Troubleshooting for a pilot relay fault

Diagnostic code 777

Diagnostic code 777 occurs when there is a fault related to the pilot relay.

Symptoms

Code Symptoms XPR® models XPR action Code cancels with...
777 The pilot-relay driver finds an overcurrent condition. All models None
  • Set process
  • Remote on-off

Safety consideration for the XPR460

For this procedure, make sure that you use the pilot-arc relay, NOT the cooler-power relay. When at least one remote on-off switch is set to OFF (disabled), 220 VAC electric power stays ON (active) to the input side of the cooler-power relay.
Plasma power supply image that shows the pilot-arc relay and the cooler-power relay.
1 Pilot-arc relay
2 Cooler-power relay

Corrective action

  1. Remove the power from the cutting system.
  2. Remove the control-side panel from the plasma power supply.
  3. Examine the control Printed Circuit Board (PCB) (PCB 1) in the plasma power supply.
  4. Disconnect J6 from the control PCB.
  5. Remove the cover from the pilot-arc relay.
  6. Use an ohmmeter to measure the coil resistance across wire 21 and wire 22.

    Look for a resistance of approximately 280 ohms (Ω).

  7. If the ohms value is more than 10% higher or lower than 280 ohms (Ω), replace the pilot-arc relay.
  8. If the ohms value is in the permitted range, make sure that you have the most recent XPR firmware.

    You can log in into the Xnet at www.hypertherm.com to download it.