e120HL-4570CDW

Brother HL-4570CDW Error E120: Laser Unit Failure

The Brother HL-4570CDW error E120 signifies a problem within the Laser Scanner Unit (LSU), which is responsible for projecting the image onto the photosensitive drum. When the internal circuitry detects that the laser motor is not rotating at the correct speed or the light is not hitting the drum, it triggers this error. This is a technical hardware failure that typically requires professional support to resolve.

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Common causes

  • 1Polygon laser motor seizure.
  • 2Contamination of the internal laser optical mirrors.
  • 3Diodal failure due to aging.
  • 4Faulty communication cable to the LSU board.

Solutions

Diagnóstico rápido

If you see E120, the printer is unable to synchronize its laser projection. If you hear a high-pitched whining sound followed by a system lock, the laser motor has likely stalled.

Solución paso a paso

  1. Hard power-off: Power off the unit for at least 5 minutes to allow the polygon motor to reset.
  2. Optics cleaning: Carefully wipe the laser scanner glass with a lint-free cloth if the unit is accessible.
  3. Cable check: Verify the connection between the main board and the laser assembly.

Prevención y mantenimiento

Avoid using sub-par generic toners, as excess toner powder can drift into the laser assembly and contaminate the mirrors.

Cuándo llamar a un técnico

If the error persists after resetting, the polygon motor or the laser diode has likely failed, necessitating a full unit replacement.

Ficha técnica del equipo

  • Technology: Color Laser
  • Speed: 28 ppm
  • Connectivity: USB, Ethernet
  • Consumables: TN-315 series
  • Usage: Corporate environment
  • Official Drivers / Firmware

Steps to follow

  1. 1

    Hard power-off

    Power off the unit for at least 5 minutes to allow the polygon motor to reset.

  2. 2

    Optics cleaning

    Carefully wipe the laser scanner glass with a lint-free cloth if the unit is accessible.

  3. 3

    Cable check

    Verify the connection between the main board and the laser assembly.

Frequently asked questions

It is a fault in the Laser Scanner Unit (LSU), the part that projects the image onto the drum.

Minor dust cleaning is possible, but mechanical failure of the laser motor requires professional service.

Always use high-quality TN-315 cartridges to avoid toner leakage into the delicate laser optics.

Keep the printer in a stable, dust-free environment and avoid sudden power cuts.

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