NO apology required Andy. Yes, 3 axis gimbal, and yes, always "Gimbal Off" before landing. (Now the rats! moment) During bench testing, I never connected the gimbal battery. No power below. -m p.s. Sure Gary, I'll try to get a landing and repro shot today.
Probably not, just grasping at straws. It probably would have shown itself. I was wondering about that as well. I am having hard coming up with, why that might be the case. The PDB is a passive device, its getting a ribbon of data from the FC through 12C bus then it unravels it in its independent Atmel 168 chip. Then by knowing its own address by the solder pads on the back of each BL, it sends the appropriate modulation commands to each motor. If there were errors in this it would most likely not allow the BL's to start up without some error. It seems MK does a good job of doing this. Also I would imagine the aircraft would go "bat shit crazy" if this were the case. The only thing that I can I can think of even though some tests have proved inconclusive is that you have dirty channel in RC controller or something on the receiver end. You did mention that it responded once to your yaw commands in clockwise direction but stopped. Even though through kopter tools, it shows it responding correctly, that may not mean that there is not noise being induced on that channel when yawing right. Its possible if the RC not transmitting high enough or modulating a lot unwanted noise when actuating right that it could be getting this noise and the FC could be ignoring the right commands because it sees them being erroneous and not clean for it to say "yes this is intended command from RC yaw stick." The FC has filtering to ignore signal spikes that could induce an uncommanded movement. If its sees the command for yawing right with a bunch of noise it maybe ignoring the command alltogether. Then intermittently sees a clean signal then yaws. That's the only thing that makes most sense, is that it is a RC transmitter issue at this point. A way to rule this out would be to bind the gimbals controller to A/C if they are brand such as a Spectrum you will have solder the DSMX to FC and of course you will need to disconnect the Graupner receiver from the system. If you Graupner on both than its a standard rebind deal. Then bind the a/c to gimbal and see if it respond although the gimbal maybe less persnickety then the MK FC. Shaun
I just realized a quick test that you can do. Reverse the Yaw stick in your RC controller not the through Kopter Tools, but through the controller its self. See if it mirrors the exact opposite response when on the bench. That will be indication that there is an issue with thre RC controller circuitry most likely the potentiometer in the yaw stick.
I thought there was a poll question regarding this that spelled out test specifications. Oh well, I can't find it. Maybe this matter has been resolved. It has been a while since I have had a chance to fly. I tested what I think was not working for the original poster yesterday. I was able to yaw left and right on the ground before and after takeoff. I hope this helps.