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ST16 Control Stick Problems

Aug 23, 2016
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Ok guys it seems there are serious problem with the control stick programing on the ST16's.. I have been told by Yuneec my st16 needs the control sticks replaced and then the repair shops get it and they say its not the sticks its a firmware problem.. 3 times.. each time it comes back and works good for a few weeks then here we go again.. This time its the forward and back stick movement... When I got it back I went out to give it a test flight and it would only creep forward and back so when I got it back on the ground I went into the Hardware Monitor and sure enough the forward and back stick gage shows the stick response moving real slow again and only going to 30% throw at full stick... I called Yuneec and after only a 30min wait I talked to a repair tech who went threw all my work orders and due to not being under warranty any longer he agreed he would send me a set of control stick units so I could replace them and at the same time have a look to see if we can figure out what's going on with the potentiometers.. I received the control sticks in 4 business days and set down today to change them out.. Before taking the transmitter apart I decided to watch a few of the YouTube videos showing how to disassemble the transmitter and also stumbled across Richard Gilmore's video showing how his K1 Pan knob some how got mixed to his J1 up and down controls.. So I went back in to the Hardware Monitor and tried moving each control and low and behold I found that when I move my J2 yaw stick left and right my J3 control gage moves real slow also.. Full left yaw J2 stick causes the J3 stick gage to move forward to 25% .. This mixing that keeps happening to everyone could be a major cause of fly aways and crashes... Like you said Richard if you had turned K1 a little farther she would have dropped out of the sky!!!!! So now the question is what can be done to stop this from happening.. Does anyone know how to turn on and off mixing in the ST16?? I will be calling Yuneec on Monday morning and will post what they say here on this thread.. If you have control stick problems we could all post on this thread and maybe we can keep track at what's going on to solve this problem....
Does anyone know how to turn on and off mixing in the ST16?
The problems you are having (2) have both been documented well in this forum. Both are an easy fix once you identify the problem.
We'll start with the mixing issue:
Go to the opening page of Channel Settings. It should look exactly like this:
If it does not, tell us what it looks like. Note: Do not press anything on the left side of that screen. Only the right side.

The pots get oxidation rather easily. Before each flight it's a good practice to "stir" the sticks in a circle to help clean them. Then check in Hardware Monitor to see if they look correct.
When you look at them in Hardware Monitor, if they appear sluggish, don't return to exactly zero or appear erratic, they need cleaned. Pick up a spray can of Electrical Contact Cleaner that says "Safer for Plastic" "Leaves no Residue".

There are three ways to clean them.
1. Spray a the base of the sticks and keep moving them in all directions. You may need to do it several times.
2. On the back of the ST16 there is a small hole over each stick. If there is a rubber plug, remove it. Spray and stir.
3. If you have the ST16 open you can spray the pots directly. Again, spray and stir.
Recheck in HM to make certain they are working properly.

Obviously, don't attempt to fly until both of these issues are resolved.
We will stay with you on this until everything is working properly. It's up to you if you wish to call Yuneec again but honestly we've been through this so many times it will be faster and more efficient to stay here. Many of us have more experience dealing with this than the techs.

The base of the sticks look like this and the pots are shown:
Left Stick pots.jpg
Last edited:
You may need to “reset” anything you attempted to change and a firmware reinstall will do that.
It received a complete firmware update at United Radio and flew flawless when I got it back .. it set for two weeks before I went to fly again again and it had no forward or back control.. now I find with further examination it has mixing between the yaw control and the forward and back controls.. can bad potentiometers cause this.. ???? I love the H package but why do things keep changing in the transmitter? I hope to have time today to go in and check the pot connection points.. is there something that could cause this mixing to occur? ???
My channel settings do not show the mix on the boxes on left side of screen..
Not unless you hit buttons on the left first. That can lock things into mix state and link the sticks. I did that first time messing with control editing. Again, a firmware reinstall will put it all back.
I recently purchased a used TH and it’s ST was a mess. Nothing was proper and it needed a full maintenance and calibration to get working. The problem was not obvious in hardware monitor. I had to look at stick travel on each parameter in the edit section. It took ST firmware reload direct from SD card, air, contact cleaner, lots of wiggling and two calibrations before I got the sticks centered reliably. I remember well my frustration learning the H idiosyncratic behaviors but now they are routine maintenance procedures. Take a breath and believe more in your skills and look less towards it being broken and try again.
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So I guess so far no one has figured out how to turn mixing on and off without having to do a complete firmware reset on the Transmitter?
Again, there is reset on every part of the control edit windows. The firmware is just quicker and will reset everything. The only thing that should be linked in mode2 is J1 and B1 when looking at the throttle (channel one and top left box in right side columns) and that’s it. You are saying your rudder and elevator are mixed if I understand your problem correctly. Don’t forget flight mode is different stick layout and most of us fly mode 2 on the H as that’s the normal stick behavior most Drones follow.
So I guess so far no one has figured out how to turn mixing on and off without having to do a complete firmware reset on the Transmitter?
To be clear......mixing on the same stick can be a pot issue. Mixing channels from one stick to the other can only be channel mixing.

In your case, I recommend going to Pad, Settings and do a factory reset. That will assure no mixing is taking place. Then create a new model and re-bind.

