Trouble with z-axis motors  

Trouble with z-axis motors

Hi

I am having trouble with calibration. I have adjusted the belt tension on the x-axis
and y-axis motors. They seem to be OK. The z-axis has a problem. It seems like only one
motor is turning and the other one seems not to be powered.

More specifically the symptoms are:

I can get through the calibration step to find the four corners,
although it ends in failure. To get this to run I must manually
position the X-carriage to the very top.

If the carriage is at the bottom. the calibration process stops
immediately.

One of the z-axis motors seems to work and the other seems to be
completely idle and free wheeling.

While powered up the z-axis motor that works is hard to manually turn,
while the other motor is able to turn freely (and it may not hold the
weight of the X-carriage).

Using the settings:change axis: change z, I can easily lower the
X-carriage, but I cannot raise it (The one side raises until the
carriage binds.)

If I swap z-axis cables on the EINSY motherboard, the motor that works
and the motor that doesn't work swap sides. This tells me that the motors
both work and the cables both work and the problem must be in the EINSY motherboard.

On manual inspection both connector have 4 pins on the motherboard.

I suspect an EINSY motherboard problem.

Do you have any suggestions for me to try?

Thanks in advance

Kirk