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Reset Calibration


I have been trying to figure out how to reset a servo's default 90, my robot head turns almost 180 degrees to the right and 5 degrees to the left.

I tried the screw, and re aligning but its clear the motor thinks its at 90 when its closer to 180. how do you reconfigure a servo's set 90 position?


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So it's one servo we're talking about? If so can you just add a basic vertical or horizontal servo control to your project and see if it at least responds correctly various positions commands?.... If a servo is not positioning properly (even after you have calibrated it and fine tuned it) then it is most like a faulty pot... In which case there is no way to as you say... to reset it....

United Kingdom

Revisit the Calibration Lesson

The servos position is taken from the servo, if it thinks it's at 180 it is at 180. The only way this would not be the case is if the servo itself is damaged and the internal pot is no longer being moved by the servo. Replace the servo.

If you do not want to replace the servo for whatever reason repair of the servo may be possible however I would still recommend replacing the servo as, by asking the question it is clear you are not knowledgeable enough to repair the servo - it's not an easy task.


Remember, the servo always knows what position it is in. The calibration process is moving the bracket to match the servos position.

For example, you set the servo to 90. That moves the servo to what it knows as 90. If the bracket does not match up to 90, then you have to calibrate the bracket.

Maybe the lessons should be called calibrating brackets:)



is it possible that a servo doesn callibrate good? and how can you see that.


@nomad... if the servo has difficulty positioning then it is defective... For example if you tell the servo to move to 90 but the servo has trouble holding 90 (it chatters) or moving to another random position instead then the internal pot is defective...


yes, in my case when calibrated correctly and i try to turn the head to his left i can only go from 90 to 100 which brings the head about 6 positions to the left but he cant look the the far left only a few degrees past 90. If i try to go right his head will spin around almost backward so he can see what is behind him.

Out of curiosity i figured offset the calibration to see where the real problem is so i hooked up his head to be positioned off the the right so that hopefully it would allow me to let the head turn further to the left by using the calibration tool in windows to say -22 so his head was straight but instead when it got to the point it would normally stop at it started jamming saying it was past its max and i stooped it.

is the head meant to turn further in one direction then the other?


It doesn't sound like you are calibrating corredtly. When the servos are set to 90, they will move to 90. If the object connected to the servo is not at 90, you will need to detach and reattach the object to be at he 90 as well.

You are in Calgary, are you not? Maybe drop by the office and we can help you. I'll be around tomorrow day. Or I can meet you tonight after my plane lands from Seattle after 7 pm


Im in Cambridge, Ontario, and i have tried to calibrate it several times to be sure. i did it by detaching the horizontal head clip and running the "all to 90" in the diagnostics and then attaching it to be sure it was on correct. this is the 3ed robot i have built so i have tried all the normal stuff i should try


Oh! I thought you lived in cKgary for some strange reason that only my crazy spaced brAin can justify. The other revolution robots you built calibrated the attachments correctly?

So it's just this one? That seems to change its 90 degree position?


yep the ones i calibrated and configured for hobby and toy central where fine, its only this new one i got for myself thats an issue


Interesting! I wonder if the pot inside is loose. Feeling adventurous to open it up?

The little potentiometer inside reports the position. There is usually a screw holding it in place.