Zebra ZD621 troubleshooting guide: errors, faults and fixes

Short answer: According to Zebra, the ZD621's cover, which carries the printhead, is not latched, or the head-open switch needs repair. Close the cover by pressing down on its two front corners until the latches click; if the alert is still displayed, call in a technician.

Likely cause

The Zebra guide describes this alert when the printer receives a print command or a press of FEED while the cover is open or not properly closed. Second cause cited: the head-open switch needs servicing.

What to do

1. Close the cover by pressing down on its two front corners, on the top.
2. Check that you hear and feel the latches click: the cover is then locked for printing.
3. If the alert persists even though the cover is properly latched, the head-open switch is at fault: do not keep trying.

When to call a technician: if the alert persists with the cover latched, Zebra states that the head-open switch must be repaired by a technician.

Sources: Alert: Printhead Open (opens in a new window) · Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The ZD621 does not detect any media in the media path: empty roll, missing label at the end of the roll, or printer set for labels while continuous media is loaded. Reload the roll, close the cover then press FEED or PAUSE; after changing the media type, run a new SmartCal calibration.

Likely cause

According to Zebra, the alert appears when a print is requested, FEED is pressed or a job is in progress and the printer does not detect any media. The guide cites four causes: no roll loaded; a missing label which, with some manufacturers, marks the end of the roll; a printer set for non-continuous media (gap or black mark) while continuous media is loaded; media that can no longer be detected (corrupted memory or failed component).

What to do

1. Empty roll: load media, close the printer, then press FEED or PAUSE if necessary to resume printing.
2. Missing label at the end of the roll: open the printer, replace the empty roll and resume printing. Leave the printer switched on during the operation, otherwise the current job is lost.
3. Continuous media loaded while the printer expects labels: check that the movable media sensor is in its default centre position, then run a new SmartCal calibration if needed (see the calibration entry).
4. Media still not detected: reload the printer firmware.

When to call a technician: if the media is still not detected after reloading the firmware, Zebra says to call a technician.

Sources: Alert: Media Out (opens in a new window) · Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The ZD621t has reached the end of the ribbon: genuine Zebra ribbons end with a reflective leader that the printer reads as the end of the ribbon. Remove the used ribbon, install a new roll, close the cover then press FEED once, or PAUSE, to resume.

Likely cause

Zebra states that the printer stops mid-job, or reports the alert as soon as a job is sent, when it detects the end of the ribbon. The SUPPLIES light only reports this ribbon-out condition in thermal transfer mode: in direct thermal (ZD621d), no ribbon is used.

What to do

1. Open the cover and remove the used ribbon.
2. Install a new roll of ribbon, then close the printer.
3. Press FEED once, or PAUSE, to resume printing.

The other causes on the Zebra page (ribbon cartridge missing or not recognised) only concern the cartridge-based ZD421, not the ZD621.

Sources: Alert: Ribbon Out (opens in a new window) · Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The printhead has overheated and the ZD621 pauses to let it cool down. After a large print job, there is nothing to do: printing resumes on its own. If the room is too hot or the printer is exposed to the sun, move it.

Likely cause

Zebra cites two causes: a large job with a lot of printing, or an ambient temperature above the printer's operating range. Direct sunlight can raise the temperature inside the printer.

Caution: The printhead can be hot enough to cause severe burns: let it cool before touching it.

What to do

1. Leave the printer paused: printing resumes automatically once the head has cooled down.
2. If the alert keeps coming back, move the printer to a cooler place, out of the sun, or lower the room temperature.

If STATUS and PAUSE are both flashing red, the guide states that the printer must cool down and then be restarted (see Printhead Shutdown).

Sources: Alert: Printhead Over Temp (opens in a new window) · Status – Printhead Operation (opens in a new window) · Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The ZD621's printhead has overheated. Zebra says to switch off the printer, wait several minutes for it to cool completely, then switch it back on.

Likely cause

According to the “Status – Printhead Operation” table in the Zebra guide, this state indicates an overheating printhead.

Caution: The printhead can be hot enough to cause severe burns: let it cool before touching it.

What to do

1. Switch the printer off.
2. Wait several minutes for the printhead to cool completely.
3. Switch the printer back on.

The Zebra page does not link this message to a light state. The light table does, however, state that STATUS and PAUSE flashing red indicate printhead overheating, which requires letting the printer cool down and then restarting it.

