Welcome to the SeeMeCNC Community

I have built a h-1.1. In testing things out, the motor on the z-axis seizes up when I use the software(Repetier) to tell it to go either up or down. It also will not turn at all and appears to be locked up when the RAMBO is powered up.

I though it was the motor or the mount, but when I plug the z axis axis motor into either the x or y sockets, the motor works fine. Any motor plugged into the z socket behaves the same. Is there something in the firmware I need to adjust? I have tried both Marlin and Repetier firmware.

It sounds like you are over driving the stepper. Firstly, when you power up, all of your steppers should feel like they lock up - that's their holding force.

As for the Z, try lowering the Z feedrate to 75mm/min or something like that. You can also test this manually in Pronterface by changing the z_feedrate in Settings and then test moving the Z up and down. Or in Repetier, edit the printer settings and change the Z axis travel feedrate on the Behavior tab.

Give this a try and report back.

cheers,
Michael

Tried that, it did not work. Redownloaded the Marlin firmware to the board and it work fne. I thne tried the Repetier firmware again and still no luck. Also tried changing the Zaxis feedrate. FYI I used the Repetier for Rambo firmware.

Unless it's been fixed in that branch Repetier had bad pin mappings for RAMBO, both the max end stop pins and the bed heater pin were defined incorrectly.

Can it be fixed by modifying the configuration.h file?