8M PCB - How it Works and Troubleshooting Guide

How it Works

The 8M Relay PCB is an option that adds (8) additional outputs to the I/O PCB. Additional outputs can be used to activate probes, auxiliary pumps, or clamping devices.

8M outputs are added in banks of eight (8). Bank addressing on the 8M PCB is done through selectable jumpers. For the first 8M PCB, jumpers must be placed at JP1 and JP5. For a second 8M PCB, jumpers must be set to JP2 and JP5.

Classic Haas Control (CHC): Parameter 352 is used to route the 8M commands from the I/O PCB to the added 8M PCBs. The default value for the parameter is 1. When the parameter is set to 2, functions M21-M28 for the 8M outputs are routed to the first 8M PCB. Please refer to the user manual for detailed descriptions on all of the M-Codes and functions related to the 8M option.

Next Generation Control (NGC): Only the outputs on the I/O PCB are addressable with M21-M25, M51-M55, and M61-M65. You must use M29, M59, and M69 with P codes to activate the relays on the bank. The P codes for the first 8M bank are P90-P97.

The 8M PCB uses eight single-pole double-throw (SPDT) relays to provide the user with normally closed (NC) or normally open (NO) outputs. Each relay has an indicator LED that turns ON when that relay is activated.

The I/O PCB sends command signals to the 8M PCB through a 16-pin ribbon cable. The 8M PCB requires 12 VDC. This voltage comes from the power distribution PCB (PSUP).

note: The 8M PCB option does not provide an output voltage, it only provides an NC or NO switch point for the user interface.
Symptom Possible Cause Corrective Action Section
The M21-M28 relays on the 8M PCB do not activate when commanded. There is a problem with the power to the 8M PCB. Troubleshoot the power to the 8M PCB. 1
The M21-M28 relays on the 8M PCB do not activate but their corresponding LED indicates they are on. There is a problem with the relays. Make sure the relays are not damaged. 2

Section 1

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.

Corrective Action:

Measure the voltage at P2 on the 8M PCB. Use a multimeter with needle-tip probes. The voltage must be 12 VDC.

note: Do not measure the voltage with the cable disconnected.

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.

Section 2

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.

Corrective Action:

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.

Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.

Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.

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