Replacing MKS Gen 2Z board with Ramps 1.4 - Z Axis Motors Not Moving Properly

Hello,

I got a sunhokey prusa i3 printer which uses MKS Gen V1.1 board, but the board burned due to a defect in the supplied PSU. At first I didn't know it was the PSU, so I decided to replace the board with the original ramps 1.4.
The MKS Gen board is supposed to be a derivative of ramps with mostly the connectors changed, however I ran into the following problem:

All the motors work ok, except for the two Z axis motors. On MKS gen board there are separate drivers for each Z axis, however on ramps there's 1 driver for both.
And the motors occasionally stop and start moving - it's not the expected smooth movement. Looks like it's just not enough power. If I tune the pot on the driver to give them more power - they start working fine, but then the driver heats up too much. If even heats too much if the power is still not enough to move the 2 motors smoothly.

And I'm wondering - is it just that the driver is too weak to drive those 2 motors or is it something else? I had to cut the motor connectors and crimp them into new connectors that fit the ramps board, and although the connectors seem ok, I'm wondering if my crimping could be the problem (since it's the first time I do that ).
The two motors are given as 1.5A each (can't see a model number), while the ramps driver says it's rated at 1A continuous and 2A peak - does it mean it's supposed to work with smaller motors?

Could it be a problem that I'm using the Configuration.h that ships with the MKS board? Is it possible to reconfigure the Marlin firmware to use two drivers for the Z axis - since the second extruder driver is free now?

Thanks in advance for any clues!

Edited 1 time(s). Last edit at 09/16/2015 04:31PM by ltomov.

Hi,

Generaly people change Ramps for MKS gen or better.
MKS Gen (actualy 1.3) is a better board than the 1.4 Ramps.
You're going counterclockwise

Anyway, for your Z motors, it's probably a wiring issue.
Dupont connectors are known for contact failures.
You probably don't need a lot of power for your driver,
even to operate two motors.
If your motors are rated 1.5A you should set
the output voltage at 0.6v for allegro 4988
and 1.2v for drv8825.
Check it out with a multimeter.

If you used 2 drivers for the Z axis on the MKS gen,
you just want configurate your existing Marlin configuration and bybass Z2.

++JM

Thank you very much, that solves it.