I left off on Saturday with the two roll transducers working sporadically after centering the calibration screws. I bought an air pressure gauge but my old one is just as accurate so I think I will take the new one back to Home Depot.
This evening I booted up and behold – the right roll transducer was working good! I did a field calibration on it but it wasn’t far off. I couldn’t get the left one to work. It is sporadic. If I apply signal voltage it will start pushing air but if I turn off the signal it will not stop. Span calibration seemed to have no effect. Zero calibration was sporadic (kept getting a pressure signal with no signal voltage).
I ordered a 500-EH replacement from the Valve Store Online. Good prices, reasonable shipping rates, and they even take PayPal. The 500-EH only has a 12ma at +10V lead and ground (no supply voltage loop). Also, the air consumption is next to nothing. The mechanism is different than the other ones but it will let me go up to 145 PSI if I wanted to. Depending on how much I love this new unit I will look forward to replacing the old ones when the time comes.
Finally, the control program. It isn’t smart enough. I basically need the autopilot kind of trend analysis and trim logic for the platform. If it is off balance it never fully recovers to level… ever. So I guess I will work on that while the new transducer is on it’s way. EDD is 5/7.