeman crawler fan
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2,704 Posts
Discussion Starter #4
Took my test light and clamped it to a good ground.
Then I touched the point to one of the wires on the Dynamo .. nothing.
Touched it to the other wire .. still nothing.
So I clamped the test light to one of the wires and touched the point to the other wire and it lights up nice and bright.

With the Dynamo putting out current, the problem has to be with the regulator.
I went ahead and bought that regulator off ebay.
It has the same color wires and the same style connectors as the Dynamo so figure it is most likely the right regulator.
 

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Machinery enthusiast
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4,257 Posts
Good test, if you had read anything out of that dynamo referenced to gnd it would be bad :D
About the only things to go bad w/them is the bearings and you can tell easily if they need replaceing.
I should be able to peep out my regulator this evening and I'll post the findings.
I do know from past postings that it has to be properly grounded or it either won't put out or charge very intermittently.

Dave
 

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Lindeman crawler fan
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2,704 Posts
Discussion Starter #6
Thanks Dave

That is good information to know on the Dynamo.
I noticed that this regulator that I'm getting has a separate wire that attaches to a ground.

The one I currently have on the tractor does not have a separate wire going to ground.
Maybe that is why it does not work with this Dynamo ??

When I was looking thru ebay for a Kubota regulator, they were all for the newer tractors and had the 6-terminal connector like you're diagram shows.
The one I bought is the only one listed for the older tractors and just has the 2-connectors for the Dynamo wires, 1-hot wire and 1-ground wire.
 

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Machinery enthusiast
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Ray, as we figured my reg is a 6 wire. Good news is that there isn't a large Bat wire from the reg to the battery, all the wires are the same gauge.

My guess is that the red wire off of the reg should go to your battery (thats how the schematic shows it on my BX23) and if you're running a ammeter you want to take it through it before you take it to the battery. I'm also thinking that it may need to run through an on/off switch but of this I'm not sure. It doesn't on my BX23 but thats because theres another reg lead that comes off of the "on" terminal of the key switch, (the RY lead).
The 2 blues probably go to the dynamo and for kicks don't ground that black wire just yet, leave it loose.
On my BX23, there is a black wire that comes out of the tractors wireing harness and it grounds on one of the reg's mounting bolts. There is no wire coming out of the reg going straight to ground, at least not in the vicinity of the reg. I'm guessing that your reg's black lead "may" either be the idiot light lead or the "on" lead but I'm not sure. (the schematic shows the reg gets it's ground through case ground on my BX23).
On my BX23, there is a lead that comes out of the reg, goes through the idiot light then on to ground (the WR lead).
Operation of my BX23 seems thusly, hopefully we can use it to cipher yours.
1) with key off, theres battery voltage sitting on the reg's R lead but diodes internal to the reg keeps it from discharging.
2) w/key switch on, battery voltage is applied to the RY lead, winds it's way through the rectifier's diodes and out the WR lead through the idiot light (lighting it up) and on to ground.
3) with engine started the dynamo's output voltage is higher than the battery voltage which changes the bias in the rectifier portion of the reg, which causes higher voltage/current flow out the R lead to the battery. It also turns the charge lamp off.

So with that said, that black lead "may" either be the switched battery voltage lead or the idiot lamp lead. Bad thing is the setup probably won't charge until we "gamble" on what the black lead does.

Dave
 

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Lindeman crawler fan
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2,704 Posts
Discussion Starter #8
Thank you for this information, Dave.
I appreciate you taking the time to help me out here.

The listing on ebay shows a paper drawing of the regulator with the wires labeled.
It isn't clear enough on the listing to be adle to read but I'm assuming the drawing will be in the box with the regulator.
 
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