LCD screen not working | Prusa Knowledge Base

The LCD screen is vital for operating the printer. Should you encounter any kind of trouble, such as a dead screen, corrupted text, or other issues, please refer to the guide below.

First of all, unscrew the LCD screen from the printer frame, remove both M3x10 screw holding it the LCD board in the plastic casing, and remove it from the casing. See if the problem still appears when the LCD is not pressed by the casing.

Squares or random signs on the LCD screen

Firmware updates are necessary to keep your printer up to date. However, the installation of incorrect firmware can lead to letter corruption on the LCD screen. There's an easy fix, though:

Go to the Drivers and Apps page and download the correct firmware version for your printer setup.
Once you download the correct zip file, simply follow How to update firmware (MK3S+/MK3S/MK3) and you are good to go.

There is a small chance the printer's LCD screen can glitch out by electrostatic discharge when inserting the SD card. Try to turn the printer off and on again.

Blank LCD screen

This problem usually appears only on user-assembled printers. If your printer's LCD screen remains blank or displays corrupted symbols after you turn on the printer, there is a chance it is caused by incorrect wiring. Follow these steps to fix the issue.

If the screen is glowing but is completely blank, you may simply need to adjust the contrast. Please see LCD screen contrast adjustment (i3).

Turn the printer off, remove the power cord and unplug the printer's USB cable from your PC
Open the cover of the electronics board.
- Original Prusa i3 EINSY RAMBo board can be accessed by reverting STEP 31 in the Electronics Assembly.
- Original Prusa i3 miniRAMBo board can be accessed by reverting STEP 21 in the Electronics assembly.
Double-check that all cables are properly seated and they are not visibly damaged. Depending on the model of your printer, please refer to the following guides for information on how to make sure the cables are properly connected: Einsy RAMBo electronics wiring (MK3/MK3S/MK3S+) and Mini RAMBo electronics wiring (MK2S, MK2.5, MK2.5S).
Make sure that the LCD ribbon cables are not warped at any spot and that they are fully seated in the correct connector with the correct orientation.
If you suspect that the LCD ribbon cables connectors are not firmly seated in the slots, disconnect the LCD ribbon cables and check the slots for any bent pins. If there are bent pins, you can use tweezers to fix them. However, be very careful not to break the pin(s) completely.
Gently push the connectors back into their respective slots. Then reconnect the power cord and turn the printer on again.
If none of the above resolved the problem, turn the printer off again and try to unplug both of the cables, lay them down on a flat surface and gently stretch them. Then plug them back in and turn on the printer.

13 comments

Tom M

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I just put together a MK3S+ and after performing a first layer calibration, I removed the build plate to clean off the filament. The LCD then turned into white squares except for the top left corner. I turned the printer off then proceeded to follow the steps for updating drivers and firmware. After that didn't work, I unplugged both LCD cables, checked for bent pins, straightened and slightly stretched the cables, then plugged them back in, ensuring the correct cable went to the correct ports. The screen is still showing white squares.

Same Old Shane

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For situations like these, it is best to contact prusa support directly via the chat option on the eshop, or via email at [email protected] It could be a few different things that they can assist you with checking to see what the issue may be.

Blog0893

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Buenas, al encender la impresora I3 MK3S en la pantalla aparecen unos cuadrados en vez de letras, sin poder ajustar ni leer nada, comprobé todas las conexiones y sustituí los cables:
-Extruder heater
-Heatbed thermistor
Por que aparentaban estar deteriorados, de nuevo arranque la impresora y de nuevo, se veía el fondo de la pantalla LCD azul y los cuadrados en vez de letras.
Además probé instalar de nuevo Firmware en PrusaSlicer del PC, pero al tener la última versión me decía: Error avrdude.
No se que más puedo hacer llevo varias semanas leyendo el montaje de la impresora 3D-I3 MK3S y tengo todo igual que las instrucciones, pero no logró solucionar nada.

Blas Palencia

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Hola. Siento mucho leer sobre este problema.
Por la descripción parece un problema con la unidad LCD o sus cables.Para confirmar esto, intenta conectar la impresora con el cable, y Pronterface, a un ordenador.
https://help.prusa3d.com/es/article/pronterface-y-cable-usb_2222
Contáctanos luego con el resultado y te ayudaremos hasta que esté resuelto.
https://help.prusa3d.com/es/article/atencion-al-cliente_2287
Un saludo,

Txema

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I have a screen problem with a MK3s bought back in August 2020, where a couple of characters in the first two rows do not appear completely. I have verified that last Firmware is in the printer, dismounted the LCD case to verify if it was pressing too much the LCD, and also unplugged the cables from both sides (Einsy Rambo and LCD) for clearing the contacts with a specific contact cleaner, but still the problem is not solved.
I have uploaded a photo with the problem of the screen to the forum:
https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/problems-with-my-screen/#post-579241

David

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Hi! Sometimes, the conductive pad right underneath the LCD looses contact. I had this happen for example due to thermal expansion when bringing the printer into a cold room. Check the reply in the forum thread :)

Txema

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Great!!! I could tighten six out of the eight pads and the pixels have returned. Thank you very much!!

jeremy.b8

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Weird issue with my LCD. It worked fine for the past 2-3 years. Stock build. The LCD shows white squares with various symbols. I can press "stop" and it will show the "Original Prusa i3" then go back to white squares with various symbols. I've reflashed with 3.10.1 and 3.10.0 with the same issues. Reseated the cables on both ends. Swapped cables (from ports to other port, don't have extra cables to test for known good). Any ideas?

William H. - Official Prusa

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This behaviour is normally what you will see if you flash MK2.5/MK2 fw to a MK3, or vice versa.

luiselzayas

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My screen went white after a short print and it hasn't go back. When I turn the printer on the screen looks normal until the rebooting loading bar finishes that it goes white. I've contacted prusa but they ran out of ideas on what could be the issue. So far I've updated the firmware, disconnected and connected all cables, check for continuity on the screen cable, and done every suggestion. If you have any idea, please let me know.

William H. - Official Prusa

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Prusa Support will not give up on you:) Please continue cooperating with them. They know their stuff, but some cases can be harder to assess. This comment field is unfortunately not the platform for such troubleshooting.