Sources: Status – Printhead Operation (opens in a new window) · Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The printhead is colder than the temperature needed to print correctly, most often because the room is too cold. Switch off the ZD621, move it to a warmer place and let it warm up gradually.

Likely cause

Zebra cites two causes: an ambient temperature below the printer's operating range, or a faulty printhead thermistor (the sensor that measures its temperature).

Caution: Zebra warns that a rapid change in temperature can cause condensation in and on the printer.

What to do

1. Switch off the printer and move it to a warmer room.
2. Let it warm up gradually, without sudden heating.
3. If the room is already at the right temperature, switch off the printer by holding the POWER button for 5 seconds, wait for it to shut down completely, then switch it back on.

When to call a technician: if the alert persists after restarting in a room at the right temperature, the printhead thermistor is probably faulty: Zebra says to call a technician.

Sources: Alert: Printhead Under Temp (opens in a new window) · Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The ZD621 does not have enough free memory to store a graphic, a format, a bitmap image or a font. Delete items that are no longer used or reduce the print area of the label format.

Likely cause

According to Zebra, the printer cannot store the data in the requested memory location. The second line of the message shows the operation that failed for lack of space.

What to do

1. Read the second line of the message to find out which operation is short of memory.
2. Free up memory by changing the label format or the printer settings to reduce the print area.
3. Delete graphics, fonts or formats that are no longer used.
4. Check that the data is not being sent to a storage device that is missing or unavailable.

Sources: Alert: Out of Memory (opens in a new window) · Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: On a ZD621 fitted with the colour touch display, a yellow or red home screen background indicates that the printer is in an alert or error state. Read the message displayed, then open the matching entry in the lookup table.

Likely cause

The Zebra guide states that the colour touch display, offered as a factory option on the ZD621, shows operator alert and error messages, and that the home screen background turns yellow or red when the printer is in an alert or error state.

What to do

1. Read the message shown on the display (for example Media Out, Ribbon Out or Printhead Open).
2. Find this message in the lookup table and apply the matching entry.
3. ZD621 printers with a touch display keep the five STATUS, PAUSE, DATA, SUPPLIES and NETWORK lights: their state confirms the type of alert.

The home screen also gives access to the menus, the Wizards and the shortcuts; the image of the printer can be rotated through 360 degrees there.

Source: ZD421 and ZD621 Series Desktop Printers User Guide (P1123730-05EN), “Controls and Indicators” and “Color Touch Display and Controls” chapters (opens in a new window) – ZD421 / ZD621 user guide (PDF) (official documentation).

Short answer: On the ZD621, SmartCal calibration is started from the ready state by holding PAUSE and CANCEL down together for two seconds. The printer feeds and measures a few labels, sets its detection levels, then the STATUS light returns to solid green.

Likely cause

Zebra explains that SmartCal automatically determines the media type (gap / notch, black mark or continuous) and measures its characteristics. A new calibration is useful when you change media type; a roll of the same type, from the same supplier and the same batch does not need one, as the printer adapts on its own to small variations.

Official SmartCal calibration procedure

1. Load the media correctly and, for thermal transfer (ZD621t), the ribbon. Close the cover.
2. Switch the printer on with POWER and wait for the ready state: STATUS light solid green.
3. Hold PAUSE and CANCEL down together for two seconds, then release.
4. The printer feeds and measures a few labels, then adjusts its detection levels. At the end, the STATUS light is solid green.
5. For a new roll from the same batch, one or two presses of FEED are enough to synchronise the labels.

If SmartCal does not recognise the media or calibrates it incorrectly, Zebra refers you to manual calibration. On a ZD621 with a touch display, it is in the Print > Sensors > Manual Calibration menu.

Sources: Running a SmartCal Media Calibration (opens in a new window) · Issue: Labels Are Distorted in Size or Print Area Start Position Varies (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: Zebra calls this a registration fault: media sensor badly positioned, sensors not calibrated for the media in use, platen roller slipping or a communication problem. Check the movable sensor, run a SmartCal calibration, then a manual calibration from the display if the skipping continues.

Likely cause

The guide cites four causes: media badly loaded or movable media sensor badly adjusted; sensors not calibrated for the length, properties or sensing type of the media (gap / notch, continuous or mark); platen roller slipping or damaged, as rollers wear over time; communication cables or settings.

