Burned right hand motors

Hello to everyone and it´s a pleasure to be here.

Another noob is here, from Brazil (but only speaking German and English).

I have started 2 weeks ago printing and assembling the right hand of the amazing Inmoov project (BIG thanks to Gael). Everything was ok so far, was able to run simple scripts with Arduino. Since 2 days I am working MRL and here the problems started (using Inmoov2). Wanted the hand to listen to me and do simple things like rest, open hand, close hand. But if I say "open hand" he is listening, understanding and I even can read that MRL is changing the servo position, but suddenly the servos did not move but burned after a while (using MG946R and MG995R). As mentioned before I have tried several Arduino scripts like Servo90 changing to every correct position. At MRL I was able to attach and slide every single finger (servo)  from 0 to 180 degrees, moving just perfekt.

As all hardware is hard to get here in Brazil (at least for a normal price!) I will get 6 MG996R these days (was reading Gael´s post) hoping they will do the job. Nothing else to get here at the moment and I am not going to spend R$ 600,00 ore more for one good servo.

Thanks in advance for any help and all the best from Rio de Janeiro!



wvantoorn's picture

You had to tweak them and

You had to tweak them and adjust the minimum and maximum, your servos you used are known to smoke when too long and too much work has to be done.

when you turn a servo manually in mrl you hear him buzzing at start and maximum. And then you need to push the slider a bit back to make him stop wanting to move. When moving there is the most current going through the servos and therefore magic smoke!

i am setting my head and neck servos tomorrow, is the same for other servos, and make a tutorial for it.



Mastablasta's picture

waiting for new servos

Thanks a lot.

I should receive the 996 servos by the end of the week and I will do exactly what you have said.

If I understand this right I could set (just for example, to avoid any max or min) set the min to 30 degrees and the max to 80 degrees. This way it should never reach any limit but I could try open and close hand, sure the hand will be closed at 80 and open at 30 degrees at this moment. Just for do some testing.

I am already printing the biceps parts but I want to catch up with MRL and the programming. No need for a dead robot!


GroG's picture

First a moment of silence for

First a moment of silence for your dead servo _______silence___________
We have all experienced such loss.. and give our condolences.

Now please let us know what scripts you were using at the time..  I'd like to put some default Min Max values in, so that the death of your servo is not in vain .. and future MRL'ians can be in a better safer world...

Also, you might want to ask dwilli about his deadman switch .. its very handy and has probably saved many servo lives...  (he should do a tutorial)

Last thing - change your avatar .. you are no longer scared gopher !!! ..  Welcom Mastablasta

Mastablasta's picture

Hello GroG.Thanks for your

Hello GroG.

Thanks for your sympathy :-)

I have used the minimal.py and the full.py. At the full.py I have disabled the left side/head/neck etc. Was talking and understanding more or less ok (need to get a better microphone) and I could see at the script the servos received their order, but they didn´t move too good. I guess at this time it was already too late, burned.

I will change the max/min in the script and at the slider next time.

Anyway I need to run new braided lines. This way I can try the servos without the load. I was forced to use 0,30mm braided line as nothing else was available. So I fourfold them, 8 lines per finger, what a painful work! Now finally I was able to order 0,85mm braided line.

As mentioned before, I have started 4 weeks ago with a DIY 3d printer kit and this project, never worked with Arduino or MRL. But it´s a challenge for me and I enjoy a lot.

Different question: Would it be possible to run a Gimbal Brushless Motor with MRL? I don´t want to make a gimbal, just to get one or two motors running (like a stepper).

Avatar has been changed!


GroG's picture

Motor control typically is

Motor control typically is pretty easy.

But you need some electronics to move a motor (H-Bridge or other MotorController) .. so I would need details on the Motor Control for me to answer you.

Nice Avatar .. thanks .. I've seen too many scared gophers...

Mastablasta's picture

Thanks. This is a very early

Thanks. This is a very early drawing of C3PO I know since 1977. Still a beauty to me.

Can I use a Martinez-board? I use it for the gimbal on my multirotor and I am able to control 2 motors with my radio without the accelerometer module. Would be great to be able to control these signals with MRL.

Mastablasta's picture

new servos

I will get the mg996r servos today and I would like to run the InMoov2.hands.py script for testing the wrist and the 5 fingers. Can I set the value e.g. to 20 degrees min. and 120 degrees max. just to avoid any burned servos again? Just to test to voice commands, later I would need to adjust the settings of course so the fingers have the right position.

Thanks for any help.

wvantoorn's picture

To test the servo, put the

To test the servo, put the tendons on, and open mrl with a slider, and go from 0 to max. When on max or where you want, if the servo humms loud, go 1 step at a time back until the servo goes silent. That is your max. Same for min.

Mastablasta's picture


Thanks for the help. I will start the surgery soon and keep you up to date. I am using a mg995 for the wrist. Looks like that one didn´t burn. Only will replace the 5 fingers first with the mg996r.

Mastablasta's picture

No respnse

New problem.

I have changed the servos and now MRL won´t work anymore. Looks like MRL does not get the arduino anymore. Error message Python: "No line matching interface TargetDataLine is supported".

At Arduino everything looks to be fine, was testing 2 servos and all ok.

Accepting any help.

GroG's picture

It looks like your current

It looks like your current audio output selection does not support sending sound through it.

Without a no-worky we are blind....

but my first guess mabye is to reboot ?  What has changed since when it did work ?

This is a "sound" complaint error - so I don't know why there would be issues regarding the Arduino ports.

Mastablasta's picture


The power source can be the only problem. I have used a 6v bec before, its light isn´t as blue as before and it is getting very hot very fast. I told you I will change my name soon to mastaburna! Sure the bec did not have enough amps fore all the servos. I have already ordered a 6v 12ah battery to be on the safe side. I have 30 power-supplies here but no 6v for the servos.

Nothing else has changed since then. I can run one servo with the example at arduino, as soon as I use a second servo all things stop/go crazy. Reboot has been done. Nothing else I can do until I get right power supply.

Waiting for the sun.....


GroG's picture

I don't do batteries.. I use

I don't do batteries.. I use thrown away ATX power supply.. This is power supply unit from a broken desktop computer. Can you find these things?

Mastablasta's picture

power source

Thanks Grog. Since yesterday I am thinking what to use as I need to order a battery and I would like to make some progress this weekend. An ATX power supply would be available, I could get one today. This means I need to run the servos on 5V as it only has 3,5v 5v and 12v output.

Really have learned a lot here these days here at the forum. Thanks to everyone.

Mastablasta's picture

Power Source


Managed to get an old ATX running, hoping 5,25v will do the job.

Mastablasta's picture

First video right hand

Finally the first success!