Rewinding Onan Ignition-side Stator

[jim curran]

Due to a short circuit, I need to rewind the engine-side stator on my 4K Onan. I have removed it and I guess I could shoot video of unwinding it but
thought I'd ask the Forum how it is done.

Thanks,
Jim
--
Jim Curran
1976 Palm Beach
Alexandria, OH

 

[powwerjon]

Get ahold of Jim Bounds and see if he has a used one. As for rewinding yourself, that is probably not a good choice. Jim Miller does a lot of work rewinding the 6K units. Might consider a replacement, not sure what other have used.

JR Wright
Michigan

>
> Due to a short circuit, I need to rewind the engine-side stator on my 4K Onan. I have removed it and I guess I could shoot video of unwinding it but
> thought I'd ask the Forum how it is done.
>
> Thanks,
> Jim
> --
> Jim Curran
> 1976 Palm Beach
> Alexandria, OH
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Matt Colie]

> Due to a short circuit, I need to rewind the engine-side stator on my 4K Onan. I have removed it and I guess I could shoot video of unwinding it
> but thought I'd ask the Forum how it is done.
>
> Thanks,
> Jim

Jim,

While that might be an interesting project, you could just put a door bell transformer on the AC output of the electric end and feed that where the
now dead stator winding used to go. That winding has two purposes, one to supply the start battery recharger, and unless you have an old 23, that is
usless, and the other is the "runnng" signal to the control board.

Matt - still in Albany
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[jim miller]

> While that might be an interesting project, you could just put a door bell transformer on the AC output of the electric end and feed that where the now dead stator winding used to go

I’ve heard this doorbell transformer idea kicked around the past - has anyone tried it?

The reason I ask is this: The control board uses output voltage of the flywheel alternator to drive an RC network on the control board which determines whether the engine has reached self-sustain speed; when that happens the control board latches the ignition system, fuel pump and fuel solenoid and disconnects the control voltage to the starter solenoid. All of this happens even if the start button is held down longer than it needs to be.

The R in this RC network is the one that smokes on some Dinosaur boards and when repairing them I have discovered that this RC network is very finicky. If things in the circuit are not "just right" then in some cases the handover happens before the engine has reached self-sustain and thus it stalls and kicks the starter back in - and in other cases it takes too long to kick in and the starter just keeps running and the fuel/ignition latchup never happens.

If the AC output via the doorbell transformer does not come up at the correct rate compared to the engine RPM then you may see the misbehavior I’ve described above.

—Jim

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[adolph santorine]

Jim

Thanks for the input.

As they say, “you da man” when it comes to the Onan.

Dolph Santorine

DE AD0LF

Wheeling, West Virginia

1977 ex-Palm Beach TZE167V100820
1-ton, Sullybuilt Bags, Reaction Arms, Manny Transmission

>

>>
>> While that might be an interesting project, you could just put a door bell transformer on the AC output of the electric end and feed that where the now dead stator winding used to go
>
> I’ve heard this doorbell transformer idea kicked around the past - has anyone tried it?
>
> The reason I ask is this: The control board uses output voltage of the flywheel alternator to drive an RC network on the control board which determines whether the engine has reached self-sustain speed; when that happens the control board latches the ignition system, fuel pump and fuel solenoid and disconnects the control voltage to the starter solenoid. All of this happens even if the start button is held down longer than it needs to be.
>
> The R in this RC network is the one that smokes on some Dinosaur boards and when repairing them I have discovered that this RC network is very finicky. If things in the circuit are not "just right" then in some cases the handover happens before the engine has reached self-sustain and thus it stalls and kicks the starter back in - and in other cases it takes too long to kick in and the starter just keeps running and the fuel/ignition latchup never happens.
>
> If the AC output via the doorbell transformer does not come up at the correct rate compared to the engine RPM then you may see the misbehavior I’ve described above.
>
> —Jim
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[RF_Burns]

My Onan used to be a bit temperamental in starting. So I added the prime button which primed the carb fast, but it still would die a couple times
before coming up to speed.

So I changed my starting procedure to a two finger start. I press and hold the prime button while listening for the fuel pump to change its sound.
This lets me know the carb is filled with fuel. Then while still holding the prime button, I use a second finger to press the Start button. It then
starts and runs up to operating RPM every time. At that point I release the prime button.

My reasoning for holding the prime button during start-up is it simply provides power directly to the fuel pump / ignition connection. So holding the
prime button keeps constant power to the ignition until the run relay is latched.

This procedure may help those with the RC network timing issue Jim speaks of.

JWID.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

 

[john r. lebetski]

I would think that the main alternator voltage would "come up" in a similar way to the flywheel alternator as RPM increases.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[jim miller]

> I would think that the main alternator voltage would "come up" in a similar way to the flywheel alternator as RPM increases.

Hi John,

That may very well be the case! I have not measured it, however, nor have I heard of any success or failure stories with the doorbell transformer technique so I can’t be sure.

