Drifting Stage, Drifting Joystick - Troubleshoot and Fix

Symptom

When the software is started and nothing is apparently deflecting the joystick in any direction, the stage is moving continuously. This movement can be slow enough that is an't be seen when looking at the stage itself. The movement of the stage might be visible in the live camera view or in the numerical values of the current X and/or Y coordinates or in the Stage Pattern window.

Possible Cause

This symptom could stem from deflecting the joystick repeatedly to it's maximum and then let it to spring back to its center position. It seems that the joystick can take it for a time but at some point, an adjustment is required.

Confirming the Problem

To confirm your joystick has this problem, you need to disconnect the joystick from the Tango PCI card in your computer or from the Tango USB controller. Then, when you start the software, there should not be any drifting and you should be able to use the Virtual Joystick to move the stage. 

The virtual joystick is accessible from the Stage Pattern window:

The stage should not move by itself unless you are using the virtual joystick.

Use the virtual joystick to go (approximately) to the center of the stage.

If the stage is moving regardless if the joystick is connected, let us know, we will investigate further.

If the application is started and the stage is behaving normally with the virtual joystick, proceed with the following instructions to fix the issue.

Fixing the issue

With the joystick disconnected, remove the 6 screws underneath the joystick:

The following picture shows where the tuning for both the X and Y axis are located:

When you adjust the trim potentiometers (marked X and Y adjustments on the picture) you should feel a little bump at the center position. When you make these adjustments, make sure the joystick is not deflected in any direction. Holding down the joystick mechanism (marked Hold Down on the picture) during adjustment helps stabilizing the whole assembly. 

 Now close the software, and re-connect the joystick. 
Keep the joystick open and the adjustments accessible. You can now open the software and adjust the drifting axis to the point where the stage stops moving. The X and Y positions must be fixed in the virtual joystick window when the joystick is at rest:

 

When you reach stables values for X and Y positions, you can screw the joystick back plate in place and you should be good to go.

Let us know how it went.