The Z-Probe in the 22 IDEX printer relies on two magnets located on the toolhead and a PCB (printed circuit board) at the back of the machine. For ESD protection, this PCB uses optocouplers to enable or disable the flow of current between the two magnets. By default, the circuit is disabled (no current flows), and it is only activated ("allowed") during AutoCalibration or Z-homing.
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Current Flow Enabled
- The PCB at the back “allows” current to flow from one magnet to the other when calibration or Z-homing is started.
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Normally Closed Switch
- The Z-Probe itself acts as a normally closed switch. As long as the probe is not triggered, current passes through it.
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Trigger Detection
- When the probe is pressed (triggered), it breaks the flow of current, signaling the firmware that the probe has contacted the surface.
A pair of LEDs on the small PCB at the back of the machine provide real-time feedback:
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Green LED
- Illuminates only when the Z-Probe is “allowed” or programmatically activated.
- Stays off at all other times.
- If it’s lit when the probe should be disabled, you may have a short to the printer’s frame or other wiring issues.
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Blue LED
- Lights up when the Z-Probe is picked up and ready (probe is physically attached to the magnets).
- Turns off when the probe is triggered (pressed).
- Its on/off state should not affect the Green LED.
| Z-Probe Status |
Green LED |
Blue LED |
| Not Allowed, Not Picked |
Off |
Off |
| Allowed, Not Picked |
On |
Off |
| Allowed, Picked, Not Triggered |
On |
On |
| Allowed, Picked, Triggered |
On |
Off |
| Not Allowed, Picked, Not Triggered |
Off |
On |
| Not Allowed, Picked, Triggered |
Off |
Off |
Important: If the Blue or Green LED behave differently than described, this typically indicates a wiring or grounding issue.
You can also monitor the probe’s status in the printer’s Web Interface:
- Default Z-Probe Value:
1000
- When Picked Up: The value changes to
0
- When Triggered: The value reverts to
1000
Note: The Web Interface may have a slight delay in updating these values.
¶ Scenario A: Machine Ignores the Probe and Runs into the Build Plate
Symptoms:
- The printer attempts to home Z even when the probe is not physically picked up.
- The Z-Probe is recognized as installed (or “picked”) when it isn’t.
- During Z homing with the probe attached, the printer does not stop when the probe contacts the build plate.
Probable Cause:
A short circuit (wiring issue) is causing the probe signal to read as “always closed,” so the machine believes the probe is never triggered.
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Check Grounding Wires
- Each hotend (Tool 0 and Tool 1) has a grounding lug (gold-colored crimp).
- Ensure the lug only touches the heat block and not any other metal component on the toolhead.
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Inspect All Z-Probe Wires
- Look for damaged insulation, pinched cables, or any obvious signs of wear along the path from the Z-Probe magnets to the distribution block.
- Also check fan wires, temperature sensor wires, and heater wires in case they are worn or frayed and causing a short to the probe circuit.
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Check Connections
- Lightly tug each wire at the distribution block or PCB terminals.
- Gently remove wires by pressing the orange tab (if applicable), inspect the ends, and reinsert securely.
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Check the PEEK Interface Screws
- Remove the PEEK interface (the part joining the extruder to the hotend).
- Verify the screws do not protrude or sit flush with the extruder housing. They must be recessed to avoid contact with other metal parts.
- Repeat for both extruders (Tool 0 and Tool 1).
If the machine still runs the nozzle into the build plate after confirming none of the above are causing a short, please contact support for further guidance.
Symptoms:
- The printer attempts to pick the probe, but the system does not “see” the probe once attached.
- You might observe a red light or an error message indicating the probe is not detected.
Probable Cause:
The probe circuit is open (no continuity), so the machine never receives the “picked” signal.
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Verify Electrical Connections
- Trace the wiring from the magnets on the toolhead to the distribution block.
- Remove wires from the distribution block by pressing the orange tab, inspect the wire ends, and re-seat them.
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Inspect Wire Integrity
- Check the wires at the magnets themselves. Ensure the cable is firmly attached and not damaged.
- If possible, use a multimeter in continuity mode to confirm each wire is unbroken.
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Test the Z-Probe Sensor
- Gently click the probe by hand; it should have a crisp, audible click.
- If using a multimeter:
- Not Triggered: There should be continuity between the two magnet contacts.
- Triggered: There should not be continuity (the switch opens).
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Clean the Magnets
- Wipe both the toolhead magnets and the Z-Probe magnets with a cloth to remove debris or filament residue that could prevent a solid electrical connection.
If the probe still fails to be recognized after performing these checks, please reach out to our Support Team for deeper diagnostics.
- Power Off if Unsure
Always power down and unplug the machine before removing panels, disconnecting wires, or removing the PEEK interface.
- Wear Gloves
The hotend, nozzle, and nearby metal components can be very hot.
- Keep Everything Clean
Filament debris, dust, or other contaminants can interfere with the probe docking station and wiring.
By identifying which scenario applies—wiring short (Scenario A) or open circuit (Scenario B)—you can focus on the correct set of troubleshooting steps. Check all grounding wires, cable integrity, and connections, and ensure that all screws and magnets are properly seated. In many cases, these steps resolve the issue. If problems persist or you notice unusual LED behavior, contact our Support Team for further assistance.