Do the stick cleaning procedure to fix the erratic sticks. Recheck everything and you should be back in business. Always "stir" the sticks before starting the H.
So what do you think caused this mixing to occur? Especially mixing from one stick to another? Is there a higher quality potentiometer that we could use? I would like to eliminate the problem instead of worrying about reoccurring chances of crashing due to equipment failure..
So what do you think caused this mixing to occur? Especially mixing from one stick to another? Is there a higher quality potentiometer that we could use? I would like to eliminate the problem instead of worrying about reoccurring chances of crashing due to equipment failure..
If the sticks are mixed it should be evident in the Channel Settings. There are two channels for each stick. You can select them on the Right side of the Screen and the left side should show you which stick is on that channel.
Thr- J1, B1
Ail - J4
Ele - J3
Rud - J2

Never select anything on the left side of the screen. Only the right side.
When you select the channel on the right side, you should see the graph change only for the stick highlighted when you move that stick.
Well after a little research this evening I found a few things with the potentiometers on the ST16.. With my H and transmitter being shipped to three different repair shops I cant say who did what but it seems they know the connectors on the potentiometers are a problem because they used what looked like hot glue on the Elevator and Aileron potentiometer connectors... But when I looked at the Throttle and Rudder stick Potentiometer connectors I found the Rudder Pot connector had been glued with a black rubber like glue and there was nothing on the Throttle Pot Connector.. This connector was loose as far as when I moved the wire the connector would wiggle on the pins... I then applied a connector fix that I have done for years and that is slightly bending one of the outside pins in an outward direction and the other pins in the other direction.. Warning bend only slightly.. When I plugged it back in it would not wiggle at all.. I then put the battery wire back through the back of the transmitter and slid the transmitter halves back together.. Installed battery and turned it on.. Went to Hardware Monitor and found no more sluggish elevator stick or mixing between Rudder and Elevator sticks... I also found there is a small hole in the potentiometers that to me looks like it is there to be able to spray air in to clean the Pot's.. Not sure spraying air cleaner through the stick area will get into the Potentiometers.. but I do believe that when your doing the stick wiggle your moving the wires causing the loose connectors to re-establish temporary connection... I think these connectors need some kind of clip to hold them tight.. The wires are constantly moving with stick movement so without clips I think they will continue to create connection loss and then who knows what control loss or mixing might occur.. Wouldn't it be something if all the control loss fly-away's have been caused by a simple little connector.. I didn't glue my loose connector because I'm going to check it again after I get some flying in and see if it comes loose again.. Also looking into why there is even a connector at the pot?? Well its time to move the sticks and get some flying in.. I'll report back soon.. ST16 Stick Poteniometer (2) - Copy.jpg ST16 Stick Poteniometer (4) - Copy.jpg ST16 Stick Poteniometer (10) - Copy.jpg ST16 Stick Poteniometer (12) - Copy.jpg ST16 Stick Poteniometer (8) - Copy.jpg
You have been busy.
The connectors on the pots generally have a sealant or glue applied but sometimes only the pot that moves with the gimbal has it. The other pot is stationary so the wires do not move with the gimbal. I the pics below are two replacement sticks, which are shipped with the wires attached, and you can see that one stick has both pots glued and the other stick, only one pot. These were in the same bag as a set of replacements.

The tiny hole in the end of the pot is a perfect location to spray the contact cleaner when you have the ST16 open. Air is not likely to remove oxidation. I would suggest you spray both sticks before closing up the ST16. They have proven to be inconsistent once they are oxidized and will work one time and not the next. Following a cleaning they seem to operate for a long time with no problems. You can expect to see this problem when the controller is not used for long periods.

Question: did you check the channels I listed above?

20180411_005917.jpg 20180411_010033.jpg
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Checked all channels and found everything on the left of the screen correct.. I believe the connector that was not glued and the potentiometers are playing a big roll in a lot of the problems we are having.. Which in turn falls back on the quality of the parts being used and the reason is the lack of quality control being used when these parts are manufactured.. I'm going to look into performing a few test which include (1) the connector test by eliminating the connector and soldering the wires straight to the Pot.. (2) Seeing if there is a better potentiometer that isn't so susceptible to outside conditions..
Thanks Steve for all the help.. Input from everyone is the only way to help get problems solved!!! This is a Great forum!! I will be back with some results soon....
@fly101, I'm curious where you stand with your project??
Hi Steve, All I did was fix the one loose connector and put it back together.. I didn't spray the pots.. I Now have three flights we're I've flown full batteries down to just past first battery warning.. No problems.. Now we are looking at the Same scenario like last time.. I flew a few times and now we have had rain for several days so I will see how things look when the rain leaves the area in a day or two.. One of the other things I was concerned with was that the controller has fans sucking outside air through the transmitter.. That means if the outside air is damp then the fans are sucking damp air through the inside of the transmitter... If the airflow is needed should there be some type of filter to help avoid sucking the moisture through the transmitter??
If the airflow is needed should there be some type of filter to help avoid sucking the moisture through the transmitter??
The air flow is for cooling and it is definitely needed. Some of the components get quite warm. It seems, for the most part, the sticks are the most common problem and I think it's mainly oxidation. ST16's that are used regularly have fewer problems than those which sit on the shelf for long periods of time. That also would explain why new sticks often need cleaned since they may have been sitting in a warehouse for a long time.

It's always a good practice to "stir" the sticks before flying and to also check them in hardware monitor.
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