jmct
I am new to this forum, hopefully someone can point me in the right direction. I traded for what I think is a late 1990's SG015, LP fuel, rated 15kw, 120/240 generator. It only has 220 hours on it. I hooked up an LP bottle right after I got it and the engine started immediately, but would surge for a few minutes then die. It would start right back up and do the same. The exhaust smelled a little rich so I figured I wasn't getting enough gas to it thru the little 20lb LP bottle and gas bbq grill regulator I was using. Or I just needed to get a load on it to get smoothed out a little.

I didn't test any voltages or anything at the time: I was mainly making sure the engine wasn't froze up.

I finally got around to flushing the coolant and changing the oil this weekend. The oil filter was marked "aug 2004" but the oil was golden clear and the radiator fluid I drained out was just as pristine. Things were looking really good.

I got the generator set in place and wired into the generator input on my Xantrex XW6048 inverter/charger. I am off-grid with a solar/battery/backup-genny system, and I've been getting by with a $500 Harbor Freight 6kw unit until the rear bearing went out on it a week ago (kinda motivated me to finally get that Generac going...).

I fired up the the generator (still surging, but still on the 20lb bottle and bbq reg) and checked out the Xantrex to see what kind of juice it was getting. Kinda disappointed to see 0 volts on both legs.

I checked the gauges on the Generac control panel and they showed the same: 0 volts, 0 amps. I opened the panel and started checking: nop valteg at the two circuit breakers, both fuses good, red LED on the PCB in the back comes on when the RPM is at the peak of the surge. Interesting: no LED's lit at all on the voltage regulator. There is a 2.5" long cylinder that looks like a fuse in front of the bottom of the PCB: the bundle of blue wires had rested on it and one had melted into it. I pulled it clear and taped it but it made no difference.

Anyway, it looks like I am not getting any excitation.

I have tried to find manuals on this unit online but it is almost like Generac never made it.

Here are the model numbers from the nameplate. I also have pictures of everything if it helps.

MODEL 97A07690 S
TYPE SG015-A1161.6V18CDYNC
DESCRIPTION ASSEMBLY
GENERATOR A2114
CONTROL PANEL A5226 C0000 00000
ENGINE & ACCY. A5094 20659 00000
FUEL SYSTEM A3022 C0000
COMPARTMENT A2118 A3026 A5240 A6114
WIRING DIAGRAM A5172 A5173 00000
A6363 A6364 00000

Any ideas?
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Skip Douglas SkipD
jmct;8250 wrote:
I am new to this forum, hopefully someone can point me in the right direction. I traded for what I think is a late 1990's SG015, LP fuel, rated 15kw, 120/240 generator. It only has 220 hours on it. I hooked up an LP bottle right after I got it and the engine started immediately, but would surge for a few minutes then die. It would start right back up and do the same. The exhaust smelled a little rich so I figured I wasn't getting enough gas to it thru the little 20lb LP bottle and gas bbq grill regulator I was using. Or I just needed to get a load on it to get smoothed out a little.
Your generator cannot possibly run properly on a 20lb propane cylinder, especially with the small regulator on it. There simply is not enough surface area to convert liquid to gas at the needed rate.

Click on [URL="http://www.mygenerac.com/PublicPDFs/0172610SBY.pdf"][U][COLOR=Blue]this link [/COLOR][/U][/URL] [COLOR=Black]to download Generac's Generator Sizing Guide [/COLOR]and then turn to page 9. You'll need to know the BTU/hour demand for your generator (at full power), the minimum ambient temperature in your area, and then use the top chart on page 9 to choose the minimum size propane tank that will allow the liquid to convert to gas at the consumption rate.

Regarding the voltage output, I have no information on that generator to be able to help there.
Skip Douglas
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jmct
Skip: thanks for confirming what I suspected about the starving the motor for fuel. I've got a 500 gallon LP tank coming which I will set up with a full flow regulator and I will size the line to the generator per the Generac guide (the fuel block solenoid on the generator is 3/4"). SInce I can't find any information either, I will have to take an educated guess on the BTU demand based on similar models?

