Kubota B7100 Regulator/Rectifier P/N

[tmfs]

Can anybody point me to the p/n for the regulator/rectifier for a B7100? The tractor is around a 1980-81 model. I've been working with the dealership but they have aren't confident about it but tell me that once they order it I have to pay for it and can't return it.

I don't know if this is significant, but my tractor only has 2 wires coming off the dynamo (unlike many of the schematics I've seen). Alternatively if their is an bolt on alternator upgrade I could do I'd be interested in that also, but everything I've seen thus far looks like it would require hood and side panel modifications.

Thanks,
TMFS

 

[birddogger]

Yeah, 2 wire dynamo. It is a permanent magnet alternator.

Is it not charging? I'd check the fuses first. Someone almost sold the boss a new alternator when I intervened. Found the blown fuses. 2 fuses and it's fine.
Don't forget, use ~ (ac) on the meter when checking dynamo. If is is like our B7200 the regulator/rectifier is on a cross-bar behind the dashboard/console, just left of the steering post. Maybe yours still has a part number visible. The fuses were in a couple inline fuse-holders in a bundle of wires near the clutch safety switch.

 

[tmfs]

Thanks for the reply birddogger. Yeah, its not charging. I'm pretty sure its the regulator. I've got something over 30V out of the dynamo (at max RPM) and all the way through to the input bullet connectors on the regulator, but nothing on the output side. I do have the regulator out (sorry, no P/N). IIRC, the service manual says to check the rectifier/regulator by measuring for continuity in one direction only. I'm pretty sure this means that I should get continuity from either of the AC inputs to the POS output, but I don't.

That said, this tractor has a long and sordid history leading to several wiring issues I have yet to work out. As I type this I'm thinking of a few additional things I should do first before I plunk down the $ for a new rectifier/regulator. If anybody can clarify the bench test for the rectifier/regulator that'd be good, but I probably still need the P/N if anyone has it.

Thanks again,
TMFS

 

[birddogger]

I wish I knew the internal block schematic for the rectifier/regulator. If you know the dynamo inputs and the DC outputs from the diodes (rectifier) you should find continuity from each AC "in" to one of the dc 'out', then reverse the meter leads and it will show continuity from the AC "ins", to the other dc out.
But if there's any true regulation going on inside that will not happen. It has to be "ON" to have regulation happen. Try isolating all the DC outs and check for voltage rather than continuity (running of course) if the dynamo puts out ~30 V then there needs to be regulation to keep that from boiling the battery dry.
Oops saw you did the voltage check. If I remember one of the fuses actually fuses the regulator. It gives the ground reference, no reference and the regulator shuts off. Lemme see if I can find a wiring diagram.

 

[tmfs]

Yeah, the internal schematic would really help. I've considered tearing into it to have a look, but I'm saving that option for now. I didn't have time to do anything last night, but I have the regulator in hand right now. There is definitely no fuse on the ground as that wire goes directly to a ring terminal and gets grounded to the frame. Other testing with a multimeter confirms that all the wires/connectors on the regulator are good. I can really only see 3 scenarios at this point:
1) Bad regulator
2) Bad Dynamo - I know the dynamo can supply ~30V no load, but what happens when a load is applied? I'll see if I can track down a couple 10ohm power resistors so I can load test the dynamo.
3) Regulator needs a battery - Another post I read somewhere indicated that you needed a good battery hooked up to the regulator for it to turn "on". Due to its "sordid history" the wiring between the positive output of the regulator and the battery needs some work. I've yet to look into this.

Tonight I'll also post the test that the service manual recommends and my results. I'm still pretty certain its a regulator problem, but I appreciate the suggestions. Nobody cares to drop cash on something only to find out that wasn't the problem.

 

[tmfs]

Ok, I do have some more info...

The kubota workshop service manual has the following test (quoted word for word).
Procedure
1) Check for continuity across tow of the four terminals.
2) One-way continuity is o.k. If continuity exists both ways, replace the diode.

