840CX820de

Lexmark CX820de error 840: Scanner failure

The Lexmark CX820de error 840 is a scanner hardware fault, indicating that the motor or sensors failed to complete the optical head calibration. This error typically disables scanning and copying functions while printing remains available.

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Common causes

  • 1Scanner motor failure.
  • 2Blocked sensor.
  • 3Flat cable connection fault.
  • 4Firmware calibration error.

Solutions

Diagnóstico rápido

If you see error 840, the scanner head cannot complete its initialization sequence. Check if the scanning bar tries to move upon startup.

Solución paso a paso

  1. Hard reset: Unplug the machine for a minute.
  2. ADF Inspection: Check for paper debris in the ADF entry.
  3. Clean glass: Use a microfiber cloth to ensure no smudges interfere with the sensor.
  4. Support: If the error persists, the scanner controller board may need inspection.

Prevención y mantenimiento

Avoid placing heavy objects on the glass. Use proper glass cleaners that leave no streaks.

Cuándo llamar a un técnico

Error 840 often requires a replacement of the scanner motor or the flat cable.

Ficha técnica del equipo

  • Technology: Color Laser MFP.
  • Component: Scanner module.
  • Connectivity: LAN / USB.
  • Consumibles: Lexmark 820 series.
  • Recommended use: Heavy enterprise work.
  • Official drivers / firmware

Steps to follow

  1. 1

    Restart

    Power off and on to reset the scanner head.

  2. 2

    Check ADF

    Ensure no paper debris is blocking the ADF unit.

  3. 3

    Update firmware

    Check if a firmware update addresses scanning bugs.

Frequently asked questions

It signals a failure in scanning unit initialization.

A power reset sometimes clears it; if not, service is required.

Lexmark 820 series cartridges.

Clean glass gently; avoid pressure.