However, since the engine is turning, shouldn't it try to produce voltage? Or does the voltage regulator hold off on excitation until it sees a steady RPM? It is a 67680 voltage regulator, which I believe was a fairly common unit?
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Skip Douglas SkipD
jmct;8267 wrote:
However, since the engine is turning, shouldn't it try to produce voltage? Or does the voltage regulator hold off on excitation until it sees a steady RPM? It is a 67680 voltage regulator, which I believe was a fairly common unit?
Is there anyone on the forum who can help with this one? I don't have any access to manuals for this model.
Skip Douglas
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mastr
jmct;8267 wrote:
Skip: thanks for confirming what I suspected about the starving the motor for fuel. I've got a 500 gallon LP tank coming which I will set up with a full flow regulator and I will size the line to the generator per the Generac guide (the fuel block solenoid on the generator is 3/4"). SInce I can't find any information either, I will have to take an educated guess on the BTU demand based on similar models??


A typical 15kw gaseous fueled set (of any brand) will consume around 250,000 BTU/Hr at full load.


jmct;8267 wrote:
However, since the engine is turning, shouldn't it try to produce voltage? Or does the voltage regulator hold off on excitation until it sees a steady RPM? It is a 67680 voltage regulator, which I believe was a fairly common unit


It will be difficult to diagnose your trouble until you can get the engine to run smoothly at rated speed. Do that first-once you do, your issue may go away.

There are three LEDs on that VR, the one farthest from the voltage adjust pot is "excitation". If it isn't on, you won't get more than residual voltage. The set probably has a "field boost" or some similar circuit to provide excitation on start up, that has to work. The voltage regulator can't work until it has excitation and at least some small voltage to regulate.

(keep in mind it has been a number of years since I have even seen a set of that vintage) Never had a manual for same, and memory may not be completely reliable.
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ohmslaw
As Mastr stated, start with the field boost circuit and go from there. Regardless of the surging voltage should be present.You also will see voltage produced during the crank cycle on a properly working unit.
Tim
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jmct
First I really appreciate the information you guys are giving me. I like the suggestion of finishing a proper fuel supply before going further. However, I guess one question to ask at this point is, is it worth it? Visually this engine is in great shape, and the rotor/stator section looks great as well.

Does anybody have any experience retrofitting a decent stator/rotor with new controls, i.e. replace the boost, excitation and maybe voltage regulator with something more modern?

In the meantime, it will probably be a few weeks before I get the fuel system in place.

I'm not sure where to start looking for the boost circuit. Would it be a dedicated board?
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mastr
jmct;8272 wrote:
First I really appreciate the information you guys are giving me. I like the suggestion of finishing a proper fuel supply before going further. However, I guess one question to ask at this point is, is it worth it? Visually this engine is in great shape, and the rotor/stator section looks great as well.

Does anybody have any experience retrofitting a decent stator/rotor with new controls, i.e. replace the boost, excitation and maybe voltage regulator with something more modern?

In the meantime, it will probably be a few weeks before I get the fuel system in place.

I'm not sure where to start looking for the boost circuit. Would it be a dedicated board?


If the engine runs good and the all generator windings are OK, it is "probably" worth fixing. The Generac brand VR is readily available if you find it bad. Even if your excitation (DPE) winding is open, there are aftermarket generic replacement VRs available (about $200) that do not need a separate excitation winding.

There are generic replacement engine controllers available, but there is no reason at this point to think there is a serious issue there. The engine troubles you report appear fuel related.

(going from memory here, so anyone with more accurate info feel free to jump in)

The "field boost" applies voltage from the engine control board to the "+" brush lead (usually via a resistor), so look for its lead tied to/under the same lug as the + lead from the VR. Often just another wire with a series resistor and maybe a diode tied to the VR + terminal. Field boost is Generac's term for auto-flashing.
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jmct
Is there any way to post photographs on this forum? I have photos of everything, and it may help in identifying the pieces and parts of this antique.

I will try tracing the boost circuit today. Fuel is still a few weeks off.

While I am in the process of ressurecting old generators, does anybody know of a good supplier of generic 3600 rpm generator sections 6kw? The 13hp motor w elec start on that harbor freight unit is just fine, if I could find a generator section to directly couple to it for around $200 it would be worth it. I think the windings are fine also, if I could find a replacement cast housing for the rear end that cracked.
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Skip Douglas SkipD
jmct;8277 wrote:
Is there any way to post photographs on this forum?
There are two ways to show photographs in the forum. The first, and most recommended, is to link to a photograph. If you have a service where you can store photos on the web then use the following link format:

[/URL]

My example looks a little funny with the underscore, etc., because I tried to display code that is normally hidden in a post.

