Strange servo


Previously i have tested my Arduino with a TowerPro Micro 9g servo. it is a general servo, worked fine.

Now i had to use it in a project, (RC car steering :wink: ) but it behaves very strange. When i connect to the Arduino without setting the servo up, it does nothing.
But when i connect to a pin, which is set up to a Servo library, it suddenly starts to screw to one end position, which wants to step over, and ignores the commands coming from the Arduino.

What can cause this? I haven't touched the servo for months, after the first test.
Other question, which servo library is suitable for this servo? May i trying wrong one?

Any help will be appreciated :slight_smile:

Did you remember a separate power supply and a common ground connection?

Of course! :slight_smile: As my earlier test with the servo.

OK, just needed to check.

which servo library is suitable for this servo?

I use the supplied Servo library almost exclusively.

OK, so that's not the root of the problem. Can be the servo faulty (but why)?
I have tried the supplied Servo Examples, Knob and Sweep, but exactly the same behavior from the servo...

I'd double-check that ground connection.
Or post a schematic.
Or both.

OK! I will review the ground wire&connector.
Schematic : imagine as there is a PSU which powers the servo, a servo got the signal from the Arduino, and the PSU and the Arduino is grounded together :slight_smile:

Have you another servo that you can try? They are not expensive and it's always useful to have a spare.

Can you try the problem servo with the code that you used when it worked?


I haven't. I haven't ordered more until i don't see that i need them - now i had to order a spare/replacement one, and as if i will use more servos, i will keep some spares :smiley:
Worst case is that i'll wait until the next servo arrives, and try to test again :slight_smile:
Thanks all all helping :slight_smile:

Try testing the servo out of the car. Make sure that the power is not connected the wrong way around.

I have taken out the servo yesterday as i realized that it screws only to one direction as soon as it gets control signal... I tested the power connection with direct power and ground from the psu to the servo, but exactly the same issue.
May be the servo is bad, but i cannot find out why :S
(I have taken apart th servo - not difficult, 4 screws - i cannot find any failures.)

I have tried the MegaServo library, but no success :S

Sounds like the potentiomer inside the Servo is broken. A problem seen a lot on the cheap small servos.

// Per.