Hypertherm Powermax – Voltage Divider & Arc OK PWM Test Procedure

This guide will help you verify the voltage divider and Arc OK signal on a Hypertherm Powermax 45,65,85,105 set to a 50:1 ratio. Please follow all safety precautions and ensure the torch is clear before performing any test.

1. Voltage Divider Test (50:1)

Purpose: Ensure that the CPC port is outputting proper tip voltage for Torch Height Control (THC).

1. Set your digital multimeter to DC volts.

2. Identify CPC pins: Pin 5 = Voltage Divider (+), Pin 6 = Voltage Divider (–).

3. Connect red multimeter probe to Pin 5 and black probe to Pin 6.

4. Start a manual test cut or air fire the torch to maintain an arc.

5. Expected reading at 85A: Approximately 2.9V DC (145V tip volts ÷ 50).

6. If you see 0V or a very high reading, recheck torch arc, settings, and grounding.

2. Arc OK Signal Test

Purpose: Confirm that the plasma unit is correctly signaling a valid arc to your CNC controller.

7. Set multimeter to DC volts.

8. Identify CPC pins: Pin 12 = Arc OK, Pin 4 = Common.

9. Connect red probe to Pin 12 and black probe to Pin 4.

10. Torch Off: 0V expected.

11. Torch Firing: Approximately 24V DC expected.

12. This verifies the OK-to-Move signal is functioning.

Notes:

- If you're using a THC device, ensure the voltage divider ratio is configured correctly in its software.
- For the Powermax 85, typical cutting voltage at 85A is around 145V (2.9V on a 50:1 divider).
- Contact technical support if readings are significantly off or unstable.

Voltage Divider

CPC Port Pins 

3. PWM (Pulse Width Modulation) / Arc OK Signal Interpretation

Some systems use a PWM signal (often mislabeled) to represent the Arc OK output from the plasma cutter. On the Powermax 85, this is a 24V DC logic signal when the arc is valid.

1. Identify CPC Pins: Pin 12 = Arc OK (PWM-style logic), Pin 4 = Common.

2. Use a digital multimeter set to DC volts OR a logic probe.

3. Torch Off: Expect 0V between Pin 12 and Pin 4.

4. Torch Firing (valid arc): Expect approximately 24V DC between Pin 12 and Pin 4.

5. Some motion controllers interpret this as a PWM or 'OK-to-Move' input.

4. CPC Cable Pinout & Continuity Test

To verify your CPC cable is functional, you can perform a continuity test for each signal.

6. Power off the plasma unit and disconnect the CPC cable.

7. Using a multimeter in continuity mode (beep test), check the following pairs:

8. - Pin 5 to other end Pin 5 (Voltage Divider +)

9. - Pin 6 to other end Pin 6 (Voltage Divider –)

10. - Pin 12 to other end Pin 12 (Arc OK)

11. - Pin 4 to other end Pin 4 (Common)

12. All should show continuity (beep).

13. Wiggle the cable while testing to check for intermittent faults.

5. CandCNC PWM Module Test (for THC Systems)

This section applies to systems using the CandCNC Torch Height Control with a PWM (Pulse Width Modulation) voltage module. This module converts arc voltage from the plasma cutter for THC input.

14. Ensure the plasma system and CNC electronics are powered on.

15. Locate the 'Volts Test' button on the CandCNC PWM module.

16. For PWMII modules, unplug the two-wire 'Divided Volts' input from the plasma cutter.

17. Press and hold the 'Volts Test' button. The 'Volts ACT' LED on the module should begin flashing.

18. While holding the button, observe the CommandCNC screen: the THC voltage readout should display ~126–128V.

19. The 'ARC OK' indicator in MACH or CommandCNC should also light up, confirming signal flow.

20. If no voltage appears or the LED doesn’t flash, inspect the module, power source, or DTHC connection.

21. To test the DTHC card power: unplug the PWM module. A small LED on the DTHC card should light up.

22. If the LED stays off when the PWM is unplugged but turns off when plugged in, a short may exist in the PWM or cable.