We can also attach photos to posts, but this requires using server space on Ziller's server to do it.

To get to the photo attachment tools, you have to click on the "Go Advanced" button under the standard "Quick Reply" message box. Then, click on the paperclip icon at the top of the message box. Work your way through the downloading of photos to the server. Then you need to use the paperclip icon again to paste the attachment into your message.

[B]Please edit all photographs so that the width is less than 800 pixels and compress them as much as possible to minimize the storage space required.[/B]
Skip Douglas
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jmct
I finally got some photos posted:

[url]http://www.flickr.com/photos/59289448@N05/[/url]

I have figured out that the 99944-A is the electronic governor. The 67680 is obviously the voltage regulator. Without a wiring diagram the rest is a mystery.
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bronco
I have 13 pages of parts and wiring drawings I can email you. the program I use won't let me email so I have to print and scan them. If you want just get me your email and i will send them.
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jmct
bronco;8445 wrote:
I have 13 pages of parts and wiring drawings I can email you. the program I use won't let me email so I have to print and scan them. If you want just get me your email and i will send them.


Bronco,
Email is jim underscore mct at yahoo dot com
Thanks!
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jmct
I need to apologize to everybody: I whined about not having a manual, and it was under my nose all the time. Another thread led me to pull the ATS cabinet that came with my genset out of the scrap pile, and there in the door, kind of water-stuck to the ATS Manual was the manual for the Genset.

It is mostly identical to drawings Bronco emailed me, but I scanned it anyway and if anyone is interested in a copy, let me know.

So now I am armed to do some troubleshooting and figure out what is broke. Hopefully something small and easy to replace...
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Jack Hottel
jmct,
I would like a copy please.
email is ejhottel at aol dot com
Thanks,
Jack Hottel
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hoghead
I would like a copy
part2 at gmail dot com
Thanks
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Skip Douglas SkipD
jmct;8454 wrote:
Bronco,
Email is jim underscore mct at yahoo dot com
Thanks!


Jack Hottel;8497 wrote:
jmct,
I would like a copy please.
email is ejhottel at aol dot com
Thanks,
Jack Hottel


hoghead;8498 wrote:
I would like a copy
part2 at gmail dot com
Thanks

Fellas, putting your email addresses into posts is a great way to suck a lot of spam.

I edited your email addresses in those three messages so that the automated forum "bots" will have a minimum chance to pick up your email addresses.
Skip Douglas
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jmct
Thanks to Skip for saving us from spam! However, I got a rejection back from hoghead's email, so if he wants to email me I will get him the drawings.

SG015 update: running and producing voltage! Using Bronco's drawings and some troubleshooting from another manual, I isolated the number 4 wire (+ boost to the rotor brush) and jumped in 12VDC of excitation. At first I didn't see the expected VAC at the breaker, but suddenly it was there! Must have been dirty brushes or something like that.

I put the 4 wire back on and removed my jumper. It got exciting for a few seconds because the meter phase selector switch had gotten cocked half way between two phases, producing some sparks, but after I clicked the switch into position all was good.

Now I have to get a load on it and see what it will do. One thing to note is that I am still on the 20lb LP bottle. The initial surging was due to no excitation = absolutely no load on the engine. As soon as I provided excitation to the rotor, this engine smoothed out beautifully. The bigger LP tank is still on the way, but it is nice to know what you can test with.

I will let you know how it does under load. Thanks to everyone for all the help!
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ohmslaw
JMCT,
Check the voltage on the number 4 wire while the unit is cranking. You should have Dc voltage present. If you do not then the field flash circuit is not working properly. This will cause intermittent power production.
Tim
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hoghead
patrt2-gmail
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coreyb38
find wire 0 and wire 4 on vr remove and apply 12v 0=neg 4=brushes check your meter if voltage starts to rise it is definitely worth the trouble there should also be ac voltage present on the other wires on vr but i cant remember the numbers there is a manuals section on the site it will help alot since this set up is common with smaller units
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