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SBach umx RX re-progammed Itself ???

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Stuphedd28/05/2017 18:29:10
736 forum posts
376 photos

Been flying the little Sbach today when on changing the lipo after the second flight , the ailerons stared working in unison , ie they both go up and down together ??

So whats gone wrong ? how do I fix it ??

I have tried binding it to both my Txes , DX8 and DX7 but the result is the same

any ideas please .


Peter Christy28/05/2017 19:03:50
1921 forum posts

I had a similar problem with a UMX Pitts Special, where the elevator decided to reverse itself between flights! That would have been bad enough, but the gyro function was also reversed!!! This implies that the servo itself had reversed direction without warning!

After attempting - and failing - to contact HH service dept, I sent it back, and a replacement arrived a few days later. No explanation, but so far that has behaved itself.

Advice to anyone else flying a UMX Bind'n'Fly: Don't just wiggle the controls before take off - check for correct direction as well!



Stuphedd28/05/2017 22:15:21
736 forum posts
376 photos

Thanks ,

I guess I send it to Germany ???


Denis Watkins29/05/2017 06:00:11
4656 forum posts
132 photos

Pete, is there any way that "wing type", could have been altered in the Tx menu? As this would account for the movement you describe.


Check the servo movements in " monitor " on the Tx, to see the action and remedy the servo sense if needed

Peter Christy29/05/2017 09:17:36
1921 forum posts

Denis: Remember that these models have gyro stabilisation built in. Whilst checking as you say is a good idea, it is not sufficient just to reverse the function at the transmitter, as the gyro function will still be reversed!

In my case, tilting the nose up caused the gyro to add more up elevator instead of correcting with down, resulting in an uncontrolled loop into the ground on take-off!

I thought my instance was a one-off, but it looks as if there is a weakness in the servo design that can cause it to reverse direction. I have no idea how this is possible!

Pete: Mine occurred during the last months of the UK operation, and I sent it back there. I guess now you have no option but to send it back to Germany. During their shut-down period it became almost impossible to get a response from HH UK, the only option was to send it "blind" and hope! Reports vary on how good the German operation is at communication, but in view of the expense of sending it back there, it might be worth an email or phone call first!

Best of luck, and let us know how you get on!



Stuphedd29/05/2017 09:48:48
736 forum posts
376 photos

Thanks for your replys chaps .

Firstly I changed TXes to see if the fault lay there, but the movement is identical with both sets .

The next thing was to reverse one of the aileron servos on the TX, easy I thought , and if the gyros go the "wrong way " I shall swap the servos over , Sorted I thought ,

But reversing either servo just changes the direction of BOTH servos,so at the moment I am stuffed !

Horizon UK were always brilliant, never dealt with Germany , I guess I will soon find out .??

I have a feeling that somehow the 2.4 signal inside my car ???? key fob , blue tooth , got to the Sbach before my TX as I fitted the lipo to the plane inside the boot !

It happened once before , but the elevator went to full deflection so was obvious , and just unplugging the lipo and replugging sorted it !

onwards and upwards I hope !

There must be a method of programming the RX somehow ??

Bob Burton29/05/2017 10:42:34
186 forum posts

"There must be a method of programming the RX somehow ??"

I believe what you need is an SPMA3060 USB interface device from HH. I used it when I moved the electronics from a UMX Sbach into an own design airframe and needed to change the aileron directions.

I had one but lent it to someone on here and haven't had it back yet. Let me know if you think that it will do what you want.

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