Left gimbal (THR / RUDD) erratic output

Last night I attempted the A7105 module installation. I had an issue where the vibration motor ran constantly but that resolved itself once I selected the Flysky module (see my other thread on that). The A7105 appears to be working normally and I can bind and control my V929. The problem is that last night the Rudder output was erratic (left / right on left gimbal). Now this morning the Throttle gimbal is showing the same erratic output in addition to the rudder. In the channel output monitor the levels for Ch4 (Rudder) and now Ch3 (throttle) dance up and down by about 20-40. I've tried calibration but all that really does is center the range that the levels are dancing around at 0.

Obviously it's impossible to fly anything in this state. I thought maybe I had a bad pickup on the rudder but now that the throttle is doing it as well I really don't know what to think. Any help or suggestions of what to try would be greatly appreciated!

Hiya!

I was having the same behavior, but everywhere.... try loosing the gymbal springs!

Cheers!
-=S=-

FDR wrote: Check the plugs of the pots on the PCB for any contact problems first...

I assume you mean the 3 wire (red, yellow, black) plugs that plug into the main board? If so, I've unplugged, checked, cleaned with alcohol, plugged, checked and double checked at least 10 times. If you mean something else then please explain (I'm not always the sharpest tool in the shed)

Scream wrote: Hiya!

I was having the same behavior, but everywhere.... try loosing the gymbal springs!

Cheers!
-=S=-

I'll give that a shot, I don't see how the springs could cause +/- 40% variance I'm seeing but at this point I'll try anything.


I checked the channel monitor with the stick inputs (left stick) unplugged and neither channel moved at all so the issue certainly appears to be in the sticks / pots and not in the main board.

Well it certainly isn't the spring tension. In fact it appears I was wrong in my previous post. It doesn't appear to be the pots after all. I removed the gimbals and tested the potentiometers with my multimeter and they are dead on and the resistance isn't fluctuating at all on either of them.

I decided to remove the A7105 module and eliminate that as a possible factor (I also disabled it in the .ini file) Unfortunately that didn't solve the problem. I've inspected the connections to the pots and inspected and cleaned both sides of the board. There are no visible shorts or anything like that.

I'm really at a loss. I'm probably going to try flashing back to the stock firmware and see what that does although I really don't have high hopes.

Any thoughts / suggestions would be greatly appreciated.

Thanks for the response PB. I did flash back to stock however I couldn't find any sort of channel monitor to know if the problem exists there or not and I don't have any helis I can fly with the stock firmware. Do you know if there is a channel monitor of something similar in the stock firmware? I flashed back to Deviation 3.0.0 and the problem was still there.

Tonight I removed the main board and thoroughly cleaned and inspected it and blew it off with compressed air. I checked that all connections were tight when re-assembling. I performed a calibration but still the issue persists.

The Rudder channel is the worst however the throttle is still moving around as well without input from the stick.

It's like the center point is moving. Stick movement clearly registers but I can't go all the way to 100 (for rudder), full right is like 80 and I reach -100 well before the stick is fully left. The "center" typically shows anywhere from -40 to around 0 but mostly between -20 to -25. The throttle has a similar issue only reaching about 80 on the high end and reaching -100 before it should on the low end. Keep in mind this is seconds after a full calibration. I can see it start centered at 0 and sporadically "drift" away. Makes we wonder if I have a bad ground somewhere that is floating up a little or perhaps weak power that is being pulled down? I have swapped batteries (fully charged NiMH) to no affect other than the voltage displayed on the screen being higher...

Thanks again for the help with this issue. I really love Deviation and the Devo 10 and I hate not being able to fly or even practice on Phoenix. I was able to re-install the A7105 into the V929 remote so at least I can fly that. If I do even attempt the mod again I get one from Ali Express.

I flashed back to stock again and this time found the monitor (don't know how I missed it before). Anyway, the problem is still present on stock so it is definitely not related to Deviation (not that I ever thought it was).

PhracturedBlue wrote: Have you tried it with the gimbals unplugged, or reversed? It would be useful to confirm the issue is on the board.

I tried it with gimbals plugged and unplugged and I've actually taken out the pots and measured them with a multimeter. Issue is still present with gimbals unplugged and both pots measure as expected.

PhracturedBlue wrote: Also, what are you using as a battery? The A/D circuitry is potentially very sensitive to the stability of the reference volatge.

I'm using eight Sanyo Eneloop NiMH batteries and I have tried replacing with freshly charged batteries but with no change.

On the -100 to 100 scale it would vary in upwards of 40 points. I don't think you could filter out a 20% variance and be left with anything usable. I've exhausted all I know to do and will be sending it back.

I've worked in electronics manufacturing for over 10 years. This is a dead simple mod and I know I didn't botch it. I really have no idea what happened. I've ordered a new Devo 10 that should be here on Friday. Perhaps at some point I'll try the mod again, it would be really nice to be able to fly my V929 with the Devo, but for now I think I'll just be happy with the stock remote.

I cleaned both sides of the main board with isopropyl alcohol and a brush / swab and compressed air then inspected under magnification. It's probably the cleanest Devo board in history.

as much as I hate to admit it I've given up on this one.

Hi there.

I had exactly the same problem with the throttle on my Devo 12S.
My Devo 12S is brand new and I was planing to use it on a 700e DFC.
After this issue came out I got really worried on using this transmitter in a 700e which could generates a serious accident.
Anyway I found the problem... The cable (sginal cable) that connects the potentiometer to the Throttle pin on the MB was too loose. In fact the three cables fit pretty loose and seem to be of a poor quality... After I tightened the pins with a pliers, the issue desapeared...

Hope this can help.

Bumping an old thread here.
I had the similar problem with a Devo 10 elevator gimbal. About half the time when I centered it it would drift to -30 over about 5 seconds. I took the potentiometer out and cleaned it with Deoxit D5 and the problem went away.
To clean it I pointed the back side up and put a pool of Deoxit on top of it and worked the shaft for a couple of minutes. Then sprayed around the shaft on the front side and worked it for a couple of minutes. I re-installed it and it was a steady -4 when centered, so I re-calibrated the gimbals and it works great now. I got the Deoxit from Radio Shack.
The potentiometer looks just like these: www.aliexpress.com/item/SA-Japanese-NOBL...10MM/1302569488.html
These are 5K, mine measured 4.5K.

BirdBarber wrote: I got the Deoxit from Radio Shack.

R.I.P. In retrospect, trying to turn into a big box electronics store at a time when big box electronics stores were dying out was not a smart move.

So where do you get it now?

mwm wrote:

BirdBarber wrote: I got the Deoxit from Radio Shack.

R.I.P. In retrospect, trying to turn into a big box electronics store at a time when big box electronics stores were dying out was not a smart move.

So where do you get it now?

They are in chapter 11 reorganization, not full on chapter 7 liquidation bankruptcy. They are only closing some of their stores. And it's still available on the Radio Shack web site. But I would hurry if I were you, lol. Amazon used to sell it also.