servo movement not equal

[MadScientist]

i seem to be having an issue on my 4 wheel steer car.

the servo that i set up in the rear does not seem to travel in the negative direction as far as it does in the positive direction

i have checked the "mechanical" center on the servo lined up the servo saver and the tie rod links to "align the wheels" Im pretty sure mechanically everything is good.

Also, the transmitter is commanding -100% so its not a mixing issue that is causing this.
in the positive direction the center of the servo moves approx 87 degrees, in the negative, it only moves about 65 degrees...

Any ideas what i need to do here?

[ShowMaster]

Does this happen to another servo in the same channel?
Things to also try.
Have you tried setting up a totally new model memory and trying that?
I had a corrupted model memory and it acted that way for throttle. I thought I had a bad pot. The new memory worked so I deleted the original one and loaded my setting back in manually and it also worked normally. As I remember the screen showed normal throws. It's been a while but worth a try.
SM


Sent from my iPod touch using Tapatalk.

[MadScientist]

one servo, one channel. as much trouble as i had with this controller and flashing it, im not interested in fixing it right now. its a school project and due in the morning. Ill be buying a different controller for my personal one, thats for sure.

[jhsa]

I'm curious about your problem.. could you please post your eeprom here? and try a different servo if you can..

Joao

I've been offered a known brand radio a little while ago and I refused it.. Thinking better I should have accepted and then sell it

[Rob Thomson]

I suspect just a servo needing reversing.

Hardly an issue.

If you do everything in eepe/companion things will never 100 percent tie to the exact model configuration.

Different servo orientations are likely to make the difference - and tweaking will be required.

Sent from my GT-I9300 using Tapatalk 2

[Flaps 30]

If the 9X firmware (whatever flavour) caused the servo to exhibit this problem. You could be sure that it would have been found and sorted many moons ago, and we all would have suffered this problem.

Let's say that the issue is with the servo for now and we need a way to equalise things up. This can be done by using the limits menu on the TX. Just limit down the side that is going to 87 degrees. You could turn on the extended limits in the model setup. That will let you go out to 125%..

[ShowMaster]

What saddens me is reading posts that end in "I'm going to buy a good known radio" after they usually had a good 9x that they worked on and now it's bad.
Of course they're frustrated and upset but I hate to read that it's the 9x's fault.
Hopefully he'll give us a chance to help him fix his 9x and learn as he does.
That or sell it here for others to fix or use for parts if it is replaced.

BTW, I got a pm from another different frustrated 9x owner and I think we're going to save his 9x and keep him as a forum member. Good news all around.
SM


Sent from my iPod touch using Tapatalk.

[jhsa]

Just a question.. Did you use sub-trim/offset on the servo channel? how much?

[Flaps 30]

I agree with your thoughts Showmaster. Rather sad in many ways.

Just a question.. Did you use sub-trim/offset on the servo channel? how much?

Yes I do wonder if the centre point of the stick was at or near zero before it was all aligned mechanically and if that mechanical centre changed for whatever reason before powering up again.

[jhsa]

what I think is if he has the limits set to -100 / 100 and apply subtrim one side will have more travel than the other because the limits. in that case it is better to enable the extended limits and then use the dual rate to limit the travel equally if it is too much

Joao

[ShowMaster]

Speaking of replacing a 9x with another radio.
I just got an email from Allen at Frsky saying the Taranis will be sent to the dealers by the end of the month with the next batch to follow. Maybe a way to go for this frustrated 9x owner.
I hope he hangs on there long enough for us to all find out what's wrong with his. I think we all enjoy a good mystery to solve, well maybe not him.
SM


Sent from my iPod touch using Tapatalk.

[MadScientist]

just read all these comments. i wish i had the 9x. i have the 9xr. just getting it to take the eeprom and firmware was a pita. I didnt use any trims at all. the only limit that was changed was channel 1, so the the front wheels would turn the same angle as the rear. (lower to 80 from 100)

im going to try another servo.

i dont really want to band aid the problem by fooling the controller with extended limits. id rather figure out why 100 in one direction, doesnt equal 100 in the other direction, when the mix and the mechancis are all centered.

and yes, all the sticks were properly calibrated.

[jhsa]

Are you using er9x or openTX? In openTX there's an option tha you can check when downloading the firmware that shows the value of the pulse being sent for the selected channel. It's in the limits menu.. I think now is called servos menu. on my radio with all centered and limits on -100/+100. the values are 988 uS to 2012 uS.
João

[MadScientist]

er9x

[MikeB]

On the main screen, press UP/DOWN until you get to the screen that shows 8 decimal numbers. These are the channel output values in percent. Find the number that changes when you move the control for the channel with which you have problems. Check it is 0 (or close to it) in the centre, and goes to +100.0 and -100.0 at the two ends.

Mike.

[Kilrah]

...and if it does go from -100 to +100 then the problem is either the servo ot the mechanics.
Remember that depending on how your linkage is done, even if centering is good the same amount of servo movement can result in a different amount of movement on the other end of the linkage.
So check the amount of rotation of the servo output shaft in both directions.

[MadScientist]

as stated a few post ago. the transmitter is sending a full -100/100 signal to the servos. everything except the channel i have limited to -80/80 is getting -100/100 out of the controller. I wonder if its something to do with my Tx/Rx. frsky acccst no telem pack

[jhsa]

Picture of your linkage with the servo centered please?

João

[MadScientist]

kinda hard to see without taking the plate off. Ill try to get to it sometime tonight. but here is enough so you can see how its put together.

ttp://s519.photobucket.com/user/565Customz/media/IMG_20130508_204055_996_zps6151eb16.jpg.html][/URL]

[MadScientist]

[gohsthb]

Have you tried plugging a different servo in to the channel and seeing if that works as you expect? If your limits are +100/-100 subtrim = 0 and no trim, then you have pulses going to the servo that command equal movement. It could be a bad servo.
-Gohst

[ShowMaster]

Have you tried a different radio system altogether? That or another servo on a "Y" cable with this one to see of they track differently being driven from the same RX channel?
The idea everyone is suggesting is to change around things to see where the error is actually coming from.
Of course a scope on the ppm tx out, or servo in would show you what the servo is seeing. There are free scope programs for a computer.
Not having a scope, substitution of the radio system or another servo, or another servo on a Y cable needs to be done to break up the closed loop system of parts your in now.
SM



Sent from my iPod touch using Tapatalk.

[MadScientist]

i have another identical servo I am going to try this week end. I dont know anyone that does rc around here, that would have the plug in module for the 9xr. if the servo doesnt fix it, ill try to band aid it with the limits.

[jhsa]

connect the servo to the receiver (same channel) but don't install it in the car.. judt check if the servo has the same amount of travel in both directions..

[ShowMaster]

Better yet, put them both on a y cable on the same channel and compare one loaded and the other unloaded to see if it's maybe binding linkage. Trying the servo in another spring return to neutral channel should be a first thing done.
I can't believe all channels are wrong. Servo or RC system? You've got to break this circle!
SM


Sent from my iPod touch using Tapatalk.