| Onan Problems [message #250749] |
Tue, 27 May 2014 15:41  |
bpimm
Messages: 211
Registered: June 2013
Location: Washougal Washington
Karma: 2
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Senior Member |
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I started working on my Onan 4K. Last year I figured out the control board was bad so I swapped in a Dino board last week only to find that the fuel pump was dead as well, it worked last year... I put in the Mr. Gasket pump and to make room for it I deleted the onan voltage regulator. I read somewhere that they caused problems and the Onan start battery will be on a combiner anyway so I pulled it off. Everything was working fine for about 2 hours running the AC as a test then it shut off and won't restart. The latching relay isn't kicking in and keeping the ignition on. The positive side of the coil is only hot when the start switch is closed, as soon as it is released the power drops as well. After more reading I found this comment in the manual. "When the starting rpm increases, the alternator develops a voltage great enough to be rectified and energizes relay K2. Relay K2 contacts close to hold relay K3 energized".
Question: if the voltage regulator/alternator is out of the picture what energizes relay K3 to keep the ignition on?
Also I found Duane Simmons picture of how to remove the regulator and it mentions a double plug that is removed from the regulator but the 2 wires need to remain connected. Mine didn't have a double plug with 2 wires, it had a wire from the alternator labeled AC and one single wire to the control board.
Any advise would be appreciated.
Brian & RaeDean
1973 26' #383
Washougal WA
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| Re: Onan Problems [message #250755 is a reply to message #250749] |
Tue, 27 May 2014 16:27  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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You have it correct. There alternator behind the flywheel puts out around 30 Volts AC. The 30 vac is fed to the board between pins 5 and 8 and tells the board that the Onan is running and to keep the electric fuel pump and ignition going. You can do this by jumpering pins 5 to 9 temporarily to keep it running while checking for 30 VAC at pins 5 to 8.
BTW. How is the oil level? Low oil level will produce the same symptoms. Jumpering pins 5 to 9 bypasses the oil pressure monitoring switch. Make sure the Onan is full of oil before running the Onan with the 5 to 9 jumper installed.
That same 30 VAC also fed the regulator that you removed to charge the Onan battery. You need to figure out if there is 30 VAC vac at pins 5 and 8 with it running. I suspect it is missing.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Onan Problems [message #250788 is a reply to message #250755] |
Tue, 27 May 2014 21:21 |
bpimm
Messages: 211
Registered: June 2013
Location: Washougal Washington
Karma: 2
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Senior Member |
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Ken Burton wrote on Tue, 27 May 2014 14:27You have it correct. There alternator behind the flywheel puts out around 30 Volts AC. The 30 vac is fed to the board between pins 5 and 8 and tells the board that the Onan is running and to keep the electric fuel pump and ignition going. You can do this by jumpering pins 5 to 9 temporarily to keep it running while checking for 30 VAC at pins 5 to 8.
BTW. How is the oil level? Low oil level will produce the same symptoms. Jumpering pins 5 to 9 bypasses the oil pressure monitoring switch. Make sure the Onan is full of oil before running the Onan with the 5 to 9 jumper installed.
That same 30 VAC also fed the regulator that you removed to charge the Onan battery. You need to figure out if there is 30 VAC vac at pins 5 and 8 with it running. I suspect it is missing.
The oil system is working correctly, and there is 40 VAC on terminal 8 from the alternator.
Thanks to ERF for the link to the good schematics.
I haven't got it figured out yet but I have about 1 volt DC on the coil of K2, so not enough to energize it. I did find one wire in the wrong place, the wire to terminal 9 was on 6 instead, When I transferred the wires from the Onan board to the Dino board I marked each one as I transferred it, there are no guarantees that the Onan board was hooked up right or I could have miss marked one.
When I pulled the Dino board back out I found it's equivalent of R1 burned up, the Run circuit looks to be the same as the Onan board, I replaced R1 and it burned up again so I replaced it with a higher value to see what was happening, something is draining the cap and is drawing to much current through the resistor. CR1 looks good measuring it in the board. Tomorrow hopefully I can find my desoldering gear and I'll pull the relay to measure the coil out of the board as well as the cap. from what I can tell there is nothing else in the circuit.