Reference Value
O.K. there is one way continuity
Brown (AC) <-> Red (B)
Brown (AC) <-> White (E)
Red (AC) <-> Red (B)
Red (AC) <-> White (E)

Trouble is, the 2 AC inputs on my rec/reg are green, the POS output is red and the ground is black.

I think I have a pretty solid line on the regulator. It did actually have some numbers on it that I originally discarded since they didn't match the kubota p/n format I expected. The numbers on my regulator were RS1104. I think this is now an obsolete p/n replaced by 15372-64600 which was replaced by 15372-64602 (current). So, there you pretty much have it. Not 100% sure yet that mine is no good, but leaning that way.

Thanks,
TMFS

 

[birddogger]

Wasn't able to sneak the manual out of the shop yet. I'm gonna have to wait till the boss makes a run to the feed store.

I think the dynamo should be OK, it is just a couple magnets and coils of wire. Unless it was struck by lightning or wired straight across the battery to melt the coils.

 

[Dave_eng]

Can anybody point me to the p/n for the regulator/rectifier for a B7100? The tractor is around a 1980-81 model. I've been working with the dealership but they have aren't confident about it but tell me that once they order it I have to pay for it and can't return it.

I don't know if this is significant, but my tractor only has 2 wires coming off the dynamo (unlike many of the schematics I've seen). Alternatively if their is an bolt on alternator upgrade I could do I'd be interested in that also, but everything I've seen thus far looks like it would require hood and side panel modifications.

Thanks,
TMFS

Go to Kubotabooks.com and download the B7100 WSM for free
Charging circuit is on page 310. The two wire dynamo's output is 10 amps max.

There was an optional dynamo with 35 amp output.
Dave M7040

 

[85Hokie]

Go to Kubotabooks.com and download the B7100 WSM for free
Charging circuit is on page 310. The two wire dynamos output is 10 amps max.

There was an optional dynamo.
Dave M7040

Dave.......this post is almost 6 years old - I hope the op has fixed it

 

[Dave_eng]

Dave.......this post is almost 6 years old - I hope the op has fixed it

Your are correct. I think what happened is that someone on another thread posted a link to the old thread and that is how I got to the old thread.

Thanks for waking me up.

Dave M7040

 

[85Hokie]

Your are correct. I think what happened is that someone on another thread posted a link to the old thread and that is how I got to the old thread.

Thanks for waking me up.

Dave M7040

Hey - no problem, I 'd like to have a dollar for every post that I have responded to, a day late and a dollar short!

 

[Crashcage]

Your are correct. I think what happened is that someone on another thread posted a link to the old thread and that is how I got to the old thread.

Thanks for waking me up.

Dave M7040

Hey Dave,
Used my tractor the other day,charging light came on.Lifted the hood and the battery was boiling!Previous exp with motorcycles says reg/rectifier.
Downloaded 3 different manuals,wsm's and all are different!
Going nucking futs here!Cant find a wiring diagram that coinsides with what i have.Where do you suggest i look for a reg/rectifier to fit?
Also,i have the reg/rect but there is another box....Do you know what this might be???
I need more post to load photos.

 

[Dave_eng]

Hey Dave,
Used my tractor the other day,charging light came on.Lifted the hood and the battery was boiling!Previous exp with motorcycles says reg/rectifier.
Downloaded 3 different manuals,wsm's and all are different!
Going nucking futs here!Cant find a wiring diagram that coinsides with what i have.Where do you suggest i look for a reg/rectifier to fit?
Also,i have the reg/rect but there is another box....Do you know what this might be???
I need more post to load photos.

I think after 5 posts you can add photos. Just generate a couple more comments on another thread and you will be good to go.

Suggest you start a new thread about your current problem.

I cannot tell what model of tractor you are talking about.

Some tractors with series wired Glow Plugs had an additional electrical coil in a metal box.

Will be watching for a new thread from you.

Dave