Asked — Edited

Odd Servo Failure

Hi guys. I'm looking for some ideas on what could have happened here. I know there are several servo experts around here and I'm hoping I can get a little welcomed feedback. Richard R. You always seem to have good solid knowledge with servos. I'd welcome your comments if willing.

I had a servo burn up a couple days ago. It's not an EZ Robot servo but a Hitec HS-85MG servo being controlled through ARC. I'm not powering it through the EZB. It's being powered directly (past the EZB) from a 12vdc to 6vdc converter. I have one other servo sharing this power converter and it's also controlled through ARC.

Here's what was going on when the HS-85MG overheated and smoked; I had not yet initialized or sent any signal to the soon to be smoked HS-85MG through ARC however it was powered up from the converter. I had the other servo sharing this converter holding a position set from ARC. I had a third servo moving up and down using a servo control slider in ARC. This third servo is powered by a different step down converter (at 7vdc) and also bypassed around the EZB. Both the step down converters that powers these three servos share the same 12vdc feed.

As I moved the third servo powered by a different converter, the HS-85MG that was not yet initialized or had a movement command sent overheated, started smoking and was destroyed.

I can't figure out why if the HS-85MG had not yet been started (but powered up from a shared converter) would lock up and burn when a separate servo was moving.

I've noticed at other times with other servos, if I haven't initialized and then released them in the INT script, sometimes they tend to twitch when other servos move. However I've never had any of them lock up and burn like this.

Any ideas on what could have happened here and how to avoid this in the future are very welcomed. confused


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Twitch is because the servo signal wire is picking up static in the air. The input signal of the servo is floating.

Electrical components can pop for their own reason. All servos will smoke or burn out when the mosfet gets too hot or wears out from excessive heat over time.

Have you checked and verified the voltage to the servos? Double check.


Hitec HS85-MG servo is rated at 4.8 to 6vdc. I think 7volts could be you problem cause.


Sorry for being unclear. I was feeding 6vdc to the HS85-MG. I've tested and confirmed that I have this voltage.

It was the third servo that I was moving when the HS85-MG burnt out that was being feed by a different converter feeding it 7vdc .

Thanks for the suggestion though.