What to do

1. Check that the movable media sensor is positioned for your media type and its sensing mark.
2. Run a SmartCal calibration (see the calibration entry).
3. If labels are still being skipped, perform a manual calibration from the Print > Sensors > Manual Calibration menu on the touch display.
4. Clean or replace the platen roller if it slips (see the platen roller entry).
5. Check the communication cables and settings (see the serial link entry).

Source: Issue: Labels Are Distorted in Size or Print Area Start Position Varies (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: This is the behaviour selected in the ZD621's Power Up Action (power-up) and Head Close Action (printhead closing) settings. Depending on the option, the printer calibrates, measures the label length, feeds to the first registration mark or does not move.

Likely cause

The Zebra guide describes five options common to both settings. CALIBRATE adjusts the sensor levels and thresholds, determines the label length and feeds to the next label. SHORT CAL sets the thresholds without adjusting the sensor gain, determines the length and feeds. LENGTH determines the length using the current sensor values, then feeds. FEED feeds to the first registration mark. NO MOTION does not move the media: you must position it yourself or press FEED.

What to do

1. On the touch display, open System > Settings > Power Up Action for the power-up behaviour.
2. Open System > Settings > Head Close Action for the behaviour when the printhead is closed.
3. Choose the appropriate option from CALIBRATE, SHORT CAL, LENGTH, FEED and NO MOTION.

Source: ZD421 and ZD621 Series Desktop Printers User Guide (P1123730-05EN), “System Menu” chapter (Power Up Action, Head Close Action) (opens in a new window) – ZD421 / ZD621 user guide (PDF) (official documentation).

Short answer: According to Zebra, a platen roller fouled with adhesive, dust or oils makes the media slip or stick. Remove the roller, clean it with isopropyl alcohol and let it dry for one minute; if the media still sticks or jams, replace it.

Likely cause

The platen acts both as the print surface and as the drive roller. Zebra asks you to remove deposits promptly (adhesive, dirt, dust, oils), as they can damage the printhead or make the media slip and stick. A platen that keeps sticking or causing jams after cleaning must be replaced.

Caution: The swab or cloth must be barely damp, never soaked. Never wash or rub a linerless roller: Zebra states that this damages it permanently.

Official roller cleaning procedure

1. Open the cover, and the label dispenser door if one is installed, then remove all media from the roller area.
2. On both sides, pull the bearing locking tabs towards the front of the printer, then rotate them upwards.
3. Lift the roller out of the frame, then slide the gear and both bearings off the shaft.
4. Standard roller: clean it from the centre outwards with a swab or lint-free cloth barely moistened with 99.7% isopropyl alcohol. Change swabs until the whole surface is clean, and go over it once more if there is heavy adhesive build-up.
5. Roller for linerless media: use no alcohol and do not rub; dab the surface with the adhesive side of a piece of linerless media.
6. Put the bearings and gear back on the shaft, refit the roller with the gear on the left, then fold the tabs back towards the rear until they click.
7. Let it dry for one minute before closing the printer or loading labels.

Zebra identifies the rollers by colour: standard black (203 dpi) or grey (300 dpi), linerless reddish-brown (203 dpi) or brown (300 dpi).

Sources: Cleaning and Replacing the Platen (opens in a new window) · Recommended Cleaning Schedule (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: Zebra recommends cleaning the ZD621's printhead every time you load a new roll, with a new cleaning pen. Remove the ribbon if there is one, wipe the dark area of the printhead from the centre outwards, then wait one minute before closing.

Likely cause

Adhesive and dirt left by the media build up on the printhead. Zebra states that cleaning with every new roll promotes optimal operation; the maintenance schedule in the same guide sets a minimum of one cleaning every five rolls.

Caution: The printhead gets hot during printing: do not touch it, to avoid damaging it and injuring yourself. Follow antistatic precautions when working on the printhead or the electronics under the cover: an electrostatic discharge can damage or destroy them.

Official printhead cleaning procedure

1. If a transfer ribbon is installed (ZD621t), remove it.
2. Use a new cleaning pen: a pen that has already been used can damage the printhead with contaminants from its previous use.
3. Wipe the dark area of the printhead from the centre outwards, to push the adhesive left by the edges of the media out of the media path.
4. Wait one minute for everything to dry before closing the printer or reloading the ribbon.

On recent ZD621 Healthcare printers, the plastics withstand UV and disinfectants, and the sealed controls are cleaned along with the outside of the printer. Zebra refers you to its disinfecting and cleaning guide for Healthcare printers for the approved products.

