OmniTurn G3 CNC:
No yellow "Control On" lamp or no display on monitor

NOTE: Light blue text links to pictures; click picture to close.

No yellow "Control On" lamp:
The yellow power light indicates that the computer power supply is working. The 12V should come on when the system is turned on and the computer power supply is working.
If the monitor displays the start-up information, replace the bulb (#53 bayonet).

If there is also no display on the monitor, first do the following:

• Be sure there is power to the machine.
• Check that the CNC Control is plugged into socket on back of machine. On very early machines, the CNC may be plugged into a wall-socket.
• Check that the fan in the CNC is running. (Remove blue cover if you cannot hear the fan).
• If fan is on, the CNC has power. Go to "Fan is ON" below.
• If fan is not on continue with the following steps:
• Check the fuse on the back of the CNC Control.
• If the CNC is powered by step-down transformer in spindle drive cabinet, check that disconnect on spindle cabinet is ON.
• If the CNC is powered by step-down transformer in spindle drive cabinet, check the fuses on step-down transformer in spindle cabinet. NOTE: On GT75 machines with step-down transformer, the worklamp will light if these fuses are ok.
• If any of these fuses are blown, the servo power supply bridge rectifier , located on CNC top chassis, is probably bad. P/N 995-15-002.
Located in CNC, on Top Chassis.
Located in CNC, on Top Chassis.
• If these fuses are ok, but the fan is not on, the Control ON switch could be bad or unplugged from the connect card. Go to "Fan is NOT ON" below.

Fan is ON: If the fan is on, the Control On lamp may have blown and not been replaced, and the monitor might also be bad. Or the computer power supply may have failed. If the issue is a bad monitor, the control will boot up as normal, but there will be no display on the monitor.

To quickly determine if it’s just the monitor, set power on, then wait a minute for the computer to boot up, then press the "Caps Lock" key and see if the "Caps Lock" light goes on. If it does, click here to troubleshoot the monitor.

If the "Caps Lock" light does not come on when you press the key, do the following to check the computer power supply:

• Fish out one of the spare computer power supply connectors .
• With the controller power on, use DC voltmeter to measure between black and yellow wires.
• If you do not read between 11.5 and 12.5 volts DC, order AT Power Supply, p/n 995-16-009.

If you do read between 11.5 and 12.5 volts DC:

• Locate J6 on the connect card.
• Use DC voltmeter to measure between the metal clips that hold the black wire on J6, and the metal clips that hold the clear wire on J6.
• If you read between 11.5 and 12.5 volts DC on J6, you may have bad video card or bad motherboard. Call 541-332-7004 or email service@omniturn.com

Fan is NOT ON: If the fan is not on, but the fuses check good, the Control On switch may be defective, or disconnected.

To verify that the Control On switch is properly connected, first set control power OFF, then check the following:

• Locate TS1 on the connect card.
• Unplug and examine TS1. Verify that all three wires are securely held by the terminal screws, then plug TS1 back in.
• Verify that all three wires are connected to the switches:
  • The black wire goes from TS1 to Control On switch terminal 13;
  • the white wire from TS1 to E-Stop switch terminal 12, then to Control On switch terminal 14.
  • The green wire goes from TS1 to E-Stop switch terminal 11.

If TS1 and wires to switches look good, do this:

• Set control power on and verify that fan is still not on.
• Set voltmeter to AC volts, and put leads between Control On switch terminal 13 and the body of Spindle Override. If fuses are all good, you should measure about 110VAC.
• Move lead from terminal 13 to terminal 14: if you do not have same voltage as terminal 13, order Control On switch, p/n 995-12-101.

For reference, front panel wiring schematic is available here.