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[GMCnet] Never assume anything [message #269694] Wed, 14 January 2015 19:02 Go to next message
glwgmc is currently offline  glwgmc   United States
Messages: 1014
Registered: June 2004
Karma: 10
Senior Member
The Onan in the Royale that we have owned for more than a dozen years always started (sometimes a bit reluctantly) and ran ok so when I decided to install one of Gary Bovee's Pertronix kits I never even thought about starting the Onan first. I just pulled the covers off the front, located the timing mark, filed one cooling fin to accept the magnet, installed the module and got to the part about connecting the red module wire to the + terminal on the coil and the black module wire to the - terminal on the coil. Hmmmm. The coil appeared to be installed backward. The 12 vdc wire, the condenser and the other power wires all connected to the terminal marked -. Only the wire from the points connected to the + terminal. It must have been running this way the whole time we have owned the coach as I have never touched anything to do with the coil.

No matter which module wire went to + and which went to - the Onan would turn over well but not start. I checked and found the 5 amp fuse blown. Hmmmm again, as that had never been replaced either. With a good fuse the Onan would start and run on the points, but not on the module and I then found the fuse blown yet again. In replacing it for the second time I found the upper fuse holder loose. Off came the board and I resoldered that connection plus cleaned the board and all the terminals. Still would not run.

A couple of calls to Gary left him about as confused as I was. He was nice enough to check his Onan coil wiring and sure enough all the right stuff was on the + terminal and only the black wire from the module was on the -. So, I tore the board and board support off to loosen the coil clamp, rotated it 180 degrees and buttoned everything back up. Still would not start even though it turned over really well. I jumpered 5-9 and it would start and run on either the points or the module and the fuse did not blow. My speculation is one of the relays is faulty so I just called JimK to order a new board rather than trying to diagnose further or start trying to find a new relay out here in the boonies. In fairness, that board is 40 years old so I guess it is time for it to fail - if that is the root cause issue!

What really has me curious is why the Onan started and ran for all these years off the points with the coil polarity reversed, but refused to do so from the module with the polarity reversed. Any of the electrically enabled posters able to explain that one? I will let you know the full outcome when the new board is in.

Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com







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Jerry & Sharon Work
78 Royale
Kerby, OR
Re: [GMCnet] Never assume anything [message #269699 is a reply to message #269694] Wed, 14 January 2015 19:57 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
glwgmc wrote on Wed, 14 January 2015 20:02
The Onan in the Royale that we have owned for more than a dozen years always started (sometimes a bit reluctantly) and ran ok so when I decided to install one of Gary Bovee's Pertronix kits I never even thought about starting the Onan first. I just pulled the covers off the front, located the timing mark, filed one cooling fin to accept the magnet, installed the module and got to the part about connecting the red module wire to the + terminal on the coil and the black module wire to the - terminal on the coil. Hmmmm. The coil appeared to be installed backward. The 12 vdc wire, the condenser and the other power wires all connected to the terminal marked -. Only the wire from the points connected to the + terminal. It must have been running this way the whole time we have owned the coach as I have never touched anything to do with the coil.

No matter which module wire went to + and which went to - the Onan would turn over well but not start. I checked and found the 5 amp fuse blown. Hmmmm again, as that had never been replaced either. With a good fuse the Onan would start and run on the points, but not on the module and I then found the fuse blown yet again. In replacing it for the second time I found the upper fuse holder loose. Off came the board and I resoldered that connection plus cleaned the board and all the terminals. Still would not run.

A couple of calls to Gary left him about as confused as I was. He was nice enough to check his Onan coil wiring and sure enough all the right stuff was on the + terminal and only the black wire from the module was on the -. So, I tore the board and board support off to loosen the coil clamp, rotated it 180 degrees and buttoned everything back up. Still would not start even though it turned over really well. I jumpered 5-9 and it would start and run on either the points or the module and the fuse did not blow. My speculation is one of the relays is faulty so I just called JimK to order a new board rather than trying to diagnose further or start trying to find a new relay out here in the boonies. In fairness, that board is 40 years old so I guess it is time for it to fail - if that is the root cause issue!

What really has me curious is why the Onan started and ran for all these years off the points with the coil polarity reversed, but refused to do so from the module with the polarity reversed. Any of the electrically enabled posters able to explain that one? I will let you know the full outcome when the new board is in.

Jerry

Jerry,

Because on an Onan, coil polarity doesn't matter.
Ego, I believe you have some further trouble shooting to do if the replacement board doesn't do it.

The reason coil polarity ever mattered is because of the fact that spark plugs are sort of polar at higher temperatures.

