1. GK888t User Guide
  2. Troubleshooting
  3. Print Quality Problems
  • GK888t Desktop Thermal Printer User Guide
Print Quality Problems

Print Quality Problems

Use a short description in a reference topic to briefly describe what the reference item does, what it is, or what it is used for.

No print on the label.

  • Check the type of media—The media may not be direct thermal media which is required when printing without ribbon (i.e. thermal transfer). See the test procedure Determining Thermal Media Types.
  • Check the media orientation—The wrong side of the media is facing up contacting the printhead. The media roll may not be outside wound.
  • Check the transfer ribbon winding—The outside of the ribbon must be wound with the transfer material facing out. See the following ribbon test procedures: Ribbon Test with Adhesive and Ribbon Scratch Test.
  • Check if the media is loaded correctly—Follow the instructions for Loading Roll Media. For printing using transfer ribbon, see Loading Transfer Ribbon.

The printed image does not look right.

  • The printhead is dirty. Clean the printhead (see Cleaning the Printhead).
  • The printhead is under temperature.
  • Adjust the print darkness and/or print speed.
    • Use the
      ^PR
       (speed) and
      ~SD
       (darkness) commands referenced in the ZPL Programming Guide.
    • Use the
      D
       (darkness/density) and
      S
       (speed) commands in the EPL Programmer’s Guide.
    • Manually adjust print darkness with the six-flash sequence of Feed Button Modes.
    • The Windows printer driver or the application software may change these settings and may require a change to optimize print quality.
  • The media being used is incompatible with the printer. Be sure to use the recommended media for your application, and always use Zebra-approved labels and tags.
  • The printhead has worn out. The printhead is a consumable item and will wear out due to friction between the media and printhead. Using unapproved media may shorten life or damage your printhead. Replace the printhead.
  • The platen may need cleaning or replacement. The platen (driver) roller may be losing traction due to:
    • Foreign objects have become attached to its surface,
    • The normal rubbery-smooth surface has become polished and slippery, or
    • There is damage to the normally smooth and flat print surface such as from box knife cuts.

There are long tracks of missing print (blank vertical lines) on several labels.

  • The printhead is dirty. Clean the printhead.
  • The printhead elements are damaged.

The printing does not start at the top of the label or misprint of one to three labels.

  • The media may not be threaded correctly. Follow the instructions for Loading Roll Media.
  • The printer needs to be calibrated. Refer to the two-flash sequence of Feed Button Modes.
  • ZPL Label Formats—The correct media sensor may not be activated. Manual calibration selects the media sensing method for the labels being used (refer to the
    ^MN
     command in the ZPL Programming Guide).
  • ZPL Label Formats—Verify that the Label Top (
    ^LT
    ) command is correctly set for your application (consult the ZPL Programming Guide).
  • EPL Label Formats—The correct media sensor may not be activated for label dispensing, blackline or notch sensing, or for Gap/Web sensing. Manual calibration selects the media sensing method for the labels being used (refer to the
    O
     and
    Q
     commands in the EPL Programmer’s Guide).
  • EPL Label Formats—Verify that the Set Label Length (
    Q
    ) command is correctly set for your application (consult the EPL Programmer’s Guide).

A ZPL label format was sent to, but not recognized by the printer.

  • Is the printer in PAUSE mode? If so, press the
    Feed
     button.
  • If the status LED is on or flashing, see Status Light Descriptions.
  • Make sure the data cable is correctly installed.
  • A communications problem has occurred. First, make sure that the correct communications port on the computer is selected. See Connecting your Printer to a Device.
  • Verify the correct Format and Control Prefix on the printer match what you are using in your ZPL programmed label format. The default Format (COMMAND CHAR) is Caret (^) character and the Control (CONTROL CHAR) is a Tilde (~) character. Verify the characters with the Configuration Status label printout. See the one-flash sequence of Feed Button Modes to print this label.

An EPL label format was sent to, but not recognized by the printer.

  • Is the printer in PAUSE mode? If so, press the
    Feed
     button.
  • If the printer has label dispensing enabled, the printer may be waiting for the label to be removed. The liner/web must be properly threaded through the label dispenser mechanism (peeler) to correctly operate in label dispense mode, see Label Dispenser Option.
  • If the status LED is on or flashing, see Status Light Descriptions .
  • Make sure the data cable is correctly installed.
  • A communications problem has occurred. First, make sure that the correct communications port (USB) on the computer is selected. Refer to Connecting your Printer to a Device .