GT2560 w/4988 driver boards

[rotormansa]

I'm really quite new to the printer and 3D printing, but I am an Electrical Engineer the technical aspects of this machine isn't beyond my capabilities.

I purchased the Geeetech I3 Pro B and after a bit of an issue trying to locate the correct assembly instructions, the machine is built. The machine as a few issues and I'll go into one of the more annoying problems on this post (look for additional posts in other areas of this forum group.

During the assembly and before finally button up of the unit, I tested the stepper motor functionality. The Y-Axis worked great as did the X-Axis, although the direction seemed reversed; the auto home feature was sending the carriage away from the limit switch. The Z motors were an issue; both were humming and buzzing and one would not spin at all and the other was having difficulty spinning (from the sounds it was making. I removed the stepper motors from the mounting and let them operate in free space and not connected to the threaded rod (thinking there was some binding). The same result occurred in free space. After a bit of debugging I realized that the attached cables provided with the stepper motors had three identical cable and the one motor that wasn't turning had a cable that was not wired like the other three. I made this odd cable look like the others and tried the test again, still no luck the motor wouldn't turn and the other motor was still buzzing and not turning so good. I then thought perhaps it's the GT2560 or the A4988 driver board. I swapped out the working X-Axis A4988 driver board with the Z-Axis driver board and tried my test again. The Z-Axis (both) were spinning well but the X-Axis motor was now dead. The conclusion is the kit shipped with a bad A4988 board (I am awaiting a replacement from Geeetech).

I made certain the aluminum heatsink wasn't touching any of the contacts on the carrier card for the driver and all looked fine. So I can only conclude it is a bad chip. I visually inspected the suspect board and didn't find any oddities.

Annoying out of the box experience.... now I have to wait for Geeetech to ship me a replacement driver. What's more bothersome is the e-bay seller told me I had to make a video showing the issue (which I did) but for a $2 part??? Just really bad customer service on the sellers part and Geeetech.

RotormanSA

RotormanSA

[bang]

A video to show the driver issue...