I'm working on a device that controls three stepper motor actuators, one servo motor and a DC motor/encoder. The stepper motors and DC motor are run at 6V and are controlled by an Arduino Nano's GPIO pins, connected to four L293D half-bridge motor drivers.
In the above schematic, U6 is connected to the DC motor. U5 and U4 both control stepper motors and share GPIO connects as they are expected to operate in sync on an axis. U3 also controls a stepper motor, but on another axis.
I've been running into a problem where one particular L293D (U3) overheats and burns out, forcing me to replace it. The other L293Ds do feel warm when I'm testing (possibly uncomfortably so, I haven't burned myself yet), but it doesn't feel like they're getting nearly as hot as U3 does.
I'm considering replacing the L293D with a different motor driver, but I don't want to make such a big change without determining as best I can why U3 in particular keeps overheating like this. I'm still gathering information, but if anyone sees something already, I'd be glad to hear it.
Update: Okay, I've been able to do some more testing, and it seems that U4 &5 are also getting hotter than I expected. I'm still pretty sure that U3 is getting hotter at a more rapid pace than U4 & U5, but its still all uncomfortable temperatures that could burn if left alone. I still don't know why U3 is the one that keeps actually breaking, but I think it's fair to say that all three L293Ds connected to the steppers are at least in danger of burning out. That said, this doesn't seem to be common to all the boards I'm working with. I'm working on getting some proper current measurements to go with this.
