Double Flash RedGC420tHas video

Zebra GC420t Double Flash Red: Ribbon Error Troubleshooting

The double flashing red light on the Zebra GC420t indicates a Ribbon Out error. This status occurs when the thermal transfer ribbon sensor detects that the ribbon spindle is not spinning or has run out.

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Common causes

  • 1The thermal transfer ribbon is empty, torn, or broken.
  • 2The cardboard ribbon core is slipping on the take-up spindle.
  • 3The printing method driver setting is mismatched with the physical media setup.

Solutions

Repair and Adjustment Methods

1. Secure Spindle Core and Check Tension

If the ribbon core is slipping on the spindle, the sensor won't detect rotational movement:
  • Open the printer cover.
  • Verify that the notches on the left side of the cardboard core are locked onto the notches of the ribbon supply spindles.
  • Tighten the ribbon manually by rotating the take-up gear forward until all slack is removed.

2. Verify Print Driver Configuration

Using direct thermal labels (which do not use ribbon) with the driver set to 'Thermal Transfer' will trigger this error:
  • Open Control Panel > Devices and Printers on your PC.
  • Right-click the Zebra GC420t and choose Printing Preferences.
  • Navigate to Options or Page Setup and verify that 'Print Method' is set to Direct Thermal if you do not use ribbon, or Thermal Transfer if ribbon is installed.
  • Click apply and print a configuration card.

3. Inspect the Optical Ribbon Sensor

If dust covers the sensor lens, it may register a false out-of-ribbon state:
  • Remove the ribbon roll.
  • Gently blow compressed air into the interior mechanical gears on the left side to clean any particles blockading the rotation sensor.

Steps to follow

  1. 1

    Check Driver Settings

    Switch driver mode to Direct Thermal (no ribbon) or Thermal Transfer (with ribbon).

  2. 2

    Align Ribbon Spindle

    Align cardboard notches with the spindle teeth and wind up slack manually.

  3. 3

    Clear State

    Lock down the mechanism cover and tap the Feed button to resume printing.

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Frequently asked questions

This usually indicates the ribbon core is spinning loosely on the shaft, or your driver settings are incorrectly forcing a Direct Thermal print option while ribbon is present.

Yes, by configuring the driver settings to 'Direct Thermal'. The printer will stop monitoring ribbon movement entirely.