futaba s3156 servos, very jumpy at mid-stick

[istandalone]

i've finished my trex 450 sev2 build, and installed s3156 digital servos on the swash. my problem is when i'm at mid-stick (i noticed the problem when i was setting up for zero pitch/level arms) the servos are pretty jumpy and twitchy. not so bad at full stick or zero stick, but at mid stick when i touch the collective stick they jump. i've added as much as -50 expo with no luck. anyone have any ideas?

[EdgeCrusher]

Using a linear pitch curve, also if your using futaba radio INH or disable Hover Pitch and High/Low ptich may not be directly related but will aid you in avoid further issues.

[istandalone]

by linear, you mean like in a straight line, right? if so, i do have that. i don't think i have hover pitch enabled, but i'll check this afternoon. what do you mean by and High/Low ptich may not be directly related but will aid you in avoid further issues

[EdgeCrusher]

Well lets do this what radio are you using. I just generalized with futaba radio on those Configurations

[istandalone]

oh, sorry. futaba 7c fasst.
also, when flying, this issue is giving my heli what i can only call the "yo-yo" effect. almost impossible to keep a steady alt, and yes i know helis are unstable by nature, but this is worse then i've ever seen. unless i can get this issue ironed out, i'll install hitec hs65's. i've ordered them anyway, but if i can get the digital futaba to work good then i'll stick to them and use the hs65's somewhere else.

[yellowbillycat]

Did you ever resolve this issue?

It sounds like you too have 3156 servos with the "over centering" problem.

So far everyone (and it aint many, 3 including me) that I have found in various forums that have tried these servos, have this same issue. If you watch the arms, they do not return to center, rather they center beyond the true center point, based on the direction of travel.

I'm trying to talk to Futaba about this, but so far, no luck.