The Light Processing Unit (LPU) fan filter prevents dust and debris from contaminating the Form 4 optical system. A dirty filter can cause issues with print quality; replace it to keep printing and to prevent damage to your printer.

Use this guide to replace the Form 4 LPU fan filter.

Estimated time: 15 minutes

Overview: Prepare the Form 4 and workspace for replacing the LPU fan filter.

Step 1: Remove the build platform

Remove the build platform first to avoid dripping resin onto the Light Processing Unit (LPU).

Step 2: Remove the resin cartridge

Remove the resin cartridge and close the vent cap to prevent resin from dripping off of the bite valve and into the printer.

Step 3: Remove and store the resin tank and mixer

Unlatch the mixer and resin tank. Remove the resin tank and cover it with its lid. Set the tank aside on a clean, flat surface.

Step 4: Prepare the workspace

Clear a workspace around your printer. Ensure that the workspace is well-ventilated and free of dust.

Step 5: Clean the printer

Open the printer cover and clean any resin pooled on and around the LPU with non-abrasive wipes. Dampen the wipes with isopropyl alcohol if necessary to fully remove the resin.

Step 6: Unplug the printer

Disconnect the power cable before continuing with maintenance. Do not perform maintenance on the printer while it is connected to power. Wait five minutes after disconnecting the printer from power before proceeding.

Overview: Remove the LPU fan filter from the printer.

Step 1: Remove the left panel retention screws

Use a 2.5 mm hex driver to remove the four screws securing the left panel to the printer. Set the left panel and the screws aside.

Step 2: Locate the LPU fan filter

The LPU fan filter sits in a housing next to the fan and includes a white pull tab on its side to allow for easy removal.

Step 3: Remove the filter

Using the white pull tab, carefully pull the LPU fan filter out of its housing. The LPU fan filter should come out easily. Set the LPU fan filter aside for disposal.

Overview: Install the replacement LPU fan filter.

Step 1: Install the replacement LPU fan filter

Grip the LPU fan filter by its metal frame and insert it into its housing until fully seated. Take care not to touch the filter directly. The LPU fan filter should slide easily into its housing without any resistance.

Step 2: Mount the left panel

Place the left panel on the printer. Ensure that the screw holes in the panel align with those in the printer frame and that it sits flush with the touchscreen assembly and the back of the machine.

Step 3: Install the left panel screws

Use a 2.5 mm hex driver to install the four screws that secure the left panel to the printer. Tighten the screws until snug.

Overview: After installing the new LPU fan filter, power on the printer and perform final checks.

Step 1: Power on the printer

Connect the power cable to the printer and the power supply. The printer initializes.

Step 2: Run a test print

Insert any missing consumables and upload and start a print. Perform a small test print to ensure that the printer works normally. Contact Formlabs Support or your authorized reseller to share the results of the procedure.