PDA

View Full Version : DigiFlight-II ALT HOLD causes climb


Neal@F14
07-09-2010, 11:57 AM
Newly-built RV-8 with DigiFlight-II (the plain, base model). Pressing the ALT HOLD causes the aircraft to enter a brisk climb after about a 3 or 4 second delay.

Any ideas?

Brantel
07-09-2010, 11:59 AM
Is the servo moving backwards?

TrutrakTech
07-09-2010, 12:47 PM
Is the servo moving backwards?

Bingo! Check the servo direction. Engage alt hold on the ground and lift the tail of the aircraft up. The elvevator should move up. I suspect you'll find the servo moves backwards. Check your installation manual for the pitch reversal instructions, it's in the wiring diagram. Thanks!

Neal@F14
07-09-2010, 12:52 PM
Bingo! Check the servo direction. Engage alt hold on the ground and lift the tail of the aircraft up. The elvevator should move up. I suspect you'll find the servo moves backwards. Check your installation manual for the pitch reversal instructions, it's in the wiring diagram. Thanks!

If that's all it is, then the fix will be super easy. The wiring harness for the DF-II came from Stein Air and they included a small loop of yellow wire sticking out the back of the DB-25 connector to cut for pitch servo reversal.

Bob Martin
07-09-2010, 01:24 PM
I don't understand how we got from un-commanded altitude change to reversed servo?? seems like reverse is reversed and won't have anything to do with pitch change.
wait.....after thinking this thru while typing, if the A/P tells the servo to go down but it goes up....then it will tell it to go down more.....and it will go up more...
So I see why it would be a brisk altitude change.....:eek:

wow, never miss a chance to learn something from the Forums!! :D

Neal@F14
07-13-2010, 11:42 AM
Snipping the yellow wire loop fixed the problem. The ALT Hold is rock solid now.

Still have some configs to adjust, such as magnetic calibration, bank angle, etc.

TrutrakTech
07-13-2010, 01:39 PM
Snipping the yellow wire loop fixed the problem. The ALT Hold is rock solid now.

Still have some configs to adjust, such as magnetic calibration, bank angle, etc.

Where's the "thumbs up" smiley when you need it? Glad to hear it's good to go!

Craig23
07-13-2010, 02:41 PM
I was having the same problem with my Digiflight II. I read this thread, snipped the wire on Sunday and now it works great. Thanks.:D