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LCD screen not working

Relevant for

Plus 1.75 mm
MK2.5
MK2.5S
MK3
MK3S
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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:

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).
  1. Turn the printer off, remove the power cord and unplug the printer's USB cable from your PC
  2. 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.
  3. 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).
  4. 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.
  5. 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.
  6. Gently push the connectors back into their respective slots. Then reconnect the power cord and turn the printer on again. 
  7. 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.