Printer does not turn on (Form 4 and Form 4L generation)

Damaged or malfunctioning components may cause your Form 4 or Form 4L generation printer to fail to power on, freeze, not initialize, shut down unexpectedly, or experience display issues. Although these symptoms might seem similar, they usually result from different underlying causes, most often related to the display, motherboard, power supply, or the system on module (SOM).

Symptoms

  • Printer does not turn on
  • Screen is completely dark
  • Screen backlight is on but no image is displayed
  • Screen shows the Formlabs butterfly splash screen, but the loading bar is stuck
  • No activity from lights on the motherboard
  • No activity from lights on the power supply

Causes

  • Defective or damaged display: The display is not functioning and shows no image, but the device is otherwise operating normally.
  • Defective motherboard: The motherboard has a number of voltage converters to provide different supply voltages. Damaged components in the voltage converter circuits can prevent the printer from turning on.
  • Defective SOM: The Raspberry Pi CM4 SOM runs the printer's operating system. If the SOM is defective, then the device will not turn on.
  • Defective power supply: If the power supply does not output DC power, the motherboard will not receive power, preventing the printer from turning on.

Troubleshooting steps

Check if the printer is accessible via PreForm

If the printer does not appear to turn on but shows other signs of activity, such as fan noise or motor movements, the touchscreen may be disconnected or damaged. In this case, the printer may still be accessible via PreForm. To check this:

  1. Connect your computer to the printer via USB.
  2. Open PreForm and check if you can connect to the printer to upload a print job.
  3. If you can connect to the printer via PreForm, it is operating normally but the screen is not functioning. Reseat both ends of the display cable following the appropriate guide for your printer.
  4. If reseating the display cable does not resolve the issue, replace the display. Form 4 and Form 4L generation touchscreen assemblies are available on the Formlabs Store. Follow the appropriate guide for your printer to replace the touchscreen.

Check the motherboard power LEDs

Danger:

This procedure involves operating your printer with a panel removed. Do not touch any electrical components on the printer while the panel is removed and the printer is powered on.

If the printer is not available in PreForm, you can diagnose which component has failed by checking the four power LEDs on the printer’s motherboard.

  1. Disconnect the printer from its power source.
  2. Access the motherboard.
Right panel screws on a Form 4 generation printer
Lower left panel screws on a Form 4L generation printer

Form 4 generation: Use a 2.5 mm hex driver to remove the four screws securing the right panel to the printer. Set the right panel and the screws aside.

Form 4L generation: Use a 2.5 mm hex driver to remove the four screws securing the lower left panel to the printer. Set the left panel and the screws aside.

  1. Reconnect the machine to power and observe the motherboard power LEDs, shown below. Follow the steps in the flowchart below to check each of the power LEDs.
Power indicator LEDs on the Form 4 and Form 4L generation motherboard
Flowchart for checking power LEDs
  1. If the 48V LED is not lit, check the power supply LED.
  2. If the 48V LED is lit but the 12V LED is not lit, replace the motherboard. Form 4 and Form 4L printers use the same motherboard, which is available on the Formlabs Store. Follow the appropriate guide for your printer to replace the motherboard.
  3. If the 12V LED is lit but the 5V LED is not lit, turn off the printer, remove the SOM, then turn the printer back on and re-check the 5V LED. Follow the appropriate guide for your printer to remove the SOM.
    1. If the 5V LED is still not lit, replace the motherboard.
    2. If the 5V LED is lit, the SOM needs to be replaced. Contact Formlabs Support or your authorized reseller for a replacement SOM.
  4. If the 5V LED is lit but the 3V3 LED is not lit, the SOM needs to be replaced. Contact Formlabs Support or your authorized reseller for a replacement SOM.
  5. If all four power LEDs are lit, contact Formlabs Support or your authorized resellerfor more assistance.

Check the power supply LED

Danger:

This procedure involves operating your printer with a panel removed. Do not touch any electrical components on the printer while the panel is removed and the printer is powered on.

If the 48V LED on the motherboard is not lit, the power supply may be defective and not providing power to the motherboard or there is a fault on the motherboard that is interfering with power delivery. To determine which is the case, check the activity LED on the power supply.

  1. Disconnect the printer from its power source.
  2. Access the power supply. Follow the appropriate guide for your printer, linked below. Stop at the section titled “Removing the power supply.”
  3. Power on the printer and observe the power supply LED, shown below.
Power supply LED on a Form 4 generation printer
Power supply LED on a Form 4L generation printer

Power supply LED on a Form 4 generation printer

Power supply LED on a Form 4L generation printer

  1. If the LED is not lit, power off the device again and disconnect the power cable from the motherboard. The power cable has a square connector, located next to the green SOM on the motherboard. Disconnect the connector by pushing down on the tab and sliding the cable out of the connector. Take care not to pull on the wires.
  2. Turn the printer on again. If the LED still does not turn on, the power supply needs to be replaced.
  3. If the power supply LED turns on once the motherboard is disconnected, then it is more likely that the motherboard is defective and needs to be replaced.
Disconnecting the power cable from the motherboard on a Form 4 generation printer