Diagnosing crazy altitude problem on a D10A

[kevinh]

Dear Dynon,

I have a D10A in my RV7 - I first flew it in 2005 and I love it.  But... I just encountered a strange problem.  I'd appreciate any guidance you can offer.

Symptoms:
[olist][*]At my 50' elevation field, I dial in a 30.11 baro reading and the altitude display is correct.
[*]Start takeoff roll, on climbout look down and see that the altitude display says -1200(ish) feet.  Also notice that the wind vector display (from airspeed vs GPS correlation) says that the wind is about 70 mph (wind was calm).
[*]Dynon airspeed display is fine.
[*]Conventional 3 1/8" airspeed and VS seem correct.
[*]Notice the problem, fly around the pattern and land. 
[*]In runup area, I power cycle the dynon and after boot it comes up with a default baro setting of 28.77 (presumably because it adjusted the baro to whatever it needed to get -1200').  Change baro back to 30.11, see that the altitude display is correct again at 50'.
[*]Take off, same problem happens.  Land.
[*]Taxi back to hangar and feel various pitot/static lines behind the panel - they feel okay.
[*]Make this post 
[/olist]
Any tips on what could be causing this new behavior?  Other relevant datapoints:
[olist][*]About 400 hrs on the unit.
[*]This was the _second_ flight after maintenance where I removed my primary panel (disconnecting and reconnecting pitot, static and AOA lines.  These lines are routed to the dynon, an Altrak, a VS and an airspeed indicator).  I use the dynon as my altimeter.
[*]The previous flight was fine - flew for about an hour with no problems.
[/olist]
I'm not suspecting the Dynon per se but possibly a system problem.

 

[dynonsupport]

Either something is pressurizing the static port on the Dynon (for example, if the pitot or AOA lines are accidentally connected to the static port), but if that were the case, you probably would've noticed it on the first flight.

Else, likely something is going on with SkyView's altitude sensing capability, and we'd need to see the unit here.

 

[globox95]

hi all,
what was the issue of this problem ?
i had the same problem yesterday with my D10A after 4 month off. when i start the D10A, the altitude was right but when i start the motor, the altitude falldown to -1200 ft.
I check all the static lines wich seems good but cant do an another test due to MTO :-( i dont have an other altimeter to check if it is the D10A or the static line :-(.
is the altidude of the D10A works only with static or it use informations calculated from Pitot ? (my AOA is not connected). My D10a have 20 hours since new working well before this problem ...
regards