Problem with 1080 deg Potentiometer

September 20, 2020

Hi all,

I have a 3-axis trim controller with 3 x 1080 degree (3-turn) precision pots. One of the three axis -the one I have mapped to ailerons, won't center properly. The range on all 3 pots is -511 to +509. The other two axes are fine and calibrate great. After I calibrate in Windows I can see the center is off and when I check in DIView I see when I rotate the problem axis half-way (1.5 turns) it reads out at 70% on DIView. When I set it at 50% on DIView there is only about 1/2 turn before I hit the minimum range. So when I'm trimming right it's nice and smooth and slow. When I trim left of center it rolls like crazy. DIVView won't let me input negative values for the minimum. It validates and prohibits entries outside of 0-655. So I can't reset the center without losing almost a full turn of travel.

Here are 4 screenshots from DIView showing the output at 1.5 turns, 0.5 turns, 1.5 turns, full left at 0 turns and full right at 3 turns.

I would appreciate any ideas on what the issue is and how I can fix it.

Thanks,