Wiring up dual P-Mags?

N941WR · #1 12-01-2006, 06:29 AM

I was following Bob's figure Z-33 (Rev -K- 04/20/05) to wire my P-mags and realized there may be some issues with the diagram.

The first being that EmagAir now recommends using 18 AWG wire for the power and ground leads. The second being that Bob references wire colors for the Pmag which are not there on the new mags.

Could someone who has exeperiance with these things take a look at the attached drawing and let me know if my diagram is correct?

[edit 6/17/07] The diagram posted here has been superseded, see post #8 below. [End of edit]

Thanks for the help!

Davepar · #2 12-01-2006, 09:34 AM

That's how I wired mine, except I didn't include a hand-prop switch. I don't expect to ever hand prop the plane.

Davepar · #3 12-01-2006, 10:03 AM

I should mention one other thing. I thought I needed that "hand prop" switch for set up. That's true if you're setting the timing via the LED or by blowing in the manifold pressure sensor. If you're using EICAD, the P-mag needs to be fully on and enabled, so the hand prop switch isn't needed. However, it seems that the EICAD software isn't yet able to set the timing, although that feature is mentioned on the web site.

Hooking up the 3 wires for the EICAD interface is a good idea. I have them wired to a connector behind the subpanel. You'll be able to monitor manifold pressure, advance angle, RPM, etc. via that interface (and a laptop). Might be handy for debugging later.

N941WR · #4 12-01-2006, 11:22 AM

Dave,

Thanks for the reply.

I plan on wiring in the EICAD and need to add that to the drawing but wanted to keep it simple for those who might offer a comment.

As for the ground service switch, I replaced that (and the light) with a 1/8" mono jack and plug, complete with "remove before flight" flag. That way there is no chance of it being turned on in flight.

I'll finish the wiring tonight or this weekend.

frankh · #5 06-13-2007, 12:33 PM

Hey guys,

I couldn't find anywhere in the documentation what terminals to wire the TX and RX connections on the P mag (connections #2 and #3 respectively) ...I.e where on the serial plug that goes into the laptop do i wire the above terminals?

With AVgas a 4.25 I'm starting to think mogas again but with the max advance limited to 25 BTDC...hence I need Eicad.

Thanks

frank

scard · #6 06-13-2007, 02:23 PM

launch the eicad app on the laptop. It has a wiring diagram in there.

penguin · #7 06-13-2007, 04:02 PM

I can't download a good copy of your diagram, but you do need to be able to power up the P-mag with the ignition off to set the timing. I think that is one reason for a hand-prop switch?

Pete

N941WR · #8 06-16-2007, 10:57 PM

Gang,

I just noticed this thread came back to life.

Today I finally got around to timing my engine and ran into one small issue. You can't use a mono plug to put it in ground service mode as that will short it to ground, poping a breaker.

The solution is to use a stereo jack and plug.

Anyway, here is the updated drawing:

The answer to Pete's question is simple. Put the shorted plug into the jack, leave the P-mag switchs off, and turn on the master. The plug works as a switch, putting both mags into ground service mode so they can be timed.