RC India

The other day, I went to the field to fly with my faithful Futaba 8FG . When i powered up my model I noted that it had substantial up elevator. Perplexed, I went to the Servo menu on my radio to see that almost full up elevator was given as a command, even with the stick neutral and the trims almost centered.

The gimbal and stick did not seem to have any mechanical problem, and when i moved the stick the center point changed randomly. The servo bar moved with the stick was usually offset and never centered. It was a very nervous moment - Imagine what this could have done, with comeone flying a multi rotor, only to have it come flying back at them with no stick movement !!
Or for that reason go flying anywhere else !

The stick was smooth, and the radio has had no history of problems or handling problems.

Of course i would never fly with such an equipment, so went home and opened the radio. Everything inside was clean and factory set.

The gimbal was connected to the motherboard with a cable with connectors on each one. One end plugged into the gimbal and the other into the main board. i noted that when I touched these connectors, the servo output varied.

So, I took of the connector, cleaned it with some iso propyl alcohol, and after drying, put it back and all the problems were gone !
The centering works fabulous !

I wrote to Futaba support on RCU and the thread is linked below.

http://www.rcuniverse.com/forum/futaba-radios-direct-support-forum-125/11598036-stick-centering-problem-futaba-8fg-super.html (http://www.rcuniverse.com/forum/futaba-radios-direct-support-forum-125/11598036-stick-centering-problem-futaba-8fg-super.html)

Futaba seems to acknowledge the problem by :
- A Removing the connecotrs in the 8FG super and soldering them
- B Explicitly saying that we should clean the connectors routinely.

Amazing how such a big reputed company can expect people to open up their radios routinely, and take out the delicate connectors and clean them - Plus this never being documented anywhere in maintenance regime !

Perhaps an important thing to note for all current 8FG users.

Cant think of what all damages this can do ! All Futaba 8FG users should be alerted !

That is totally unacceptable  :o  

They should recall all radios and do fixes at their cost.

This has severely dinged my Futaba fanboy-dom !

Guarav, can you also ask in that thread *when* they fixed the issue in production models, and if there is a way to identify which batches are fixed ?

Anwar,
I will ask. But really this was un-nerving. I should have taken a video of it happening. The centering was not just off by one or two points, which would be un-noticeable in flight, but by more than half of the control movement ! Imagine giving half elevator stick up uncommanded !


Futaba should immediately acknowledge this problem, and do a recall/fix for this. Unacceptable to have such a core/serious flaw ! If its happened once it, it would happen again.

@ Gaurav

Gimbal Signal for the stick being generated by the position of Potentiometer connected to the stick axle, this is bound to happen even if there is a small amount of oxidation in the Plug connectors of the potentiometer which will vary the balance of the potentiometer, which can easily happen due to any ingress of moisture, sweat or fuel with Nitro with overtime usage. Only way to eliminate this is to remove the plug connectors and directly soldering the three wires to the main board further to be doubly sure can give a coat of lacquer to the exposed solder conductors.

This has been my major worry every time when we flew in rain  ;) , or when a fuel drops splat on the radio.

@sundaram,

Agreed. But shoudlnt Futaba solder and avoid such a failure point in the first place ? I think this is too basic to be ignored ! The gimbals are not designed to be user replaceble anyways, so why the connector in the first place ?

That I agree with you 100%. Connectors or an added point of contact prone to create errors which can be very much avoided.