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Posted: Thu Jan 01, 2009 10:21 pm Post subject: EI SC-5 clock doc error question |
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Hi Ron. I was finishing the install on the SC-5 tonight. I ran the brown wire in parallel with the oil low pressure light through the NC side of the pressure switch. Just to clarify C what did you end up doing with the orange wire since you said it was superfluous to the engine timer? Just leave it unconnected and tie it off? I appreciate your input C thanks in advance.
Jim B
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Date: Tue C 30 Dec 2008 13:28:13 -0800
From: rshannon(at)CRUZCOM.COM
To: aeroelectric-list(at)matronics.com
Subject: EI SC-5 clock doc error
The previous post inspired me to share this recent discovery.
The EI SC-5 clock includes a non-resettable total engine time counter C essentially a Hobbes function. The manual says that in a 12V system C the ORANGE wire should be connected via an N.O. oil pressure switch to provide +12V on closure C when oil pressure develops C which will start the engine timer. This is a little tricky with the B&P oil presure switch C where the N.O. contact is normally grounded -- I even set up a little relay to power the wire that way -- but don't bother. Contrary to the manual C any time the RED +12V main supply wire is hot C the engine timer runs C regardless of what's is or isn't happening on the ORANGE wire. For example C if you're running the panel on ground power C perhaps for training or maintenance C or just entering a flight plan into the GPS before engine start C the engine timer will be ticking up C even though the engine isn't running. (The clock is supposed to be wired to a main bus or e-bus C so it's going to be ON when most anything on the panel is on.) Incidentally C the manual also says that in a 12V system C the BROWN wire should _not_ be connected to anything.
After considerable consultation with EI C it was confirmed that the ORANGE wire is at best superfluous to the engine timer function (or any function as far as I could determine) and the BROWN wire is what must be used to control the engine timer. The BROWN wire should be grounded when the engine is OFF C i.e. C wired through a N.C. contact on a B&C pressure switch C in parallel with the oil pressure warning light. When the BROWN wire's connection to ground is broken C on engine start C the engine timer begins.
So C what the manual says to do doesn't work C and what the manual says not to do is what you have to do to make it work. I suggested to EI that they should at least fix the manual C but they did not indicate any eagerness to do so. Hopefully C this work around will be useful others.
Otherwise C it's a nice clock.
Ron
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