Pitch Trim readjusting itself. FrSky

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philsson
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Pitch Trim readjusting itself. FrSky

Post by philsson »

It might be a hardware problem. Both pitch and roll keep changing their trims, mostly pitch. The behaviour is the same on two of the copters I have and maybe even on the third but it shows more on the others as I fly them in ACRO. Both machines are trimmed so that relaxed sticks are received at 1500 PWM. One machine is running a D4R-II receiver with PPM signal and the other a V8R7-II where there is a cable to each channel. The module on the radio is the DJT one.
What happens is that the signal in relaxed mode changes suddenly up or down. The difference is so high it affects flying a lot and the copter rotates by itself. The signal can go all the way up to 1580 or the other direction down to 1440 or something. What I do at the moment is to readjust the trim on the 9X but next time I fly, or even during flying it changes. What can it be?
Other mods are that I have telemetry and the 3DR module with bluetooth bridge which is running from its own power supply inside the 9X. I am also using a Lipo.
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Re: Pitch Trim readjusting itself. FrSky

Post by MikeB »

Do you have a switch configured for the "Instant Trim" function?

One of the main screens on er9x shows the servo outputs as percentages from -100.0 to +100.0. Are these changing in the same way?

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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

MikeB wrote:Do you have a switch configured for the "Instant Trim" function?

One of the main screens on er9x shows the servo outputs as percentages from -100.0 to +100.0. Are these changing in the same way?

Mike.
I am not aware of the function you describe. I am adjusting the trims in this menu from picture below. I am not sure if they change in the 9X screen, for starters I think the difference there will be small but maybe I can take a photo of it after trimming and another when it is off to compare.
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Re: Pitch Trim readjusting itself. FrSky

Post by jhsa »

That's not a trim, that is a mix offset which is something different even if it looks like it does the same..
Mike is talking about a MAIN SCREEN, not an edit menu.
There is a main screen with some bars representing the channel positions, and there is another one with numbers. Have a look at the picture attached, this is the screen Mike is talking about..
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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

jhsa wrote:That's not a trim, that is a mix offset which is something different even if it looks like it does the same..
Mike is talking about a MAIN SCREEN, not an edit menu.
There is a main screen with some bars representing the channel positions, and there is another one with numbers. Have a look at the picture attached, this is the screen Mike is talking about..
Okay thanx, so this is where I should trim and not where I am doing it? Guess then I should set all offsets to 0 as well. I thought it was exactly the same =) Or at least maybe it is as I have my mixes in the Flight Controller?
Had my radio on for a while now on my desk together with EZ Gui on the phone. I got readings from 1480 to 1580 without moving anything on the radio on roll channel. Also the bars on the 9X display moved along. Seems like I have something disrupting the analog signal from that gimbal. Throttle and yaw are harder to notice but if they are behaving similar then the values change a lot less there.

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Re: Pitch Trim readjusting itself. FrSky

Post by MikeB »

To check the stick values, go to the DiagAna display (from the main screen, LONG LEFT then UP to highlight DiagAna, then MENU).

For mode 2 (pitch/roll on right stick), A3 is the pitch stick and A4 is the roll. The stick position is shown in two forms, the first is an internal (hexadecimal) value and the second is a number from -100 to +100.
Do these numbers change significantly from 0 over time?

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Re: Pitch Trim readjusting itself. FrSky

Post by jhsa »

Please zero all the offsets, then zero all the trims.

Then go to the screen from my post above, with the numbers.. Then move the sticks to both ends and then back slowly to centre. Take note of the numbers for the Ail and Ele sticks, and post them here please.

João

EDIT: I just saw Mike and I posted at the same time.. Please follow his advice..
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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

MikeB wrote:To check the stick values, go to the DiagAna display (from the main screen, LONG LEFT then UP to highlight DiagAna, then MENU).

For mode 2 (pitch/roll on right stick), A3 is the pitch stick and A4 is the roll. The stick position is shown in two forms, the first is an internal (hexadecimal) value and the second is a number from -100 to +100.
Do these numbers change significantly from 0 over time?

Mike.
I will have that screen open for a while and check. I have done a recalibration of all analog inputs on the radio and for now it looks like this. The input in Cleanflight also attached below.
IMG_20150621_190025.jpg
IMG_20150621_185928.jpg
Screen Shot 2015-06-21 at 19.01.13.png
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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

jhsa wrote:Please zero all the offsets, then zero all the trims.

