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Swapping a Centroid SERVO1 Drive

This document applies to Centroid DC servo control systems using either the SERVO1 or QUADDRV DC drive units.

In the event of a servo drive failure, you will need to remove your servo drive and either replace it with an exchange unit, or send it in for repair and return.

Early drives (1993 - 1995) are mounted on a finned heat sink, with the cooling fins outside the right side of the cabinet.

Later drives (1996 - present) are mounted on a flat heat sink, entirely inside the cabinet.

Drives in post-1998 Revolution controls are mounted upside down on the left side of the cabinet, with the logic power supply mounted separately on the panel.

In all cases, the heat sink is part of the drive, and comes out with it. The procedure for removing and installing the drive varies depending on the type of heat sink.

Removing the Drive

  1. Make sure that all wires and cables are clearly labeled, so you can get them reconnected in the right order.
  2. Make note of the positions of the limit switch DIP switches and the drive fault DIP switches:
  3. Disconnect all wires and cables:
    1. Optical fibers "DATA" and "SYNC"
    2. Limit switch cable
    3. Drive fault cable
    4. Z axis brake wires, if present
    5. Motor power leads, RLY1/RLY2 wires, Motor bus wires
  4. Unplug the 120VAC connection to the logic power supply, in back of the drive. This will be a three-position in-line connector with a thumb latch. The wires will be black, white and green.
    If you have a post-1998 Revolution with the logic power supply mounted separately, then leave the logic power supply in place and just unplug the DC cable from the drive. It is the white Molex 6-position plug with four wires, between the drive status LEDs and the fault cable.
  5. Remove mounting screws securing heat sink to cabinet wall
  6. Remove the drive:

Installing the Drive

  1. If the new drive has a flat heat sink, and the original drive had a finned heat sink, then you will need to enlarge the holes in the cabinet to allow #10 screws to pass freely.
  2. Install the drive:
  3. Install mounting screws from outside the cabinet wall. Get all the screws started before fully tightening any of them.
  4. Plug in the 120VAC connection to the logic power supply, in back of drive
  5. Reconnect all wires and cables:
    1. Optical fibers "DATA" and "SYNC"
    2. Limit switch cable
    3. Drive fault cable
    4. Z axis brake wires, if present
    5. Motor power leads, RLY1/RLY2 wires, Motor bus wires
    Be especially careful of the VM bus polarity. The minus side (often labeled "GND", and usually a Blue/White striped wire) goes on terminal 9. The plus side (often labeled "VM" or "VM+", and usually a solid Blue wire) goes on terminal 10.
  6. Check the limit DIP switches and fault DIP switches, and set them to match the setup on your original drive. When Centroid ships out a replacement servo drive, they nearly always leave the DIP switches in the "test" position (necessary for bench-testing a drive before shipment). Therefore you will almost certainly have to change them back when you install the drive.

Testing the Drive

  1. Press in the Emergency Stop pushbutton
  2. Power up the control, with the cabinet door unlatched
  3. Verify that you have Red axis status LEDs lit on the drive immediately upon powerup, and that the Green "DF" LED comes on after the control software has started up.
  4. Release Emergency Stop
  5. Verify that the Green "UV" and "USV" LEDs have come on
  6. Do not press CYCLE START to home yet
  7. Select Slow, Continuous jog mode
  8. With one hand on Emergency Stop, jog each axis in each direction: X-, X+, Y-, Y+, Z-, Z+
  9. If all axes move smoothly in all directions, then go ahead and press CYCLE START to start the homing sequence.
  10. If any axis fails to move as expected, in spite of being well clear of any limit switches or stops, then make note of the error message in the message box on the screen, and e-mail or call your service technician for assistance.

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Copyright © 2009 Marc Leonard
Last updated 12-Feb-2009 MBL