Z motor possibly going south?

I noticed that my Z motor is running substantially hotter than any of the others. I shot it with the infrared thermometer and it’s showing 125-130 deg. while my X and Y’s are all about 84. Running a 24v power supply generally keeps things running cooler (I’m running an aftermarket controller). But my Z must have been running hot for awhile because it destroyed the small molex connector end of the Z cable and I had to rewire it. Seems to be working well, other than running hot.

I know the Z axis gets quite a workout, but this measurement was taken while running a job with very low Z demand, and after a few minutes when the job was done, it was still hot @ holding torque.

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Hey Bill… Check your holding torque settings. You should be able to get away with .5amps with a standard setup.


Good call Mark. The G540 automatically handles holding torque (i.e. not explicitly user adjustable), but it did prompt me to check my current limiting resistors in the DB9 backshell, and I found that I have a bad resistor in the Z axis DB9 connector. Will swap that out & report back.

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Could you post a photo?

John, you mean of the melted connector? Sorry, I didn’t happen to get a pic before I applied my sort-of temporary fix. It was the small end connector, the one that would normally plug into the 1F controller. Mine plugs into a short pigtail I made where one end is the molex connector, and the other end is a DB9 connector that plugs into my G540 driver.

Sorry I meant where the bad resistor was.

@TheyCallMeJohn It was in the Z axis DB9 on the back of my controller. Turns out it wasn’t a bad resistor at all, just a bad solder job (or complete lack of). I needed a 2.8k resistor on each connector. I ran out of 2.8k resistors, so I put 2 5.6k in parallel and botched the solder job and the result was seeing 5.6k. Now that it’s fixed, all is well and the Z axis motor is running the same temp as the others.


More info on this would be great.