Brian & RaeDean
1973 26' #383
Washougal WA
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| Re: [GMCnet] Onan Problems [message #250792 is a reply to message #250788] |
Tue, 27 May 2014 22:17 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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you should call dino
they warranty the boards and can help you did what is wrong
On Tue, May 27, 2014 at 7:21 PM, Brian Pimm wrote:
> Ken Burton wrote on Tue, 27 May 2014 14:27
>> You have it correct. There alternator behind the flywheel puts out
> around 30 Volts AC. The 30 vac is fed to the board between pins 5 and 8
> and
>> tells the board that the Onan is running and to keep the electric fuel
> pump and ignition going. You can do this by jumpering pins 5 to 9
>> temporarily to keep it running while checking for 30 VAC at pins 5 to 8.
>>
>> BTW. How is the oil level? Low oil level will produce the same
> symptoms. Jumpering pins 5 to 9 bypasses the oil pressure monitoring
> switch.
>> Make sure the Onan is full of oil before running the Onan with the 5 to
> 9 jumper installed.
>>
>> That same 30 VAC also fed the regulator that you removed to charge the
> Onan battery. You need to figure out if there is 30 VAC vac at pins 5 and
>> 8 with it running. I suspect it is missing.
>
>
> The oil system is working correctly, and there is 40 VAC on terminal 8
> from the alternator.
>
> Thanks to ERF for the link to the good schematics.
>
> I haven't got it figured out yet but I have about 1 volt DC on the coil of
> K2, so not enough to energize it. I did find one wire in the wrong place,
> the wire to terminal 9 was on 6 instead, When I transferred the wires from
> the Onan board to the Dino board I marked each one as I transferred it,
> there are no guarantees that the Onan board was hooked up right or I could
> have miss marked one.
>
> When I pulled the Dino board back out I found it's equivalent of R1 burned
> up, the Run circuit looks to be the same as the Onan board, I replaced R1
> and it burned up again so I replaced it with a higher value to see what
> was happening, something is draining the cap and is drawing to much current
> through the resistor. CR1 looks good measuring it in the board. Tomorrow
> hopefully I can find my desoldering gear and I'll pull the relay to measure
> the coil out of the board as well as the cap. from what I can tell there
> is nothing else in the circuit.
>
> --
> Brian & RaeDean
>
> 1973 26' #383
>
> Washougal WA
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
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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| Re: [GMCnet] Onan Problems [message #250833 is a reply to message #250824] |
Wed, 28 May 2014 16:07 |
bpimm
Messages: 211
Registered: June 2013
Location: Washougal Washington
Karma: 2
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Senior Member |
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It sounds like the same problem I'm having, I haven't had the time to do anything with it today. I will have to ask Dino if the fix is just bigger resistors to handle the power being dissipated, where is that current going, I measured over 2 amps through the resistor yesterday and the relay only draws 44mA, where is the rest going? This circuit if floating on top of the 12V supply so maybe somehow it's messing with the 12V supply and feeding back into that.
I'll get back into this soon, I would have drowned outside today if I tried to work on it.
Brian & RaeDean
1973 26' #383
Washougal WA
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| Re: [GMCnet] Onan Problems [message #250844 is a reply to message #250833] |
Wed, 28 May 2014 18:20 |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
Karma: 0
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Senior Member |
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I got a Dino board from JimK a several months ago. Works like a charm.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Onan Problems [message #251006 is a reply to message #250749] |
Fri, 30 May 2014 09:13 |
bpimm
Messages: 211
Registered: June 2013
Location: Washougal Washington
Karma: 2
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Senior Member |
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I got the Dino board from JimK also, it ran for about 2.5 hours then burned up the resistor. I will get in touch with Dino and see if they will mod it like the others, but time is to short to deal with it right now. Here is what I tested yesterday and will finalize today for a short term fix unless someone finds a safety problem with it.
The only thing I can see it doesn't do that the original board did is to monitor the output of the flywheel alternator and that is not being used for anything in my application.
It uses a ignition switch with a start button instead of a single start button. Turn the ignition switch off and it stops or if the oil pressure drops it stops.
Is there anything else the original control board did that I'm overlooking?
Brian & RaeDean
1973 26' #383
Washougal WA
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