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  #1  
Old 04-22-2019, 11:07 AM
WingnutWick's Avatar
WingnutWick WingnutWick is offline
 
Join Date: Jun 2013
Location: Lemoore
Posts: 187
Default Questions on ignition switch - push button

Hello,

I am changing an RV-6A over to push button starting which I did with my 8 with success and I love it. Looking at this 6's switch on the back there are a couple things I am not sure what they are for however. First is a jumper that looks like it has a diode in it connecting the + to the ground. What is this for? Is it needed? At the moment I just took the + and the starter and connected them to the push start button.

Finally, in the photo, off the mag wire there are two other white wires coming out. They aren't labeled and I can't get a good trace on where they go without completely undoing everything. Any ideas what these could be?

This is an H2AD O-320 with one of those dual siamese - type mags. Only one side is being used as it has an electronic ignition as well.

Thank you for the help!

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  #2  
Old 04-22-2019, 11:16 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
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Default

A diode connected in parallel with a start contactor coil will short out induced voltage spikes, thus protecting switch contacts from arcing and sparking.
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  #3  
Old 04-22-2019, 11:50 AM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Default

Quote:
Originally Posted by Mich48041 View Post
A diode connected in parallel with a start contactor coil will short out induced voltage spikes, thus protecting switch contacts from arcing and sparking.
+1

Definately want a diode to snub the collapsing coil current. However, it can just as easily be installed at the solenoid instead of the switch.

White wires are probably P leads grounds. Best practice for p leads is a 16 or 18 ga shielded wire. Core comes from p lead post on mag and shield goes to mag ground screw. Ignition switch closes the core and shield to kill the ignition.

Larry
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Last edited by lr172 : 04-22-2019 at 11:54 AM.
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  #4  
Old 04-22-2019, 12:10 PM
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WingnutWick WingnutWick is offline
 
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Location: Lemoore
Posts: 187
Default Follow up

Thank you,

So can I just take that diode and install it on the Push to Start switch somehow? If so, how? Or if on the solenoid (which may be easiest) I simply run it from the “s” terminal to one off the firewall mounting bolts from what I gather looking online.

As for the two white wires, my understanding was that when you turn the key off, it connects the P-lead to the ground section of the switch - grounding and thus disabling the mag. So why need grounding wires if the P-lead is being grounded? Again, to test my understanding - I have hooked all those three wires (P-lead and two white wires) to one side of a toggle ignition switch, and the previous ground wire from the key switch to the other contact on the new toggle switch. This should operate the same way as the key, even if I’m not sure what the two wires are for?

Thanks for the help!


Quote:
Originally Posted by lr172 View Post
+1

Definately want a diode to snub the collapsing coil current. However, it can just as easily be installed at the solenoid instead of the switch.

White wires are probably P leads grounds. Best practice for p leads is a 16 or 18 ga shielded wire. Core comes from p lead post on mag and shield goes to mag ground screw. Ignition switch closes the core and shield to kill the ignition.

Larry
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Rhino driver by trade
RV-8 O-360

Last edited by WingnutWick : 04-22-2019 at 01:53 PM.
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  #5  
Old 04-22-2019, 03:41 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,298
Default

Quote:
Originally Posted by WingnutWick View Post
Thank you,

So can I just take that diode and install it on the Push to Start switch somehow? If so, how? Or if on the solenoid (which may be easiest) I simply run it from the “s” terminal to one off the firewall mounting bolts from what I gather looking online.

As for the two white wires, my understanding was that when you turn the key off, it connects the P-lead to the ground section of the switch - grounding and thus disabling the mag. So why need grounding wires if the P-lead is being grounded? Again, to test my understanding - I have hooked all those three wires (P-lead and two white wires) to one side of a toggle ignition switch, and the previous ground wire from the key switch to the other contact on the new toggle switch. This should operate the same way as the key, even if I’m not sure what the two wires are for?

Thanks for the help!
Yes, diode from S term to ground with the diode's band closest to the S term side. If installed at the switch, it must be on the switched lead/terminal NOT the source. P lead should be grounded at the mag to avoid noise issues. In theory, it can go to any ground that is shared with the engine. However, to avoid noise it should be grounded at the mag. P lead can generate noise, as it is attached to the coil's secondary winding and the shield grounded at the mag helps to capture the magnetic energy generated on the core wire and return it to the mag. Don't recommend that you deviate from that.

I have never wired an ignition switch, so don't really know what those two white wires are other than the p lead grounds. I believe it should have start power in, start power out, L ign, L ign grd, R ign, R ign grd. that is what it would have if I built it.

Larry
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N11LR - RV-10, Flying as of 12/2019

Last edited by lr172 : 04-22-2019 at 03:49 PM.
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  #6  
Old 04-22-2019, 09:19 PM
DMFenster DMFenster is offline
 
Join Date: Jan 2012
Location: Woodbridge, VA
Posts: 90
Default Tach

Tach wires??? Maybe
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  #7  
Old 04-24-2019, 06:55 PM
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WingnutWick WingnutWick is offline
 
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Default I think I have it

I think this?ll do the trick???

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  #8  
Old 04-24-2019, 08:24 PM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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Default

Yes, as long as the diode polarity is correctly marked with that red band.
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