AC Axis Drive Adjustments

Replacing A Servo Drive

1. Power off the VMC.
2. Lock out/tag out the machine.
3. Remove the orange connector or disconnect signal wires on the front of the faulty card.
4. Disconnect the power and motor wires.
5. 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.
6. Replace the amplifier.
7. Reconnect the orange connector or signal wires on the front of the new card making sure that they are installed on the correct terminals.
8. Connect the Power and Motor wires, insure their correct position.
9. 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.

AC Axis Drive Systems

Adjusting the amplifiers with the axis cards is done by using the red Light
Emitting Diodes (LEDs) while adjusting the potentiometers. In order to use this
method, the axis cards must have software version AC0003-5 or higher.

Balance

1. Press the MANUAL button until the ENTER NEXT COMMAND screen is displayed.
2. Type DI and press the ENTER button. Type DL, and press the ENTER button. This will display the percentage of load, instead of the axis following error, in 1% increments. This command prepares the axis card for balancing the amplifiers.
3. Press the MANUAL button to return to the ENTER NEXT COMMAND mode. Observe the red LED on the axis card. If the light is on or is blinking, the amplifier is not properly balanced.
4. Turn the Balance potentiometer, on the amplifier, until the LED goes out. The slower the light blinks, the closer the amp is to the balance point. If the LED starts blinking faster, the potentiometer is being turned the wrong way.

Signal Gain

1. After the balance has been adjusted, the Signal Gain must be adjusted. Change the program that was entered on the previous page to read as follows:
   • N2 M91 M49 G91 F25.
   • N3 X-2.Y-2.Z-2. G1
   • N4 X2.Y2.Z2.
2. Start the program. With the program running, observe the red LED on the axis card The red LED should not be on. When the axis changes direction the LED will come on for a brief interval and go out until the next change of direction. Adjust the Signal Gain on the axis amplifier, until the light goes out. If the light goes out in one direction, but not the other, the balance will have to be adjusted again.
3. Perform the Balance and Signal Gain adjustments on the remaining axes. If the desired feed rate for adjustment purposes is 25 ipm (F25), mm pitch ballscrews will have a following error of 50 and Inch pitch ballscrews will have a following error of 100. Rotary tables will always have a 2000ipm feed rate for 90:1 ratios and 1000ipm for 180:1 ratio and a 680 following error. If the VMC is being adjusted for rotary dies, using a feed rate of 150 ipm, the following error for the X,Y, and Z axes is 465. The following error for 25 ipm is 78. The A and B axis still use a 2000 ipm feed rate. The following error is 540.

Troubleshooting AC Axis Drives

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