Matt


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
Re: [GMCnet] Never assume anything [message #269700 is a reply to message #269694] Wed, 14 January 2015 19:59 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Jerry,

I'm not surprised that the Onan ran fine with the + & - terminals reversed
-- I'm not even sure why those markings are on there since the polarity
should not matter in the "lost spark" ignition. But the only explanation I
have for the failure to run is not one you want to hear: Operator error.
Sorry, but one specific Onan-related event tells me it's not beyond the
realm of possibiity:

Years back, when we first began installing Pertronix, I helped Bobby Moore
modify his at Bean Station. While we were doing that, a dear friend, now
deceased, with BSME and MSEE degrees from GA Tech, and many years'
experience in general and GMC's specifically, was doing routine maintenance
on another Onan nearby.

When we finished with Bobby's project, I wandered over to the other crowd
where the primary, smartest guy in the bunch, was getting LOTS of peanut
gallery help. They'd been trying for 30 minutes to get the Onan to run.
Having just come from having the wiring indelibly engraved in my short-term
memory, I glanced at the coil and said, "Move that wire from there to
there.", turned, and walked away. I wasn't 15 feet away when I heard the
engine running.

If it could happen to him, I could happen to ANYONE! :-)

Ken H.


On Wed, Jan 14, 2015 at 8:02 PM, Work Jerry wrote:

> The Onan in the Royale that we have owned for more than a dozen years
> always started (sometimes a bit reluctantly) and ran ok so when I decided
> to install one of Gary Bovee's Pertronix kits I never even thought about
> starting the Onan first. I just pulled the covers off the front, located
> the timing mark, filed one cooling fin to accept the magnet, installed the
> module and got to the part about connecting the red module wire to the +
> terminal on the coil and the black module wire to the - terminal on the
> coil. Hmmmm. The coil appeared to be installed backward. The 12 vdc
> wire, the condenser and the other power wires all connected to the terminal
> marked -. Only the wire from the points connected to the + terminal. It
> must have been running this way the whole time we have owned the coach as I
> have never touched anything to do with the coil.
>
> No matter which module wire went to + and which went to - the Onan would
> turn over well but not start. I checked and found the 5 amp fuse blown.
> Hmmmm again, as that had never been replaced either. With a good fuse the
> Onan would start and run on the points, but not on the module and I then
> found the fuse blown yet again. In replacing it for the second time I
> found the upper fuse holder loose. Off came the board and I resoldered
> that connection plus cleaned the board and all the terminals. Still would
> not run.
>
> A couple of calls to Gary left him about as confused as I was. He was
> nice enough to check his Onan coil wiring and sure enough all the right
> stuff was on the + terminal and only the black wire from the module was on
> the -. So, I tore the board and board support off to loosen the coil
> clamp, rotated it 180 degrees and buttoned everything back up. Still would
> not start even though it turned over really well. I jumpered 5-9 and it
> would start and run on either the points or the module and the fuse did not
> blow. My speculation is one of the relays is faulty so I just called JimK
> to order a new board rather than trying to diagnose further or start trying
> to find a new relay out here in the boonies. In fairness, that board is 40
> years old so I guess it is time for it to fail - if that is the root cause
> issue!
>
> What really has me curious is why the Onan started and ran for all these
> years off the points with the coil polarity reversed, but refused to do so
> from the module with the polarity reversed. Any of the electrically
> enabled posters able to explain that one? I will let you know the full
> outcome when the new board is in.
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] Never assume anything [message #269764 is a reply to message #269694] Thu, 15 January 2015 20:15 Go to previous messageGo to next message
jhbridges is currently offline  jhbridges   United States
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
Senior Member
Jerry -
If you were gonna toss the old card, how's to send me it? Fits in a small standard USPS Priority Mail Flat Rate box, I'll send you the six bux.

--johnny


Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell
Re: [GMCnet] Never assume anything [message #269791 is a reply to message #269694] Fri, 16 January 2015 15:27 Go to previous message
dwayne jacobson[1] is currently offline  dwayne jacobson[1]   United States
Messages: 345
Registered: July 2009
Karma: 0
Senior Member
Sounds great. Bring the info to our next rally.
Regards
Dwayne




Sent from Samsung tabletWork Jerry wrote:The new board came today.  I installed it, pressed the start switch and the Onan sprang to life.  As soon as it warmed up a minute or so it ran evenly, put out 125vac with no load and 115VAC under load.  So, the combination of the module plus a new board and it sounds better and smoother than it ever has.  Good use of $250 or so.  The new board with the pig tail soldered on looks like a much higher quality piece that the stock board with all those push on connectors ever did.  Thanks to all who offered advice and suggestions.  My suggestion is to make sure the polarity on the coil is correct before hooking up the module!

Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com







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