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OmniTurn G4 CNC: Servo's Won't Turn On


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If the servos are not coming on, the most common reason is a bad Emergency stop contact, either in the control E-stop button or the E-stop on the Operator's Station.

You will need a voltmeter set to DC volts. (If no voltmeter, scroll down to "Test Using Paper Clip Jumper").

Turn the control on: stop at the screen that shows the "Servos off or external halt.." message.


CRDY at switches
  1. If not about 12.5VDC at #1, then possible issue with CN1 or CNFP5 Image of schematic with switches and front-panel connect card
    CN1, CNFP4, CNFP5, and CNFP9
    on the Front Panel Connect Card
  2. If not about 12.5VDC at #2, then replace the Front Panel E-Stop switch (p/n 995​-12​-103)
  3. If not about 12.5VDC at #3, then replace the OpSta E-Stop switch (p/n 998​-12​-104)
  4. If not about 12.5VDC at #4, then replace the Front Panel E-Stop switch (p/n 995​-12​-103)
  5. If not about 12.5VDC at #5, then possible issue with CNFP5 or CNFP9 Image of schematic with switches and front-panel connect card
    CN1, CNFP4, CNFP5, and CNFP9
    on the Front Panel Connect Card
  6. If not about 12.5VDC at #6, then replace the Control On switch (p/n 995​-12​-201)
  7. If not about 12.5VDC at #7, then possible issue with CN1 or CNFP4 Image of schematic with switches and front-panel connect card
    CN1, CNFP4, CNFP5, and CNFP9
    on the Front Panel Connect Card
  8. If about 12.5VDC at #7, move the black meter lead to #7b and press the Servos ON button. If not about 12.5VDS at #7b with button depressed, the Servos ON switch is bad (p/n 995-12-102)


Test Using Paper Clip Jumper (NOTE: The jumper doesn’t need to be screwed into place if two people are available; one person can hold the jumper on the terminals and the other can see if servos turn on)

To check those contacts, jumper the top two terminals
Jumper top terminals on E-Stop Switch
on the Control's Emergency stop button. (Set control power off before connecting jumper) If the servos will turn on after you do that, the problem is in the Operator's Station. (Emergency Stop Switch Assembly, p/n 998​-12​-104).

If they still won’t come on, move the jumper to the bottom two terminals
Jumper bottom terminals on E-Stop Switch.
on the E-stop switch. Remove contact blocks from operator to make it easier. (Set control power off before connecting jumper). If the servos will turn on with jumper on bottom terminals, the problem is in the Control's Emergency stop button. (Emergency Stop Switch Assembly, p/n 995​-12​-103). Remove bottom jumper.

! DO NOT RUN THE MACHINE WITH JUMPER ON TERMINALS OF E-STOP SWITCH! !
Remove this jumper after testing for servos on! With this jumper you have no E-Stop.

If the servos won’t come on with jumper on bottom of E-stop switch, the problem is not in the E-stop switches. Use the paper clip to jumper between #7 and #7b on Servos ON switch. If that turns on the servos, replace the Servos ON switch (p/n 995-12-102). If that doesn't work, you will need voltmeter to troubleshoot. Remove all jumpers before proceeding.


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