J

Jeff Wilde

Member
Greetings, when I painted my panal, I did not mask off my Dynon mounting tray. I got a good bit of paint on it thinking that no one would ever see this. I have studied the posts on Dynon woes and see nothing to indicate where the Dynon unit itself is grounded. I am asking because I get intermittant irratic readings from several of my instruments (tach, oil pressure, CHT to name a few). Is the box grounded to the tray? I hope that is my problem. Any other suggestions? Thanks, Jeff in Florida
 
Grounds

Hi Jeff,

I think Dynon does expect the cage to be grounded to the instrument but there are also numerous other grounds into the box. First, you should grab your ohm meter and check the resistance between dynon and part of the cage that is not painted. Compare this to two points on the dynon for your zero reference. You've probably already thought of that!

Next, do the same for your sensor grounds and, of course, your primary power ground as fluctuating voltage into the dynon will cause the CHTs to move around.

If you can't resolve it with the ohm-meter try dumping the data and seeing if your fluctuations are in synch (common problem) or unique (sensor specific problem).

Finally, you might have a problem with the dynon itself.

Good luck!
 
There is a black wire on pin 3 of the Dynon EFIS 25-pin connector that is connected to the Control Board ground. Is the Control Board grounded per the plans? Additional grounds can be added to pins 3, 5, 13, 16, or 17 of the Dynon D-180 EMS 37-pin connector. However the first thing that I would check is the ground at the battery box. There should be no paint under the ring terminal.

Here is a quote from page 2-2 of the FlightDEK-D180 Installation Guide:
Because of the current drawn by the FlightDEK-D180, even very small resistances between
battery ground and instrument ground can cause voltage differences which adversely affect
engine sensor readings. An easy way to test the quality of the instrument?s ground is to measure
voltage between the ground pin at the FlightDEK-D180 and the ground lead at your aircraft?s
battery. With the FlightDEK-D180 powered on, connect one lead of your voltmeter to a free
ground lead coming from the FlightDEK-D180. Connect the other lead of your voltmeter to the
ground terminal of your battery. The voltage between these two points should measure very
close to 0 mV (within 5 mV). If it does not, you must improve the ground connection between
the ground of your battery and that of your avionics bus.
Click to expand...
Joe Gores
 
Actually I havent tried anything as this thread (the Dynon thread) seems to branch out into lots of directions. I was hoping to save time and effort by having you guys tell me what I have done wrong. But it looks like you guys are going to make me work. I'll check the various grounds and confirm that they are grounding as well as the tray. I'll let you know what I find. It's such a pretty screen. I have another rotax 912 airplane with 4 little round engine guages and I don't remember checking this stuff on that one! Jeff
 
Check all spade connectors

I had the same problem with my EGT readings (both sides) and in both cases, the problem was less than optimal preparation of the wires for the spade connectors. They also have to be very good crimps. I would check anything where you installed spade connectors as a first step.

Jeff
 
grounding

I ran a ground from the Dynon to the floor of the panal and it is now fixed! BTW, I ran all the other checks per the manual and couldn't find a problem. I believe that vibration exacerbated the poor grounding to the tray and was the source of the problem. The moral of this story is to not paint your Dynon tray. Rookie mistake. Thanks for your help all. Jeff
 
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