Centroid CNC control sales, service, training and support
Swapping a Centroid SERVO1 Drive
This document applies to Centroid DC servo control systems using
either the SERVO1 or QUADDRV1 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
Make sure that all wires and cables are clearly labeled, so you
can get them reconnected in the right order.
Make note of the positions of the limit switch DIP switches
and the drive fault DIP switches:
The limit switch DIP switches are a bank of eight.
In most cases these will all be toggled
down, towards the circuit board. Yours may vary though, so
check them and write it down or make a sketch.
QUADDRV1 (4-axis drive) limit switches have an additional bank of
two switches. In most cases these will both be toggled up, away
from the circuit board. Check and make note.
The drive fault DIP switches are a bank of two, often set back
slightly under the cover plate. In most cases these will both be
toggled up, away from the board. Check and make note.
Disconnect all wires and cables:
Optical fibers "DATA" and "SYNC"
Limit switch cable
Drive fault cable
Z axis brake wires, if present
Motor power leads, RLY1/RLY2 wires, Motor bus wires
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.
Remove mounting screws securing heat sink to cabinet wall
Remove the drive:
If your drive has a finned heat sink, slide it carefully out
through the slot in the side of the cabinet. You may need
to remove the cover plate from the face of the drive in
order for it to fit through the slot.
If your drive has a flat heat sink, bring it directly out the
front of the cabinet.
Snug down all ten terminal screws across the bottom of the drive,
so they do not come loose and get lost in shipping.
Pack the drive for shipping with the cover plate and terminal
screws facing up (logic power supply down). If available, pack
the drive in an anti-static bag. Provide 2-4 inches of padding
material all around the drive.
Installing the Drive
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.
Install the drive:
If the new drive has a finned heat sink, slide it carefully in
through the slot in the side of the cabinet.
If the new drive has a flat heat sink, install it directly
from inside the cabinet.
Install mounting screws from outside the cabinet wall. Get all the
screws started before fully tightening any of them.
Plug in the 120VAC connection to the logic power supply,
in back of drive
Reconnect all wires and cables:
Optical fibers "DATA" and "SYNC"
Limit switch cable
Drive fault cable
Z axis brake wires, if present
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.
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
Press in the Emergency Stop pushbutton
Power up the control, with the cabinet door unlatched
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.
Release Emergency Stop
Verify that the Green "UV" and "USV" LEDs have come on
Do not press CYCLE START to home yet
Select Slow, Continuous jog mode
With one hand on Emergency Stop, jog each axis in each direction:
X-, X+, Y-, Y+, Z-, Z+
If all axes move smoothly in all directions, then go ahead
and press CYCLE START to start the homing sequence.
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.
Make sure that all wires and cables are clearly labeled, so you
can get them reconnected in the right order.