Ray Allen trim calibration

[G-RVMS]

I have a Vans RV-7 with 2 SkyView HDX, SV-AP, SV-Comm, SV-XPDR fitted; power is via a VPX.
Both pitch and roll servos are powered through the SV-AP panel, with the position sensors through the SV-EMS. The problem I have is that when I try to calibrate the trim units, the pitch trim is 4.98v at one extreme and the voltage is erratic until the other extreme, ending at 4.6v (it’s not a linear change, more lick a sawtooth change)
The Roll servo doesn’t change voltage from 4.98v through the whole travel.
I’ve checked continuity and it’s there but wondered what could affect the signal to this degree.
The other thing is that the servos travel for a few seconds and then stop but travel again with the trim button selected again (it takes 4 or 5 selections to travel full length), is this normal?

 

[Bob Y]

Regarding your last issue with run time, sounds like it’s the “runaway trim” feature that you’re activating. See the User Guide.

 

[G-RVMS]

Thanks, yes, I can see that now.
As for my trim servos, I’m beginning to think that it’s dirty contacts in the servo itself; my roll servo has behaved itself after several cycles and the pitch servo has improved - more cycles required. They were delivered as part of the kit over 6 years ago, so may have dirt/dust/corrosion on the potentiometer contacts.