Required Supplies:
Formlabs:
- Backlight Unit
- 2.5 mm hex driver (included in the Form 4 tool caddy)
Third-party:
- Nitrile gloves
WHITE PAPER
Replacing the Form 4 Backlight Unit
Replacing the Form 4 Backlight Unit
The Form 4 generation printer Backlight Unit contains an LED array and lenses to produce and focus the light that cures resin during the printing process. A damaged Backlight Unit may prevent the printer from printing properly.
Use this guide to remove and replace the Backlight Unit on a Form 4 generation printer.
Estimated time: 30 minutes
Preparing the workspace
Overview: Prepare the printer and a dust-free workspace for replacing the Backlight Unit.
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.
Notice:
Wear gloves and hold the resin tank by the tank grips on either side to avoid contamination or damage to the underside of the tank.
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
Warning:
Resin may cause skin irritation or an allergic skin reaction. Wear gloves when handling liquid resin or resin-coated surfaces. Wash skin with plenty of soap and water.
Open the printer cover and clean any resin pooled on and around the LPU with paper towels. Dampen the paper towels with isopropyl alcohol if necessary to fully remove the resin.
Danger:
Fire hazard. IPA is flammable. Keep containers closed, and keep out of the reach of children.
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.
Danger:
Performing maintenance on the printer while it is plugged in increases the risk of electric shock. Never remove the back panel of the printer while the printer is plugged in. Never reconnect the printer to power while the back panel is uninstalled.
Removing the Backlight Unit
Overview: Position the printer on its back to access and remove the Backlight Unit.
Notice:
Performing maintenance with the Backlight Unit removed increases the risk of contamination inside the optical cavity. Take care to prevent dust or debris from falling inside the printer.
Step 1: Position the printer
Ensure that the build platform, resin cartridge, resin tank, and mixer have been removed from the printer to prevent damage. Carefully rotate the printer so that it is resting on the back surface with the bottom facing you. Leave at least 15 cm (6 in) of clear tabletop in front of the printer when it is lying down.
Step 2: Remove the Backlight Unit screws
Use a 2.5 mm hex driver to remove the four socket cap screws that secure the Backlight Unit to the bottom of the printer. Do not remove the button head screws. Set the screws aside.
Step 3: Separate the Backlight Unit from the printer
Grip the two handles on the Backlight Unit. Carefully pull the Backlight Unit away from the printer and pivot it until it rests on the work surface.
Notice:
Take care not to touch the components inside the exposed optical cavity.
Step 4: Unplug the backlight driver cable
Hold the connector by its plastic housing and gently squeeze the plastic tab to unplug the backlight driver cable from the Backlight Unit. Do not pull on the individual wires.
Step 5: Unhook the backlight driver cable
Unhook the backlight driver cable from the clips along the side of the Backlight Unit.
Step 6: Disconnect the LED fan cable
The LED fan cable is located in the bottom-left of the optical cavity. Squeeze the plastic retaining clip and unplug the LED fan cable from the printer. Do not pull on the wires.
Step 7: Remove the Backlight Unit
Once all the cables are disconnected, remove the Backlight Unit from the printer. Set aside for disposal with electronic waste.
Installing the replacement Backlight Unit
Overview: Connect and install the replacement Backlight Unit.
Step 1: Position the replacement Backlight Unit in front of the printer
Place the replacement Backlight Unit on the workspace in front of the printer. Orient the Backlight Unit with the backlight driver cable connected at the front-left.
Notice:
Do not touch the exposed lenses. Doing so may contaminate the lenses and lead to repeated print failures.
Step 2: Connect the LED fan cable
Connect the LED fan cable connector to the LED fan cable at the back of the printer. The connector makes an audible and tactile click when secured.
Step 3: Connect the backlight driver cable
Connect the backlight driver cable to the Backlight Unit. The connector makes an audible and tactile click when secured.
Step 4: Route the cable
Route the cable along the edge of the Backlight Unit and push it gently under the cable clips until the cable is flush with the surface of the Backlight Unit.
Step 5: Organize cables
Some internal cables may have moved during the repair procedure. Move any loose cables so they are positioned alongside the metal tab in the optical cavity.
Step 6: Install the Backlight Unit
Lifting with the two handles, gently slide the Backlight Unit into the printer. Ensure the Backlight Unit is fully seated.
Notice:
- Take care not to pinch the wire bundles at the back of the machine.
- If the Backlight Unit is contaminated during the repair procedure, apply a small amount of clean IPA to a PEC*PAD and wipe the surface of the Backlight Unit to remove contamination or resin. Allow the Backlight Unit to air dry before installing it.
Step 7: Secure the Backlight Unit
Using a 2.5 mm hex driver, hand-tighten the four socket cap screws on the bottom of the printer to secure the Backlight Unit.
Finalizing the repair
Overview: After installing the new Backlight Unit, 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.