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Asked — Edited

Servo Burning Out

I was showing my wife for the first time how to position Six. and as we were working on it. I smelled that electrical smell you get what things are not going right. looked down and the servo was glowing. I cut the power by the switch under him but there is melting damage. I have had my six since. What is the length of time one can ask for a defective part replacement?

Unfortunately the servo must have been prevented from moving for it to catch fire or glow. Unfortunately , that would not be a warranty replacement. Check the cables to ensure one was not wrapped around a clip or bracket before using. Also proper servo calibration will help if the brackets haven't been calibrated. We have only burnt servos in our tests intentionally. I still have my six and JD with servos from August 2014 :)
Thank you DJ,

It was holding up the weight of The Six as we were working out a walk pattern.
There were other servos holding Six up as well so the weight should have been distributed some so the one servo was not holding up the complete weight.

I have had the bot for some time so I was sure there would not be warranty on the item.

I have some 200+ servos and have had them fail before , I had never had one burst in flames. hahah
On and off subject DJ.

I had a birthday the other day and my family wanted to get me some store credit here at EZ-Robot. They could find no way to buy a gift card or credit for my account.

This could be a nice thing to have. as I have had community members I have helped and refused to take money from. I would take store credit.:)
I've had a few servos burn up. Mostly because of just a few things; Trying to lift too much weight, holding too much weight for too long or getting hung up on something mid move and not seeing it till I smell the smoke. All my fault. *tired*

Happy Birthday Luis!;)
Roli seems to have this problem
The shoulder servo has to hold the weight of the arm all the time.
Mine caught on fire the 3rd time we used it.
Mac75, was there an actual flame? The servos are designed to burn out - not catch on fire. If there was an actual fire, please expand on your experience.

Also, a while ago the roli project was updated to put roli in a position to relieve the weight holding the arm. Ensure you have the latest roli project and latest ARC software installed.

If the roli servos are not calibrated, that may also cause issues. There is information in the learn section for roli which will be able to assist if you continue to experience troubles.

As ezrobot has never burned a servo on roli, jd or six - we do come across customers who have experienced burn outs. Burn outs is how the servo was designed to prevent fire. The burn out acts like a fuse. It will heat and release a black smoke, perhaps the heat melting the plastic surrounding the area. This design burns out one of the two transistors which powers the motor's direction. The transistors are designed to be the first to "pop" in case of over exertion.
I extended the length of my RoLi arm with several additional servos so that it has more reach and ability to do actual work. I did set a couple of different auto-position "resting" positions to relieve the stress of holding all that weight with the arm fully extended, but more to quiet down the buzzing than to prevent burnouts. I have never had a RoLi servo burn out even when leaving it straight out with all the weight on the shoulder servo.

As DJ said, I would check your calibration and make sure you aren't trying to move into an impossible position and that all of your wires have freedom of movement in every servo position so you aren't adding additional stress to your servos.

Hey DJ,
You are right about "no flames". The plastic containing the servo was melting, and the term burning out is more accurate than on fire.

We have always had an issue with the Roli shoulder servo buzzing and can attest to making different resting positions to alleviate this problem also. I have worked with dozens of students calibrating servos and we look at the wires as part of our daily start inspection.

So if the servos were correctly calibrated and the wires were not adding additional strain could there be another explanation?
Mac, James had sent me a message regarding your conversation - everything is being taken care of:) glad to hear there were no flames. The smoke may be misleading - however, that's the result of any circuit protection:)

I do a lot of work with robots and general R/C stuff and I burn servos sometimes.
Sometimes servos fail because of damage to the internal gears. this can happen if you to much force on the servo. Even if the servo is powerless you can damage the gears inside if you move the arm suddenly with to much force. If you strip a gear sometimes the servomotor will run without moving the arm. But sometimes parts of the gears block the transmisson and the servo burns out for no reason. For me this sometimes happens in my R/C planes where a bad landing can stress the servos.

To prevent overload in my robots i make a small board with fuses for servopower. Then i measure the current in normal operation and picks a fuse as close to the value as possible. If a servo gets blocked or overloaded the fuse will cut Power Before the magic smoke appears.
Fuses are the bomb! Best thing that ever happened for protection since the trojans invented the concept. To save in fuse cost and make it more user friendly they do make resettable fuses of all sizes. Kinda like little snap in circuit breakers. Very cool and less flustrating. *eek*

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