Mr. Faraday tells us that E (voltage) is proportional to the rate of change of magnetic flux with respect to time. There are only 4 poles in the main alternator but there are many more in the flywheel stator - plus more magnets too IIRC - so it would seem to me that the two voltages would come up at different rates. I currently have an Onan on the workbench for ignition R&D so I’ll have to rig up an experiment and see what is really happening. I may even have a doorbell transformer around to experiment with!

—Jim

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[Ken H.]

Jim,

My 4kW Onan came with a badly deteriorated flywheel alternator stator. I
took it to a rewinder and they basically dipped it in varnish and baked it
dry before returning it to me as "refurbished". It worked for a couple of
years before it failed. Being 12+ years ago, I don't remember whether it
shorted or opened, but that's immaterial: I DID go the bell transformer
route and had no trouble with starting. I did, however, have long-time
running problems which might have been related to heating of that
transformer, or 'most any other component, including the Pertronix. I
finally I gave up on that generator and installed an even more troublesome
Generac 36G (now replaced with a very reliable and noisy TroyBilt). I
should note that my son still uses the 4kW, mounted on a trailer, as his
home's emergency power source -- with no reported problems.

Good luck with your experiments.

Ken H

> On Oct 7, 2018, at 7:59 PM, John R.Lebetski

>
> > I would think that the main alternator voltage would "come up" in a
> similar way to the flywheel alternator as RPM increases.
>
> Hi John,
>
> That may very well be the case! I have not measured it, however, nor have
> I heard of any success or failure stories with the doorbell transformer
> technique so I can’t be sure.
>
> Mr. Faraday tells us that E (voltage) is proportional to the rate of
> change of magnetic flux with respect to time. There are only 4 poles in the
> main alternator but there are many more in the flywheel stator - plus more
> magnets too IIRC - so it would seem to me that the two voltages would come
> up at different rates. I currently have an Onan on the workbench for
> ignition R&D so I’ll have to rig up an experiment and see what is really
> happening. I may even have a doorbell transformer around to experiment with!
>
> —Jim
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[jim miller]

> I DID go the bell transformer route and had no trouble with starting.
> […]

Thank you for sharing that Ken, that is a good data point!

…and thank you for sharing the story about your interaction with Pertronix engineering re the 1181 and its eternal dwell time - that gives me more confidence in my observations and analysis.

—Jim

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[jim curran]

Guys,

For what its worth, I did try the transformer idea. I plugged a 24 vdc wall wart into the house electric and ran the output DC (I know it ought to be
27vdc) back to the control board and it mostly worked. I was dealing with some control board problems while I was testing this out but I came a way
generally satisfied that if the control board was working correctly, the transformer idea would work. But I wanted to pull the flywheel and see where
the oil leaks are and also try to keep the generator "stock" for the next owner.

I tried finding an automotive electric shop that would rewind and even found a shop that lived and breathed generator and motor repair but they said
that they couldn't do it. I guess I will figure out what gauge wire was used and order a roll. Nothing to lose.

Jim
--
Jim Curran
1976 Palm Beach
Alexandria, OH

 

[jim miller]

> I tried finding an automotive electric shop that would rewind and even found a shop that lived and breathed generator and motor repair but they said that they couldn't do it. I guess I will figure out what gauge wire was used and order a roll. Nothing to lose.

I see no reason why you could not pull this off Jim. Match the wire gauge as well as the turns count and direction of wind on each pole piece and you should be good. It would be helpful if you had a known good specimen to compare resistances and other parameters compared to your re-wound assembly but in the absence of a known good specimen just match the original’s setup and see what happens.

The finishing touch is to dip the final product in motor varnish and bake it. I don’t have a varnish tank nor an oven big enough for baking so I went a different route with my Onan field re-winds - I use a commercial insulating epoxy and immerse each coil into it for a sufficient amount of time to let the epoxy displace all the air in the coil. I use Dolph’s AC-46 (about $150/gallon) although you could also use the classic Glyptal as well - either one will encapsulate the windings and keep them from moving relative to one another which is a very important aspect of reliability.

—Jim


Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[Gene Fisher]

I have used the transformer very sucessfully on my propane conversions .
Gene

>
> > I tried finding an automotive electric shop that would rewind and even
> found a shop that lived and breathed generator and motor repair but they
> said that they couldn't do it. I guess I will figure out what gauge wire
> was used and order a roll. Nothing to lose.
>
> I see no reason why you could not pull this off Jim. Match the wire gauge
> as well as the turns count and direction of wind on each pole piece and you
> should be good. It would be helpful if you had a known good specimen to
> compare resistances and other parameters compared to your re-wound assembly
> but in the absence of a known good specimen just match the original’s setup
> and see what happens.
>
> The finishing touch is to dip the final product in motor varnish and bake
> it. I don’t have a varnish tank nor an oven big enough for baking so I went
> a different route with my Onan field re-winds - I use a commercial
> insulating epoxy and immerse each coil into it for a sufficient amount of
> time to let the epoxy displace all the air in the coil. I use Dolph’s AC-46
> (about $150/gallon) although you could also use the classic Glyptal as well
> - either one will encapsulate the windings and keep them from moving
> relative to one another which is a very important aspect of reliability.
>
> —Jim
>
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html