dual pmag conection to SV EMS.from newest SV owner

rlallen1

I love flying!
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Dec 12, 2011
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Just rec'd my SV yesterday ;D I have been reading the install manual for the last few days, weeks getting ready. My first question...there will be many... I have dual PMags, the pmag instrux say to only connect one tach reading to the EFIS, but the SV EMS pin out gives to places PIN 32 and 33. I was wondering as to how others have connected these, one or both...
 

dynonsupport

Dynon Technical Support
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You can hook up both. Some EFISes can only take one tach signal, which may be the origin of the advice. Also, if the tach signal doesn't go away, even when the pmag isn't providing spark during mag check, then that would be another reason that only one would be strictly necessary except if that singly connected unit failed.

The main reason we have two inputs is that in a conventional mag setup, each mag goes away completely, as far as the EMS can see, when you do your mag check. So having two inputs lets Dynon systems automatically look at the other one to maintain a tach reading.
 

mmarien

Murray M.
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I have dual P-Mags and have both connected. As mentioned above, the signal doesn't go away when you ground it out (mag check) but having both connected allows some redundancy. While you asking, be sure to mention it would be nice to be able to display the firing angle on Skyview.
 

rlallen1

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Dec 12, 2011
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Did you connect the 20 gauge ground wire from the EMS D37 directly to the Pmag Pin1. Reason I ask is the Pmag instructs say to use 18 gauge ground, but the dynon ems is 20 gauge ground...wasn't sure if it mattered or not but wanted to find out before I proceeded.
 

schristo

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Did you connect the 20 gauge ground wire from the EMS D37 directly to the Pmag Pin1.  Reason I ask is the Pmag instructs say to use 18 gauge ground, but the dynon ems is 20 gauge ground...wasn't sure if it mattered or not but wanted to find out before I proceeded.

Pmag calls for the ground to be to a hard case point... I plan to ground on a nearby case stud... no need to carry it back with signal wires since it is not being used for a reference.
 

rlallen1

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the Pmag install manual shows on the electrical diagram 2 grounds coming out of pin1. one ground wire to the engine case and another to the efis. Am I not reading the diagram correctly?
 

schristo

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the Pmag install manual shows on the electrical diagram 2 grounds coming out of pin1.  one ground wire to the engine case and another to the efis.  Am I not reading the diagram correctly?

Gotcha... if you take a second ground to the EIFS for a tach reference it would only need to be 22 gauge similar to the tach signal line. I doubt that the reference ground is actually actually needed since your EFIS is likely getting its ground from a block on the firewall with a direct hard connection to the engine case and battery.
 

mmarien

Murray M.
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I don't have the GND wire to the EFIS and don't have any signal problems with the tach output. This is new since my manual LC114v13. Grounding is the most important connection so if there were problems with the tach signal the extra ground wouldn't hurt.

I did add a serial connection to pins 2 and 3 to connect to a computer running EICAD. They ask for shielded wire and a ground. See here:

http://www.emagair.com/EICADII.htm

This is the connection I was hinting would be nice to have on Skyview rather than having to carry a laptop or purchase the EI Commander.
 

rlallen1

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Dec 12, 2011
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Just to follow up...after email with Brad from emagair..the extra ground from the pin 1 is not needed to go the efis, it only needs the 18g ground going to the engine case.
 
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