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

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.

• Locate the Auxiliary Power Supply.
  Locate the Auxiliary Power Supply
• Put the RED meter lead onto white wire
  RED Meter Lead on Auxiliary Power Supply in the connector on the Auxiliary Power Supply.
• To check meter and connection, touch the BLACK meter lead to the chassis:
  Touch BLACK meter lead to chassis. you should read about 12.5VDC.
• Locate CN401
  CN401 on the Connect Card on the Connect Card.
• Touch the BLACK meter lead to CN401-17 (CRDY).
  Meter lead at CN401 CRDY. It’s the 9th pin down from the square pin. You should read about 12.5VDC.
  CRDY test OK.
• If the voltage is about 12.5VDC, leave the RED meter lead on white wire
  Meter Lead on Auxiliary Power Supply in the connector on the Auxiliary Power Supply, and touch the BLACK meter lead to the terminals on the E-Stop and Control On switches as shown in the image below.

1. If not about 12.5VDC at #1, then possible issue with CN1 or CNFP5
   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
   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
   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)

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• If the voltage is NOT about 12.5VDC, at CN401-17, the 5AX card isn’t pulling the CRDY pin down, possibly because of a bad output driver chip, or there’s a bad connection in the CN401 ribbon cable.

  To check the ribbon cable, turn off the CNC and unplug ribbon cable
  CB401 Ribbon Cable between 5AX and Connect Card between CN401 on 5AX card and connect card. Examine the connectors to insure the ribbon is securely in place. Replug the ribbon cable, power up the CNC and see if you can turn on the servos. If not, recheck the voltage at CN401-17 as above: (RED meter lead on auxiliary power supply
  RED Meter Lead on Auxiliary Power Supply and BLACK meter lead at CN401-17).
  Meter lead at CN401 CRDY.

  If still not 12.5VDC, you will need to replace the driver IC U417.
  Driver IC U417

  To replace U417, unplug the power cord for the control, remove the screws that hold the triangular brackets
  5AX Mounting Brackets to the chassis, and tilt the card back to get access. Remove U417
  5AX Driver IC's U414 (spare) and U417 (the lower right IC) and set it aside, then remove U414 and plug it in to U417’s socket.

  When removing the IC's from their sockets, be careful not to bend the leads- work them out gradually by slipping a small screwdriver or similar tool under one end, then the other. When plugging them into their sockets make sure that none of the leads get bent.

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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.