Sources: Cleaning the Printhead (opens in a new window) · Cleaning the Printhead – ZD421/ZD621 Thermal Transfer Printers (opens in a new window) · Recommended Cleaning Schedule (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: Zebra offers the print quality report (FEED self test): the ZD621 prints a series of labels at several darkness settings and two speeds. Keep the setting that gives the best barcodes at the speed you use, as each media can require a different darkness.

Likely cause

According to Zebra, each media type can require a different darkness setting. The test is used to find the one that produces barcodes that meet the specification.

What to do

1. Run the print quality report (FEED self test) described in the Zebra user guide.
2. The printer prints two series of seven labels, one at low speed and the other at high speed, with a relative darkness ranging from -3 to +3 around the current setting.
3. The test speeds are 51 mm/s (2 ips) and 152 mm/s (6 ips) at 203 dpi, and 51 mm/s (2 ips) and 102 mm/s (4 ips) at 300 dpi.
4. Each label shows its relative darkness and speed: compare the barcodes (or their ANSI grade if you verify them) and keep the darkness that gives the best result at your print speed.
5. Apply this darkness setting to the printer.

If the print is still faded with the right darkness, clean the printhead (see the cleaning entry).

Source: Printing a Print Quality Report (FEED Self Test) (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: According to Zebra, the ribbon material (wax, wax-resin or resin) may not suit the media (paper, coated paper or synthetic). Use a ribbon suited to your labels and do not exceed the maximum print speed recommended for that ribbon.

Likely cause

Zebra links these defects to an incompatibility between the ribbon and the media, and to a print speed that is too high for the ribbon in use.

What to do

1. Check that the ribbon type (wax, wax-resin or resin) suits your media (paper, coated paper or synthetic).
2. Replace the ribbon with one that is compatible with this media.
3. Set the print speed no higher than the maximum speed recommended for the ribbon.

The Zebra page gives the speed instruction for the ZD421's ribbon cartridge; the ZD621t uses roll ribbon, whose maximum speed is given by the ribbon manufacturer.

Source: Issue: General Print Quality Issues (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The ZD621 does not recognise the installed printhead: either it is not a genuine Zebra printhead, or it is incorrectly installed and the printer cannot read its resolution (dpi). Install a genuine Zebra printhead, correctly fitted.

Likely cause

According to the “Status – Printhead Operation” table in the Zebra guide, “Printhead Resolution Error” means that the printer cannot read the printhead's resolution type, because it is incorrectly installed or has been replaced by a non-Zebra printhead. “Unauthorized Printhead Error” means that the installed printhead is not a genuine Zebra printhead.

Caution: Let the printhead cool before handling it: Zebra warns of a risk of severe burns. Also follow antistatic precautions, as an electrostatic discharge can destroy the printhead.

What to do

1. If the printhead has just been replaced, check that it is fitted correctly by following the replacement procedure in the Zebra user guide.
2. If the printhead is not a genuine Zebra part, install a genuine Zebra printhead to be able to print.

Sources: Status – Printhead Operation (opens in a new window) · Standard Interface Controls (opens in a new window) · Cleaning the Printhead (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: On the ZD621, a solid red NETWORK light indicates an Ethernet or Wi-Fi fault; flashing red, a Wi-Fi association in progress; flashing orange, a Wi-Fi authentication in progress; flashing green, a weak Wi-Fi signal. Print the network configuration label (FEED and CANCEL for two seconds in the ready state) to check the settings.

Likely cause

The Zebra guide details the NETWORK light: solid orange for a 10Base Ethernet link, solid green for a 10/100 Ethernet link or a strong Wi-Fi signal, solid red for an Ethernet or Wi-Fi fault.

What to do

1. Note the state of the NETWORK light and compare it with the states described above.
2. Print the network configuration label: hold FEED and CANCEL for two seconds in the ready state, or CANCEL for two seconds during power-up. On the touch display, use Connection > Networks > Print: Network Info.
3. After changing the network settings, reset the print server with Connection > Networks > Reset Network: Zebra states that this reset is required for the changes to take effect.

Unlike the ZD421, the ZD621 has a factory-installed Ethernet port and serial port, according to the Zebra guide.

Sources: Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide · ZD421 and ZD621 Series Desktop Printers User Guide (P1123730-05EN), Ethernet and Wi-Fi light tables and “Connection Menu” chapter (opens in a new window) – ZD421 / ZD621 user guide (PDF) (official documentation).

