I/O PCB - How it Works and Troubleshooting Guide (Classic Haas Control)

How it Works

The I/O PCB is the interface between the control and the all of switches, motors, sensors, solenoids etc. The I/O PCB is split into two parts, inputs [1] and outputs [2]. Most are independent from one another.

Inputs: The I/O PCB receives input signals from all of the switches and sensors. These signals are isolated and sent to the Maincon or Mocon trough a 32 pin ribbon cable (550) that connects at P63 on I/O PCB to P10 on Maincon or Mocon.

Outputs: The I/O PCB gets the output signals from the Maincon PCB. These signals are received via four 16 pin ribbon cables that connect to P61(540), P64(520), P65(510) and P70(530).

I/O PCB Voltage Requirements: It has its own internal power supply that generates 24 VDC, 12 VDC and 5 VDC. These voltages are used to power the inputs, axis brake, etc.

  • It requires 5 VDC and 12 VDC from the Low Voltage Power Supply (LVPS).
  • It requires 3-phase 120 VAC to drive solenoids, oil pump, fans and other 120 VAC devices. Also this 3-phase 120 VAC gets rectified (converted) to 160 VDC to drive the tool change motors.

  • There is 1-phase 120 VAC from the GFCI to drive the worklight and the high intensity lights.
  • It requires 3-phase 240 VAC to drive the coolant pump, TSC motor, hydraulic power unit on a lathe.
  • It requires 3-phase 240 VAC to drive the chip auguer or conveyor.
note: The plug numbers listed apply to Classic Haas Control I/O PCB rev S or higher.

Symptom Possible Cause Corrective Action Section
There is no voltage output. There is a faulty supply voltage to I/O PCB or a Circuit Breaker on the Power Distribution PCB is tripped. Check the voltages to I/O PCB. Also check for a tripped circuit breaker or blown fuse on the Power Distribuition PCB. 1
There is a faulty connection. Make sure all connections and cables are securely connected and are not damaged. 2
There is a possible I/O PCB failure. Check all voltages, cables going to I/O PCB, Also check for burnt components or traces on the I/O PCB. 3

Multiple alarms are generated.

On the DIAGNOSTICS page all inputs showing 1.

On the DIAGNOSTICS page one or more Inputs do not change state when the switches or sensors are triggered.

There is a faulty supply voltage to I/O PCB or a Circuit Breaker on the Power Distribution PCB is tripped. Check the voltages to I/O PCB. Also check for a tripped circuit breaker or blown fuse on the Power Distribuition PCB. 1
There is a faulty connection. Make sure all connections and cables are securely connected and are not damaged. 2
There is a possible I/O PCB failure. Check all voltages, cables going to I/O PCB, Also check for burnt components or traces on the I/O PCB. 3

Section 1

Symptom: There is no voltage output. Multiple Alarms are generated. On the DIAGNOSTICS page all inputs showing 1. On the DIAGNOSTICS page one or more Inputs do not change states when the switches or sensors are triggered.

Possible Cause: There is a faulty supply voltage to I/O PCB or a Circuit Breaker on the Power Distribution PCB is tripped.

Corrective Action:

Check Voltages to I/O PCB

note: The plug numbers listed below apply to Classic Haas Control I/O PCB rev S or higher. Measure the voltage on the backside of the corresponding connector on the I/O PCB. Use a volt meter equipped with needle tip probes.

  • Check the 5 VDC and 12 VDC at P60 [1] from the Low Voltage Power Supply (LVPS).
  • Check the 3-phase 120 VAC at P56 [2] these voltages drive the solenoids, oil pump, fans and other 120 VAC devices. If no voltage present. Check the CB6 circuit breaker on the Power Distribuition PCB.
  • Check the 1-phase 120 VAC at P83 [5] this voltage drives the worklight and the high intensity lights. If no voltage present. Check the GFCI outlet on the side of the machine to make sure is not tripped. Also check the GFI/Worklight circuit breakers on the Power Distribuition PCB.
  • Check the 3-phase 240 VAC at P44 [3] these voltages drive the coolant pump, TSC motor, hydraulic power unit on a lathe. If no voltage present. Check the Coolant and TSC circuit breakers on the Power Distribuition PCB.
  • Check the 3-phase 240 VAC at P39 [4] these voltages drive the chip auguer or conveyor. If no voltage present. Check the Conveyor circuit breaker on the Power Distribuition PCB.
  • If there is voltage present. Check cables and connections see section 2.

Section 2

Symptom: There is no voltage output. Multiple Alarms are generated. On the DIAGNOSTICS page all inputs showing 1. On the DIAGNOSTICS page one or more Inputs do not change states when the switches or sensors are triggered.

Possible Cause: There is a faulty connection.

Corrective Action:

  • Make sure the power cable or cables for the system are seated properly and are secure in place.
  • Make sure the connector pins are seated properly and are secure in place.
  • Clean contaminated connectors. Re-seat the connectors and make sure they are secure.
  • Perform a visual inspection on the cables. Look for signs of damage or puncture. Replace cables if there is visible damage.
  • Check the cable connections between P64, P65, P70, and P61 [2] on the I/O PCB and P11, P12, P13, P14 [1] on the Mocon/Maincon. These cables are the same and can be interchanged with each other for testing.
  • Some systems have the power to the worklight protected by a GFCI outlet on the side of the machine, make sure the GFCI is not tripped and that is functioning properly.

Section 3

Symptom: There is no voltage output. Multiple Alarms are generated. On the DIAGNOSTICS page all inputs showing 1. On the DIAGNOSTICS page one or more Inputs do not change states when the switches or sensors are triggered.

Possible Cause: There is a possible I/O PCB failure.

Corrective Action:

  • Verify on the DIAGNOSTICS screen that the output was commanded.
  • Look for burned contacts in the relays. Replace the K9 - K12 relays as needed. (Only for Tool changer, APC motor, Servo Bar 300 carriage motor issues only)
  • Look for burnt components or traces on the I/O PCB.
  • Perform all tests measurements and inspections listed in sections 1 to 3.
  • If all voltages are OK, cables are OK and have no signs of visual damage, motors have checked OK, sensors have tested OK, and the problem still reoccurs, then the I/O PCB may have failed.
  • Replace the I/O PCB.

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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