Motor pauses at half throttle, then resumes above that.

[Captain Dunsel]

Radio is a Futaba single stick transmitter, converted to 2.4 with a Lemon module and an Ellis simple encoder (done by Radio South). All works fine, except the motor pauses at half-throttle, then resumes above/below it. In other words, I can get (roughly)10 to 40 percent power and 60-100%, but not 50%.
This is happening with two different ESCs, both calibrated to the same receivers (Spektrum AR6210 and an Orange R720). It happens when throttling up and when throttling down. Throttle trim position does affect exactly where the pause occurs.

 

[Foamforce]

Radio is a Futaba single stick transmitter, converted to 2.4 with a Lemon module and an Ellis simple encoder (done by Radio South). All works fine, except the motor pauses at half-throttle, then resumes above/below it. In other words, I can get (roughly)10 to 40 percent power and 60-100%, but not 50%.
This is happening with two different ESCs, both calibrated to the same receivers (Spektrum AR6210 and an Orange R720). It happens when throttling up and when throttling down. Throttle trim position does affect exactly where the pause occurs.

Hook up a servo to the throttle channel and see what it does. I expect it will do the same thing, in which case you likely have some sort of weird mix set up in your radio.

Edit: Ok your radio probably doesn’t do mixes, but it would be on the radio/receiver side if it does the same thing with a servo.

Also, this doesn’t sound like an ESC calibration thing, but you may as well calibrate the ESC just to make sure.

 

[Captain Dunsel]

I did calibrate both ESCs, on both receivers. Same problem on both. I will try a servo, plugging the ESC into another channel. I am getting full servo travel on all the other channels. As this is not a standard Spektrum transmitter, channel order is not the same as Spektrum, so Channel 3 is throttle, not channel 1.

 

[Captain Dunsel]

As Foamforce suggested, I plugged a servo into the throttle channel (with the ESC on the aileron channel, without a motor attached). The servo swings properly through the first ~1/3 of the throw, then starts to gyrate back and forth, from one extreme to the other, until I reach a little over 1/2 throttle. From then on, it moves smoothly up to full. Reversing direction and throttling down, it works the same way, with the same disruption at around 1/2 throttle. Moving the throttle trim up and down does seem to displace the point of disruption.
I'm beginning to think I'll have to re-calibrate the transmitter as it is the only thing in common with both tests; that is, I've swapped ESCs, receivers, motors, and even batteries, but all give the same problem.

 

[AIRFORGE]

Is your throttle control on a separate thumb wheel or a potentiometer on the single stick?
It might be worn or damaged. It may have corrosion or only debris that can be cleaned.
Does it feel gritty or maybe even loose at the point where you're having issue?

 

[Captain Dunsel]

Yes, it's a thumb wheel, top of the transmitter (Red circle. Throttle trim is blue circle). The labels were from before it was converted and are not valid.
No, it doesn't feel gritty. It's ratcheted, but feels about as smooth as the other ratcheted thumb wheeled controls.

 

[Foamforce]

It must be either a bad/dirty potentiometer, or some funny business with the converter, but more likely the potentiometer.

Are the pots for the aileron trims the same as for the throttle? Maybe try swapping them. I’ll bet the problem follows the pot. If the pots are exposed, maybe they could be cleaned with electronics contact cleaner? Don’t take my word for it though, I’ve never tried.

 

[Merv]

...except the motor pauses at half-throttle, then resumes above/below it....

That is what happens when the model is in helli mode. Make sure the model the the Tx is setup in airplane mode. You might need to setup a new model.

 

[AIRFORGE]

That is what happens when the model is in helli mode. Make sure the model the the Tx is setup in airplane mode. You might need to setup a new model.

Good point, brother!

 

[Tench745]

I was thinking the same thing as Foamforce, wouldn't hurt to get some electrical contact cleaner, spray it in there and see if the potentiometer is dirty. It would be handy if you had a way of seeing what signal the radio is seeing from the throttle input

 

[Shurik-1960]

The best option is to open it, look at the marking of the potentiometer and buy a new one. I disassembled the old potentiometers and cleaned them with alcohol- they worked, but not for long: the carbon layer wears out, the slider oxidizes. The new one is the best solution. P.S. I've never seen such a radio control.

 

[Piotrsko]

Boards inside might be stamped futaba, but that case is definitely one off for helicopters. Nice build but futaba is proud of their stuff and wants others to know with labeling.
Pots should have outside(?) gimbals on trim to technically move centering spot, not stand off trim pots relocated to the top. Main stick looks to be offset from square. Like what we used to do before electronic mixing.
Good news, look to be standard slider resistor pots. I would just search for replacements from Mouser since they never respond to cleaning long term, you just end up doing it more often until you wear off the carbon like @Shurik-1960 said

 

[Captain Dunsel]

The case is Futaba, but the electronics are a Ron Ellis Simple Encoder and a Lemon 2.4 module. I contacted the converter (Radio South) and he figures the pot's bad, so I'm sending it back for replacement. I

BTW, the throttle trim works fine, but not the throttle itself. Another clue that it's the throttle pot.