Strange servo problem with MKS DS-92a+ with FL760

[olvesh]

I recently bought a used trex 450 SE v2 with RJX head and Fl760 flybarless system. On one of my first trainings the crosswind blew my heli into a hedge and a servo HK-933 lost its teeth (and gear plus tail fin). I (now) know I shouldn't train in the wind :-/

Seeing this as a good opportunity to spend too much money compared to my skills I bought three MKS DS-92a+ as they are fast enough for flybarless and seems solid.

Problem is that my aileron servo is not initializing, and the problem follows the port on the fl760 controller (i.e. the servo works, not the port). If I plug the servo into th RX it works.

Now for the strange part: if I swap the rudder (Align DS-420) and the aileron ports, both work! Now I got confused, so I plugged in an old HK-933 and it also works.

This means that everything works, just not my three brand new MKS DS-92a+ together.

I have tried both 5v and 6v from my HobbyWing Platinium 40 A.
I have pinched and squeezed the wires from the fl760.

My RX is an Orange DSM2 from HobbyKing.

Any suggestions for a desperate 450-beginner?

(apologies for any double-posts, I tried posting through Tapatalk on my iPad, but it didn't work - yet)

Regards,
Olve

[phoenixtechuk]

Hi Olve,

We had a similar case with fl760, just waiting a reply from mks Canada pilot, he is use the 760 and 540, good to know what he say.

thanks
andy

[olvesh]

Thank you for the notice Andy..

I am speculating here - but for the cyclic on the FL760 only the aileron plug draws power from the RX (the rudder is fully wired). Is that a coincidence? Does the three MKS servos draw more power than the aileron port on my RX/FL760 can handle?

I will try to swap out my Orange RX with an AR6115 from Spektrum (borrowed) to see if that can have anything to do with this.

[olvesh]

Have now tested with the Spektrum RX, and the problem persists. It seems that I can't use my new servos with the FL760 :-(

If anyone have some tricks up their sleeve for my problem, I would be very grateful! My only solution at the moment seems to be to buy another FBL system. Or might it be an error on the servos so they consume too much power?

This servo upgrade is really turning out to be much more expensive than I expected.

Thanks,
Olve

[olvesh]

Today I build a sort-of female-female-male y-harness to be able to feed the servo power directly from the RX while piping the signal through the FL760. The servo is still not initializing, so it is not a power problem..

I think I have to conclude that the MKS DS-92a+ is not compatible with the FL760, or that my FL760 is somehow faulty (although it works with other servos).

So I have now put all my faith in Andy that he comes up with a solution. :-) Or I just might drop by my local hobby shop and buy an overpriced BeastX FBL instead...

[olvesh]

Problem solved! The BeastX Spektrum combo did it, although a "little" more expensive than the solution I set out for…