Short answer: The label format is not recognised and the DATA light does not flash: Zebra points to the communication settings. Check the driver or software settings and, over a serial link, that the port settings match and the condition of the cable.

Likely cause

Zebra cites three causes: incorrect communication settings in the driver or software; over a serial link, a flow control protocol (handshake) or port settings that differ between the printer and the computer; again over a serial link, a cable that is not a standard DTE or DCE type, that is damaged or that is too long for the RS-232 limits.

What to do

1. Check the communication settings of the printer driver or software, if they apply to your setup.
2. Over a serial link, compare the printer's flow control protocol and port settings with those of the computer.
3. Over a serial link, check that the cable is a standard DTE or DCE type, in good condition and within the RS-232 length limits.

Source: Issue: Label Job Sent, No Data Transfer (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The ZD621 receives the data but does not recognise the format. Zebra cites ZPL prefix and delimiter characters that differ between the printer and the format, communication settings that differ, or an incorrect label format.

Likely cause

According to Zebra, three causes prevent the printer from interpreting a received format: the ZPL command prefix (COMMAND CHAR) and delimiter (DELIM./CHAR) set on the printer do not match those of the format; the computer's communication settings do not match those of the printer; the label format contains errors.

What to do

1. Check the ZPL command prefix and delimiter on the printer, compare them with those of the label format and correct whichever is wrong.
2. Check that the computer's communication settings match those of the printer.
3. Review the label format using the Zebra ZPL programming guide.
4. To go further, turn on communications diagnostics mode: in the ready state, hold PAUSE and FEED for two seconds, or use System > Program Language > Diagnostic Mode on the touch display. The printer then prints all the data it receives; the ZPL command ~JE turns this mode off.

Sources: Issue: Label Job Sent, Data Transfers, But No Print (opens in a new window) – ZD421 / ZD621 user guide · ZD421 and ZD621 Series Desktop Printers User Guide (P1123730-05EN), “System Menu” chapter (Diagnostic Mode) (opens in a new window) – ZD421 / ZD621 user guide (PDF) (official documentation).

Short answer: Zebra attributes this symptom to serial communication settings that differ between the printer and the computer. Check that the flow control and the other serial link settings are identical on both sides.

Likely cause

According to Zebra, the printer's serial communication settings do not match those of the host system.

What to do

1. Open the communication settings of the printer driver or software, if they are accessible.
2. Check that the flow control matches that of the host system.
3. Check that the other serial link settings also match.

The ZD621 has a factory-installed serial port; this case concerns setups that use it.

Source: Issue: Label Job Sent, Skips Labels or Prints Bad Content (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: The blade of the optional cutter is jammed and no longer moves correctly, because of media, adhesive or a foreign object. Switch off the ZD621 by holding POWER for 5 seconds, wait for it to shut down completely, then switch it back on; if the error persists, call a technician.

Likely cause

Zebra states that media, adhesive or a foreign object is preventing the cutter blade from moving. The status table calls it “Cut Error (Binding)”.

Caution: Zebra specifies: never remove the cutter cover (bezel) and never insert objects or fingers into the mechanism. Do not use unapproved tools, cotton buds or solvents (including alcohol): they can damage the cutter, shorten its service life or jam it.

What to do

1. Hold down the POWER button for 5 seconds to switch off the printer.
2. Wait for the printer to shut down completely.
3. Turn it back on.

When to call a technician: if the cut error persists after restarting, Zebra says to call a technician: the cutter contains no user-serviceable parts.

Sources: Alert: Cutter Error (opens in a new window) · Status – Typical Operating Conditions (opens in a new window) · Standard Interface Controls (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: According to Zebra, the optional battery is reporting a fault: temperature out of range, end of life or a failed component. Let it return to room temperature, then check its charge; if the fault persists, replace it.

Likely cause

Zebra cites three causes: battery too hot or too cold, battery at the end of its life, or a component failure. The battery light table distinguishes solid red (internal error) from flashing red (charging error).

What to do

1. Let the battery return to room temperature, then check its charge again.
2. If the light stays red, remove the battery from the printer and check its condition by putting it on charge.
3. If the fault persists, replace the battery.

The battery fits in the ZD621's optional battery base. According to the Zebra table, when no charge bars light up, the battery needs recharging and the printer cannot be switched on using the battery.

