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Selftest failed (XL)

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Last updated 3 months ago
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On the Original Prusa XL, the selftest checks for issues in the assembly of the printer, its wiring and the electronic components. It is the first part of the Calibration Wizard, which is prompted automatically when you turn on the printer for the first time or after a Factory reset (XL). After the initial calibration is completed, the selftest can be initiated in LCD Menu - Calibration - Selftest.

During the selftest, do not manipulate or touch the printer, unless the printer prompts an action with instructions on the display. 
If the printer is placed on an unstable surface or if there is another running 3D printer next to it, it may affect the accuracy of the calibration negatively. The printer should be placed on a stable surface. 

Selftest procedure checks

  • Test of the extruder and the print fan
  • Test of the X, Y, and Z axis
  • Proper connection of the heated bed and the hotend
  • Loadcell test
  • Setting up the filament sensor 

Selftest results

During the selftest, its results are shown on the screen, indicating success or fail for each point. Alternatively, the results can be shown at any time on the following path: LCD Menu - Calibrate - Diagnostics - Show selftest results.

Selftest errors

Test of the extruder and the print fan

The Original Prusa XL selftest procedure can determine which of the fans doesn't work. Check the one that is diagnosed as not OK.

  • Make sure that both of your fans are correctly connected to the Dwarf board.
  • Check for any blockage that could prevent either of the fans from spinning.

Test of the X, Y, and Z axis

The printer can determine if the components are moving correctly along each axis. 

In case of an issue on the X-axis, or on the Y-axis, make sure that there is no obstacle to the movement, and readjust the belt tension

Proper connection of the heated bed and the hotend

The selftest can determine a fault during the heating of a component, and the affected component. 

Heat up the affected component in [LCD Menu - Settings - Preheat], and see if any error appears: if it does, the error should have a QR code that redirects to the article that describes how to troubleshoot that particular error. 

Contact our customer support if you are on a different case, or in case of any doubts. 

Loadcell test

A functioning loadcell is fundamental for the Original Prusa XL to detect that the nozzle is close enough to the steel sheet for printing, and to avoid damage that would be caused by the nozzle digging into the steel sheet. 

  • Make sure that the loadcell is correctly connected to the Dwarf board. 
  • Make sure that the surface the printer is on is as stable as possible: any form of vibration propagated to the surface under the printer, or a not fully stable surface under the printer, might cause a false reading on the loadcell, causing it to fail the selftest. 

Filament sensor

The Original Prusa XL is equipped with two filament sensors: the first one is located on the side, close to the input of the PTFE tube where you feed the filament. The second one is located in the extruder. Both filament sensors are necessary for the correct filament retraction: when the sensor on the side detects that the filament has run out, the filament will be retracted in time. 

  • Make sure that the extruder filament sensor is correctly connected to the Dwarf board.
  • Make sure that the side filament sensor is correctly connected.
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