[skipper_52]

I'm using Mach 3 with a 4 axis Gecko drive. When I use the keyboard to jog the machine on the Z azis only it will reverse itself (pg up sends carriage down and visa versa). It is not consistent. If you tap the keys it will reverse itself again. I've reinstalled Mach 3 and changed the keyboard with no help.
I'm praying it's not the Gecko drive. It does not happen on the X and Y axis.
Thanks in advance.

[ger21]

Try increasing the pulse widths in the motor tuning to around 10. If that doesn't help, you may have a weak parallel port.

[skipper_52]

Try increasing the pulse widths in the motor tuning to around 10. If that doesn't help, you may have a weak parallel port.

Found the problem. swapped the y and z cables and y acted up, z was ok. That told me it was in the z cable. Opened it up and 2 wires were lose from the solder joints. Works fine now. Thanks for the help.

[MINGMEICNC]

swap cables as you did for example sometimes can easily solve your problem. You swap the cables Y and Z, if same problem happened on Y it meas your cable or driver has something wrong .