I recently purchased two identical 600 oz/in DC servo Motors from Keling. [I had ourchased many items from them in the past and always found them to be responsive, ship promptly, etc.]
After using one of the motors for a few hours, shutting down the system the Gecko drive belched black smoke sizzled and I went for the power switch. replacing the Gecko produced the exact same results again.
I then checked voltages supplied from the power supply and the BOB and found everything in order. I checked all wires and cleaned up things pretty well and proceeded to fry a third Gecko. I guess I'm a slow leaner.
Checking the motor itself revealed the resistance betwwen ground (green) and positive (red) to be 0.8 ohms. The resistance between ground (green) and common (black) was also 0.8 ohms.
The other identical motor supplied (and all other motors in my shop) have infinite resistance between ground and the power leads.
I don't want to malign anyone, I still need to be more parts, but this seems to be a motor problem to me.
Any thoughts other causes?