Home » Public Forums » GMCnet » Rewinding Onan Ignition-side Stator
| Rewinding Onan Ignition-side Stator [message #337668] |
Sun, 07 October 2018 09:27  |
jcurran
Messages: 52
Registered: May 2009
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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
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| Re: Rewinding Onan Ignition-side Stator [message #337670 is a reply to message #337668] |
Sun, 07 October 2018 11:54  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
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jcurran wrote on Sun, 07 October 2018 10:27Due 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 - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Rewinding Onan Ignition-side Stator [message #337672 is a reply to message #337670] |
Sun, 07 October 2018 12:28 |
Jim Miller
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Registered: March 2008
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On Oct 7, 2018, at 12:54 PM, Matt Colie wrote:
> 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
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Rewinding Onan Ignition-side Stator [message #337674 is a reply to message #337672] |
Sun, 07 October 2018 12:41 |
Dolph Santorine
Messages: 1236
Registered: April 2011
Location: Wheeling, WV
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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
> On Oct 7, 2018, at 1:28 PM, Jim Miller wrote:
>
>> On Oct 7, 2018, at 12:54 PM, Matt Colie wrote:
>>
>> 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
>
>
>
>
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| Re: [GMCnet] Rewinding Onan Ignition-side Stator [message #337681 is a reply to message #337680] |
Sun, 07 October 2018 19:44 |
Jim Miller
Messages: 501
Registered: March 2008
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On Oct 7, 2018, at 7:59 PM, John R.Lebetski wrote:
> 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
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Rewinding Onan Ignition-side Stator [message #337682 is a reply to message #337681] |
Sun, 07 October 2018 20:02 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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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 Sun, Oct 7, 2018 at 8:45 PM Jim Miller wrote:
> On Oct 7, 2018, at 7:59 PM, John R.Lebetski
> wrote:
>
>> 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
>
>
>
>
> _______________________________________________
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> Unsubscribe or Change List Options:
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Rewinding Onan Ignition-side Stator [message #337684 is a reply to message #337682] |
Sun, 07 October 2018 20:23 |
Jim Miller
Messages: 501
Registered: March 2008
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On Oct 7, 2018, at 9:02 PM, Ken Henderson wrote:
> 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
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Rewinding Onan Ignition-side Stator [message #337685 is a reply to message #337684] |
Sun, 07 October 2018 21:06 |
jcurran
Messages: 52
Registered: May 2009
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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
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| Re: [GMCnet] Rewinding Onan Ignition-side Stator [message #337686 is a reply to message #337685] |
Sun, 07 October 2018 21:41 |
Jim Miller
Messages: 501
Registered: March 2008
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On Oct 7, 2018, at 10:07 PM, Jim Curran wrote:
> 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
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Rewinding Onan Ignition-side Stator [message #337784 is a reply to message #337686] |
Thu, 11 October 2018 09:15 |
Mr ERFisher
Messages: 7117
Registered: August 2005
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I have used the transformer very sucessfully on my propane conversions .
Gene
On Sun, Oct 7, 2018 at 7:42 PM Jim Miller wrote:
> On Oct 7, 2018, at 10:07 PM, Jim Curran wrote:
>
>> 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://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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