Sources: Issue: Battery Displays a Red Indicator (opens in a new window) – ZD421 / ZD621 user guide · ZD421 and ZD621 Series Desktop Printers User Guide (P1123730-05EN), battery light table (opens in a new window) – ZD421 / ZD621 user guide (PDF) (official documentation).

Short answer: Most often, the changed settings have not been saved (ZPL command ^JU not sent before switching off) or a command in the label format overwrites them. Switch the printer off and on again to check that they are kept, and check the commands being sent.

Likely cause

Zebra cites four causes: changes not saved; syntax errors or commands that disable a setting or reset it to its default value; control, command or delimiter characters that differ between the printer and the format; a problem with the main logic board, such as corrupted firmware.

What to do

1. Switch the printer off and on again and check that the settings have been kept.
2. Check the command syntax and usage in the Zebra ZPL programming guide.
3. Print a configuration report, or look at the System > Language menu on the touch display, to check the control, command and delimiter characters, then compare them with your format.
4. If nothing works, restore the factory defaults (see the reset entry), then reload the printer firmware.

When to call a technician: if the printer does not return to normal operation after restoring factory defaults and reloading the firmware, Zebra says to contact a technician: the main logic board is not user-serviceable.

Source: Issue: Settings are Lost or Ignored (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: On a ZD621 with a touch display, open System > Settings > Restore Defaults and choose PRINTER (printer settings other than network), NETWORK (print server) or LAST SAVED (last save). From the buttons, hold FEED and PAUSE down during power-up to reset the printer settings to factory defaults.

Likely cause

Zebra specifies that loading the defaults erases manual changes: you will need to reconfigure the printer afterwards.

Official procedure for restoring factory settings

1. On the touch display, open System > Settings > Restore Defaults.
2. Choose PRINTER to reset all printer settings except the network (ZPL command ^JUF).
3. Choose NETWORK to reset the wired or wireless print server (^JUN); a Wi-Fi printer then re-associates with its network.
4. Choose LAST SAVED to reload the settings from the last permanent save (^JUR).
5. Without using the display: hold FEED and PAUSE down during power-up to reset the printer settings to factory defaults.
6. Another option cited by Zebra: the “Load printer defaults” action in Printer Tools in Zebra Setup Utility.

If Protected Mode is enabled, this setting cannot be changed from the front panel; Zebra refers you to its Link-OS PrintSecure administration guide.

Sources: System > Settings > Restore Defaults (opens in a new window) · Issue: Settings are Lost or Ignored (opens in a new window) – ZD421 / ZD621 user guide (official documentation).

Short answer: According to the Zebra guide, the ZD621R ships with factory-installed RFID support and the colour touch display. The RFID wizard on the display configures the RFID subsystem, and the RFID menu gives access to RFID status, RFID test and calibration, and read and write power.

Likely cause

The RFID antenna is located between the platen roller and the movable media sensor slide. The guide describes a dedicated RFID menu: RFID Status, RFID Test, RFID Calibrate, Read Power, Write Power, RFID Antenna, valid and void label counters (RFID Valid Count, RFID Void Count), RFID Program Position and Read RFID Data.

What to do

1. From the home screen, open Wizards then the RFID wizard, which configures how the RFID subsystem operates.
2. Do not send any data from the computer while using the wizards, as Zebra instructs.
3. Then use the RFID menu to view the RFID status, run an RFID test or calibration and monitor the valid and void label counters.

The ZD421 / ZD621 user guide has a chapter on the RFID menu (“RFID Menu”); refer to it for details of each setting.

Source: ZD421 and ZD621 Series Desktop Printers User Guide (P1123730-05EN), “Introduction”, “Printer Features” and “Color Touch Display and Controls” chapters (Printer Wizards) (opens in a new window) – ZD421 / ZD621 user guide (PDF) (official documentation).

Short answer: The Zebra guide provides for recalibrating the touch display: open System > Settings > Screen Calibration, then touch each cross-shaped target displayed.

Likely cause

The Screen Calibration setting recalibrates the touch display. It does not replace media calibration, which is done with SmartCal.

What to do

1. Open System > Settings > Screen Calibration.
2. Touch each cross-shaped target shown on the display.
3. To calibrate labels, use the SmartCal procedure (see the calibration entry).

Source: ZD421 and ZD621 Series Desktop Printers User Guide (P1123730-05EN), “System Menu” chapter (Screen Calibration) (opens in a new window) – ZD421 / ZD621 user guide (PDF) (official documentation).