Replacing A Servo Drive

Power off the VMC.
Lock out/tag out the machine.
Remove the orange connector or disconnect signal wires on the front of the faulty card.
Disconnect the power and motor wires.
Using a long phillips screw driver, loosen the two screws securing the amplifier to the chassis. Slide the amp. to the other side and remove.
Replace the amplifier.
Reconnect the orange connector or signal wires on the front of the new card making sure that they are installed on the correct terminals.
Connect the Power and Motor wires, insure their correct position.
Turn the Loop Gain and Current Limit potentiometers fully clockwise.
- A axis amplifier slot #1 (far left when installed)
- X axis amplifier slot #2
- Y axis amplifier slot #3
- Z axis amplifier slot #4

After replacing one or more of the servo amplifiers or if an axis motor has been
replaced, you must adjust the position loop gain.

DC Axis Drive Systems

Note: Set the master feedrate clock before beginning this procedure. The Position
Loop Gain and Master Feedrate Clock are interrelated.

Enter the following program:
- a. X-4. Y-4. Z-4. G1 F150. M49,M91.
- b. X4.Y4.Z4.
- c. M99P1
Press Auto, to start the program running.
At the amplifier to be adjusted, Use a small screwdriver and turn the SIG2 potentiometer until the monitor’s display of the appropriate axis reads the following error: 595 – inch ballscrew / 302 – metric ballscrew.
Press the SLIDE HOLD button on the keypad and adjust the balance of the amplifier to read between 0 – 1.
Press the START button on the keypad and the program will start again. Verify that the following error is still 595 or 302.
Press the SLIDE HOLD key to stop the machine. Press the MANUAL key and then type SETCS and HO, to send the machine home. Adjustment of the amplifier is complete. Repeat the procedure for all axes.

If errors occur or an axis is inoperative, go to Section 16 of the maintenance
manual. Flow chart number 4 is for axis control problems.