| Why do I have a diode between 2 and 10 [message #133169] |
Sun, 03 July 2011 06:17  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Well, I finally found the source of my Onan board problems. Someone in the past added a diode between Onan board pins 2 and 10. Two blown foil patterns and one relay coil later I found the diode and it was shorted.
Has there ever been a suggestion somewhere for this modification? This diode was plugged directly on the board pins. It definitely is not on any Onan wiring diagram I have ever seen. It looks like someone wanted to take starter coil voltage and apply it directly to the ignition coil during cranking.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Why do I have a diode between 2 and 10 [message #133172 is a reply to message #133169] |
Sun, 03 July 2011 08:37  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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2-10??? Makes no sense at all to me. With the anode at 2 it would be
a direct short to ground through the Start switch when closed. With
the anode at 10, it should never pass any current -- unless shorted,
like yours.
As far as added diodes, I did put one across K1 in 2001, as documented
on my version of the Onan schematic. That is, in effect, 7-11. You
reckon someone was trying to duplicate that? Naah -- you had the
coach then.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Sun, Jul 3, 2011 at 7:17 AM, Ken Burton wrote:
>
>
> Well, I finally found the source of my Onan board problems. Someone in the past added a diode between Onan board pins 2 and 10. Two blown foil patterns and one relay coil later I found the diode and it was shorted.
>
> Has there ever been a suggestion somewhere for this modification? This diode was plugged directly on the board pins. It definitely is not on any Onan wiring diagram I have ever seen. It looks like someone wanted to take starter coil voltage and apply it directly to the ignition coil during cranking.
> --
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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] Why do I have a diode between 2 and 10 [message #133182 is a reply to message #133173] |
Sun, 03 July 2011 11:46 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Let me look at those pin numbers again. It was very late when I typed that message. This thing was buried along the board from the top (pin 2) to the bottom under all of the other wiring. It was attached to directly to the pins and covered with shrink tubing. After looking at the wiring diagram for a while it looked like someone was trying to get the +12 going to starter relay (K1) to also go to the ignition and fuel pump while cranking. Once the starter dropped out the diode would in the reverse direction so and the ignition and fuel pump would get it power in the normal circuit through K3. One of the other things I found was the resistor in series with K2 had changed value higher going higher probably delaying the pick of that relay. K2 had slightly less than 8 volts on it. I fixed that. I'm thinking this was someones fix to keep the ignition going while waiting for k2 to pick up.
It sure drove me nuts trying to figure it all out. At less than $150 aftermarket boards are looking better all the time. I can swap one in less than 10 minutes.
Oh well, it is running now. I seldom use the generator anyway. I use it once and a while for the microwave or for a tank of hot water in the morning when I dry camp. I did use it once for additional AC while driving when the outside temp was around 100 degrees.
I'll go back to chasing an APRS radio problem today that I've been trying to find for almost two weeks. I can do that inside. It was 98 all day here yesterday with the humidity at the same number. I was actually driving in the rain yesterday with the OAT at 98. It kind of sounds like Georgia summer weather. We had 4.5 inches of rain the day before.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Why do I have a diode between 2 and 10 [message #133199 is a reply to message #133169] |
Sun, 03 July 2011 13:17 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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It it's across the relay coil, it is probably for flyback suppression when the coil denergizes...
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] Why do I have a diode between 2 and 10 [message #133232 is a reply to message #133212] |
Sun, 03 July 2011 20:07 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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It's gonna have to raise the Gulf of Mexico enough to back the
Apalachicola River up enough to reverse-overflow a couple of dams
'fore it'll reach us that way. :-)
Ken H.
On Sun, Jul 3, 2011 at 5:47 PM, Ken Burton wrote:
>> Ken Henderson wrote on Sun, 03 July 2011 12:04
>> Quit hogging all the H2O. We got <0.10".
> We will send it back down the Mississippi river to you.
> --
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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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