Then go to the screen from my post above, with the numbers.. Then move the sticks to both ends and then back slowly to centre. Take note of the numbers for the Ail and Ele sticks, and post them here please.

João

EDIT: I just saw Mike and I posted at the same time.. Please follow his advice..
Roll goes from -95 to 97 and pitch -97 to 100.
But any ideas what the problem could be if values keep changing? I mean, even if my settings are wrong they should not change over time right? I am thinking maybe something could be interfering with the analog readings maybe but I don't know if my mods could cause that. And I cant seem to find anyone else experiencing the same problem when I search the web.
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Re: Pitch Trim readjusting itself. FrSky

Post by MikeB »

The starting place is the screen with ANA in the top left corner. These are the actual values of the stick positions. We need to know if they drift away from 0 at all. If they stay at 0, then at least the sticks are being read correctly and we will need to look further "down the line". If these values drift, then we are looking at the stick hardware most likely.

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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

MikeB wrote:The starting place is the screen with ANA in the top left corner. These are the actual values of the stick positions. We need to know if they drift away from 0 at all. If they stay at 0, then at least the sticks are being read correctly and we will need to look further "down the line". If these values drift, then we are looking at the stick hardware most likely.

Mike.
I've been monitoring the correct screen now for as long as I had patience for and it stays at one value for quite long, changes and stays at the new value for quite long and so it goes. I know these controls are analog and just built of potentiometers so what precision could one expect? The value differed from 0 to 6 in the time I've been monitoring it which means a deviation from 1500 to 1526 on the receiver side. It was not so much now, but next time I'm on the field and it differs a lot I will definitely check that screen again to see what the stick value is.
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Re: Pitch Trim readjusting itself. FrSky

Post by MikeB »

I think you will need to open up the radio and check the pots. One possibility is the pot body is not staying fixed.
This is not a problem we have seen particularly before.

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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

MikeB wrote:I think you will need to open up the radio and check the pots. One possibility is the pot body is not staying fixed.
This is not a problem we have seen particularly before.

Mike.
I sure will. Would be nice if it is an easy fix and no further need to examine. I guess the pots can get worn out and need replacement. Googling a little about it I see some people exchange the gimbals for better ones. Maybe that would be an option if they need replacement.
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Re: Pitch Trim readjusting itself. FrSky

Post by jhsa »

Yes the frsky taranis gimbals fit the 9x. And they are not so expensive..

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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

jhsa wrote:Yes the frsky taranis gimbals fit the 9x. And they are not so expensive..

João
Thank you for the advice. I have ordered a pair now. Will post here with the results. Seems like a good upgrade and as you said there is info around that they fit the 9X. Seem to be two versions out there though, one with OP Amp and another without. Though any seems to work as long as you get the cables right. :)
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Re: Pitch Trim readjusting itself. FrSky

Post by jhsa »

I can assure they fit the 9x radio ;) I have a pair installed on one of my 9x radios :)

It seems the one with amp is no longer available. Mine are amplified..

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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

jhsa wrote:I can assure they fit the 9x radio ;) I have a pair installed on one of my 9x radios :)

It seems the one with amp is no longer available. Mine are amplified..

João
Good to know. Also that it does not matter which batch I get, with or without AMPs. Plaid around with the radio a little more and sometimes it flips values, sometimes as high as 18-20 on the Analog screen which result in a signal of almost 1600. This seems to be "fixed" if I shake the stick a little, then it settles at "0" again but this is not a solution. Will be looking forward to my new gimbals. ;)
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Re: Pitch Trim readjusting itself. FrSky

Post by jhsa »

Please let us know if the problem was solved..

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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

Gimbals mounted and dry tested. Maybe some flying tomorrow. Will update you with the results. At least looking good ;)
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Re: Pitch Trim readjusting itself. FrSky

Post by philsson »

I'm the slowest in the world att updating this but call tell everyone this was the source of the problem. Been working flawlessly since July last year. haha..
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Re: Pitch Trim readjusting itself. FrSky

Post by jhsa »

Better late than never :mrgreen:

Thanks ;)

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