Oh the sinking feeling 
Below is the message I sent to Dynon Support. Posting here in case anyone has some insight/advice in the interim:
I just received my D10A (Serial # 005768) and got right to work installing it in my RV4. Love the new display over the older ones I’ve seen! Very sharp! Also sharp was the acute sickness I felt in my stomach (after I apparently shorted it) when I hooked up the wiring harness for the first time. I hope it’s just an internal fuse?!
After I got the EDC-10A mounted and wired to the Connector along with the OAT, I decided to momentarily plug in the wiring harness to the back of the EFIS to check the compass connection. I plugged in the harness with aircraft power off. I looked to make sure no wire ends were stripped and draped all the wires over to the side of the fuselage (including the power wires which were not connected yet) to prevent any potential shorting. So the only part of the D10A harness in the avionics bay was the EDC cable which was now connected at both ends.
I turned on the D10A with the button to bring it up on battery power. I almost immediately had a heading indication at the top which was about right for the orientation of the plane. I heard what I thought was a very faint arcing sound somewhere so I quickly pushed the button to turn off the unit. I’m not sure if it shorted out first or if I shut it off, but it will not come back on. I tried disconnecting the internal battery and bringing up on ship’s power after hooking up harness to CB and ground (and bagging all other wire ends!) Applied ship’s power with battery disco’d (verified 12.8 volts at D25 Pins 1 and 3) and still nothing.
The three possibilities I can come up with are:
1. I noticed after the fact that the wires draped over the fuselage curved just perfectly in such a way that the .002-.003” of conductor that protruded where they (had been cut apparently with dikes leaving a little ridge) were actually making contact with the aluminum skin! Could they have shorted even on the painted aluminum? I couldn’t find any physical evidence of arcing anywhere.
2. Short in EDC-10A (probably not likely)
3. Made a mistake wiring the Connector. I checked all the wiring from the EDC even though I had triple checked it before hookup. I took it back apart to see if somehow a strand of shielding poked into another conductor or migrated somewhere – seemed fine. I checked for continuity between pins on the EDC connector – no connections were shorted to one another. Pin checked again between EDC connector and EFIS’ D25 – continuity pin to pin all were good except one thing perplexes me. When checking between EDC Connector Pin 1, (3-way ground with blue wire, shield and white wire soldered together) and D25 – I get continuity at D25 pins 3, (main grd) and 24 (EDC grd) as expected. At pin 1 – main power, I get 700 Ohms?
Obviously my goals are to get the unit in and fixed as soon as possible. And, be absolutely sure what caused the short so I don’t have a recurrence. If the cause is not obvious from what I’ve reported about the EDC wiring, maybe you can tell when you open it up where the errant juice came from by what was affected?
Below is the message I sent to Dynon Support. Posting here in case anyone has some insight/advice in the interim:
I just received my D10A (Serial # 005768) and got right to work installing it in my RV4. Love the new display over the older ones I’ve seen! Very sharp! Also sharp was the acute sickness I felt in my stomach (after I apparently shorted it) when I hooked up the wiring harness for the first time. I hope it’s just an internal fuse?!
After I got the EDC-10A mounted and wired to the Connector along with the OAT, I decided to momentarily plug in the wiring harness to the back of the EFIS to check the compass connection. I plugged in the harness with aircraft power off. I looked to make sure no wire ends were stripped and draped all the wires over to the side of the fuselage (including the power wires which were not connected yet) to prevent any potential shorting. So the only part of the D10A harness in the avionics bay was the EDC cable which was now connected at both ends.
I turned on the D10A with the button to bring it up on battery power. I almost immediately had a heading indication at the top which was about right for the orientation of the plane. I heard what I thought was a very faint arcing sound somewhere so I quickly pushed the button to turn off the unit. I’m not sure if it shorted out first or if I shut it off, but it will not come back on. I tried disconnecting the internal battery and bringing up on ship’s power after hooking up harness to CB and ground (and bagging all other wire ends!) Applied ship’s power with battery disco’d (verified 12.8 volts at D25 Pins 1 and 3) and still nothing.
The three possibilities I can come up with are:
1. I noticed after the fact that the wires draped over the fuselage curved just perfectly in such a way that the .002-.003” of conductor that protruded where they (had been cut apparently with dikes leaving a little ridge) were actually making contact with the aluminum skin! Could they have shorted even on the painted aluminum? I couldn’t find any physical evidence of arcing anywhere.
2. Short in EDC-10A (probably not likely)
3. Made a mistake wiring the Connector. I checked all the wiring from the EDC even though I had triple checked it before hookup. I took it back apart to see if somehow a strand of shielding poked into another conductor or migrated somewhere – seemed fine. I checked for continuity between pins on the EDC connector – no connections were shorted to one another. Pin checked again between EDC connector and EFIS’ D25 – continuity pin to pin all were good except one thing perplexes me. When checking between EDC Connector Pin 1, (3-way ground with blue wire, shield and white wire soldered together) and D25 – I get continuity at D25 pins 3, (main grd) and 24 (EDC grd) as expected. At pin 1 – main power, I get 700 Ohms?
Obviously my goals are to get the unit in and fixed as soon as possible. And, be absolutely sure what caused the short so I don’t have a recurrence. If the cause is not obvious from what I’ve reported about the EDC wiring, maybe you can tell when you open it up where the errant juice came from by what was affected?
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