Kohler 18.5 KW diesel

[Boss]

Image no longer available , link removed due to spammers
This is a genset I'm working on, mostly learning as I go.
I found that the 18.5 KW generator exchanges  feedback with the automotive style alternator attached to the governor controlled diesel engine through a controller board. To automatically increase power output from the fixed speed engine,  more excitation voltage/current is fed to the alternator which in turn increases the excitation voltage/current to the  the main generator.
Anyway, here is the controller which not only is an antique, it is also not functioning

Image no longer available , link removed due to spammers

I found a place which may rebuild it, I thought about troubleshooting it a little, but I do not have a schematic, just the service manual from Kohler, which doesn't cover the controller at all.
The controller uses ferrite doughnuts like a clamp-on amp gauge to sense.
 Following the service manual we manually excited the main generator field and that worked, it put out power to the mains(two phase 115 is what it is wired for at the moment.) 
I thought maybe I wanted this because I am a home-brew fuel man; I process 25 gallon batches of biodiesel in a Apple-turnover (upside down modified electric hot water heater, originally designed by Girl-Mark as the Appleseed biodiesel processor)
But 27 horse power diesel? It is too much, if I could make this 18.5 KW generator charge my battery bank in fifteen minutes that would be cool, well I'm sure some one will chime in about ultra fast battery charging, but rest easy, it was a pipe dream anyway.
Then in another lie-awake-nights, wish I was really dreaming kind of affair, I thought, could I get a controller that would instead of getting feedback from its own output for voltage correction, why not use the grid? I wrote about that back in February or march, and it is one of the more popular pages on my site, even though I've received no feedback, interesting tags, I guess.
what do y'all think?
Image no longer available , link removed due to spammers

[TheEquineFencer]

I was looking around the site and found this posting. What did you ever do with the generator?

[Boss]

It belongs to a friend of mine. It is still sitting right where it was in that photo; outside my shop. I don't know what he wants to do with it, I like the little diesel engine
Brian

[TheEquineFencer]

Is it a brush type generator end? Not meaning to be insulting, but that means does it have brushes that run on the rotor? if it does have you tried flashing the feild? I asume it runs but the generator end does not put out. Is this correct?

[Boss]

yes brushes on the generator
Yes we flashed the field
We did most every test in the book. At one point we forced it to make power, but on a final test fogot to disconnect a feedback circuit and it made the bad smoke on the controller

[TheEquineFencer]

I just went back and looked at the link, The engine alternator does not control the generator voltage. It uses the engine alternator to see if it is running if I remmeber correctly, some old ONAN's were like that. Crank it and see what voltages you have on the wires that go to the controler. See if the engine alternator is charging. If it is the engine alternator may still be bad on the section that controls the generator safety functions. I'll look around and see if I can find a diagram in and old generator manual when I move everything back into my shop. I hada tornad come through and everything kind of a mess. I think the engine generator actually gives it a ground or a hot to the controls for it to stay running. Send me the DATA PLATE INFO and I'll see what I can come up with. This is an old school geerator, if the rotor and stator are OK, A/C output when the feild is flashed, you can wire around the problem areas and do it safely and still have it work as designed. I've used an oil pressure switch to replace the overcrank sensor in some old generators. The "sensor" is built into the governor actuator, $1900.00 to replace the governor in an older ONAN. $2.99 from NAPA for the switch, which would you do? I'd get the engine alternator checked out by a real service shop and check the "extra" wires that are on it for an output voltage or ground when it's started and run. Check the generator Hz and voltage output  with it running if you can. I wish I were closer, I'd run over there and fix it for ya.

[TheEquineFencer]

http://www.fwmurphy.com/product_search/?p=mgc547 check out something like tis if you need to replace the controls. Also look at the home site they have for more info. I've used an older version of this to replace controls on some Kohlers.

[Boss]

Very kind of you and thoughtful information. It'll take some time for me to assimilate (sorry, we've been watching Star Trek SG)  all this, Good to know there are qualified techs on these old school gennys
 

[TheEquineFencer]

I love Star Trek Any Generation. If you can, get some info from the engine alternator too. I think you may have a simple problem. Let me entertain your attention a bit. Most generators like you have are a basic mechanical engine with a mechanical governor. Some have an electronic governor. When you start the generator ussualy there's a circuit that excites the rotor to start the A/C output. Usually there's something that let's the generator know it's running, like an Aux. output from the engine alternator. If it does not see this it shuts down after it tries to start a few times on Overcrank or Failed to Start. Sometimes you get lucky and the control panel has a wiring diagram inside it, but not too often. If you look at the Engine Alternator wiring and run the wires out to see what and where they go you may find your problem. Check the wires on the Alternator with a Digital Multimeter and see what you have on each wire. Check it for DC Voltage as well as A/C voltaage, then check them to see if they get a ground. Check them with it running and cut off. When you flashed the field, did you check to see if you flashed it with the correct polarity? If not this can holdit from working right. Check the wires going to the rotor with it cut off and with it running, figure out which is B+ and B-. If you flashed the feild and did get A/C output, then the generator end is good if it put out unregulated A/C. if you hold the Flash circuit too long with too high of a B+ input you can smoke things. I've seen them put ot 700+ VAC when someone did it wrong. At that voltage it can pull an arc to something just like high voltage. Be careful. Check the Voltage output from the generator when it cranking.

[bergmanj]

For a really good troubleshooting resource go to "SmokStak" website and to it's Kohler forum.  Also very good forum on Onan's & others.

I've used and contributed to it many times - extremely helpful on generators.

Regards,   JLB

[TheEquineFencer]

Excellent suggestion. You'll be able to find someone with a wiring diagram in there if you're lucky. That would take a lot of guess work out of troubleshooting it. If you really get fed up with it you could strip every control off it and just install a Murphy Control panel.

[Boss]

If you flashed the feild and did get A/C output, then the generator end is good if it put out unregulated A/C. if you hold the Flash circuit too long with too high of a B+ input you can smoke things. I've seen them put ot 700+ VAC when someone did it wrong. At that voltage it can pull an arc to something just like high voltage. Be careful. Check the Voltage output from the generator when it cranking.

Hey how did you guess that happened?
We determined it was the main circuit board and not just because we smoked it, it wasn't doing what it was supposed to do before that, the smoke was icing on the cake. It was frustrating that the super thick factory service manual did not have a schematic for the most important component, the controller board. I'm rusty with component level circuit board troubleshooting, but I can still do it, but I need the real schematic, not a funky block diagram.
Anyway I think the owner lost interest, and I have bigger fish to fry at the moment. Seems like life is getting crazier than ever lately.
Did I post the BMN about the bear getting in our house last week?
BMN (Brian's Morning Newsletter) can be read and commented on at http://outfitnm.com