[Lasr Da Vinci]

I've had a Hobbycnc EZ board for almost a year, which during this period it was working fine until a couple of weeks ago when the X axis motor stopped working. I checked all the connections and they seemed fine. I checked the screw terminal voltage and for the Y axis it was 0 volt. I concluded that the Y chip was gone.

I ordered another chip from HobbyCNC, I replaced it and it worked fine for about 3 minutes, and then it died again. No smoke, no popping sound, no sign whatsoever.

I have a decent size heatsink with a fan mounted on all 3 chips. the heatsink has a thermocouple connected to a digital temp. gauge, so I rule out heat as the culprit, and the fact that It worked fine for almost a year and then it suddenly stopped working baffles me. X and Z axis are working fine.

I read some threads of HobbyCNC board users with the same problem, but I found no concrete reason for this failure. Any ideas?

Thanks,

Gustavo

[ger21]

Thoroughly check the wiring to the motor.

[H500]

Any chance that your motor has shorted out?

[neilw20]

Any loose motor wires, or internal connections in the motor will cause havoc.
Because the motor is inductive, any intermittent connection to or within a winding can generate very high voltages, ... read that as 100s or even 1000s of volts, if the connection is interrupted when the current is above quite a low value.
Intermittent shorted turns (in a winding) can create similar problems, especially if the shorted turn gets hot then causes a disconnection that generates a spike.
Shorts may exceed the ratings on the driver also.

In all probability it is the motor or the wiring, but the problem could be IN/ON the pcb.

Look for loose connections.

If it worked for three minutes, then just replacing the chip won't fix it for longer than 3 minutes if the original cause is not remedied.

[Lasr Da Vinci]

I've checked all the connections but I did not find anything unusual, but I did discover this: The voltage on X and Z screw terminals is normal (I believe it was 2.8V?) on both Aa and Bb. The voltage on Y axis terminal without the motor connected was >12V! With the motor connected was 0V. I am not electronics savvy, I know how to use a meter and check components, but I wouldn't know the first thing about figuring out what component is gone bad. Any suggestions?

[neilw20]

Those numbers look normal. 12v disconnected, is not unexpected.
You really need an oscilloscope to make much sense of the signals.
Take a whole heap of pictures and we might be able to figure out more.
Details of wiring, connectors and cables.
Flexing cables that move, or soldered joints on moving wiring is important.
Any soldered wires that do not have 100% support at the solder joint WILL FAIL if there is repeated movement.

[Lasr Da Vinci]

Problem solved.
As usual, I tend to complicate things more than what they actually are. I went over all the wire connections again, and one of the stepper wires came undone. I could not see it because it was covered by a piece of shink tubing.
Thanks, everyone, for taking the time to help me.

Gustavo