Symptom: The M21-M28 relays on the 8M PCB do not activate when commanded.
Possible Cause: There is a problem with the power to the 8M PCB.
Measure the voltage at P2 on the 8M PCB. Use a multimeter with needle-tip probes. The voltage must be 12 VDC.
If the voltage is not correct, measure the voltage at P35 on the PSUP PCB. The voltage must be 12 VDC.
If the voltage is correct, cable 860 is at fault. If the voltage is not correct, go to diy.haascnc.com to troubleshoot the PSUP PCB.
Symptom: The M21-M28 relays on the 8M PCB do not activate but their corresponding LED indicates they are on.
Possible Cause: There is a problem with the relays.
Make sure the relays are not damaged. Make sure there is continuity between the contacts on the terminal block:
- Disconnect the cables from the terminal that is at fault.
- Activate the relay. Check for continuity across the Normally Open (NO) contact and the Common (COM) contact.
- De-activate the relay. Check for continuity across the Normally Closed (NC) contact and the COM contact.
Make sure the coil of the relay is not open:
- Remove the 8M PCB. On the back of the 8M PCB, measure the resistance across pins 1 and 5 of the relay at fault.
- If the measurement is open, the coil of the relay is open. The 8M PCB is at fault.