The hits just keep coming.

4 hours.

I got the EFIS back from MGL on Saturday, with a new display board and the latest software update.   I installed it, with a few changes to the panel:  I added a power switch for the EFIS and I finally got around to wiring up an alternator warning LED.   I have no idea if it works or not, but it’s one less unterminated wire floating around.   Everything works fine, with one weird exception:   With the IOX plugged into the second LAN port, I lose sensor data after about 3 minutes of operation.   Needless to say, this is unacceptable.

First, a little background.   The IOX is the IO eXtender, a box that takes a bunch of analog and digital inputs and feeds them to the EFIS.   These are used to drive things like a CDI, or in my case, trim position indicators.   The RAC trim servo has an output wire that gives you trim position based on potential to ground.   This works OK, as long as the radio, the audio panel, and the transponder are off.   If any of those are turned on, the sensor data from the AHRS and magnetometer go away after a while.   It truly is one of the weirdest things I’ve ever seen.   The only thing I can think of is that the secured supply output on the back of the EFIS doesn’t have enough juice to run both the sensors, the RDAC (engine sensor module), and the IOX all at once.   Acccording to the docs, all those things shouldn’t add up to more than half an amp, wich is the max output of the secured supply.

When I get back from Seattle, (Redmond, actually), I’ll try connecting the IOX to bus power and see if the issue goes away.   I really hope so.   This is really driving me nuts, and I can’t have my flight data interrupted, ever.

Another issue I’ve got is that my altitude-encoding transponder seems to be reading data from the EFIS, but it’s totally wrong:  There is no way pressure altitude can be -200 after I change the pressure setting on the EFIS to show a reading of 3500ft MSL.

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