White ink is one of the most demanding parts of a DTF printing system. Over time, the white dampers inside your Mimaki TxF300 may need to be replaced to maintain proper ink circulation, consistent nozzle performance, and reliable print quality.
In the video below, the Blue Ridge Screen Products technical team walks through the complete white damper replacement process, from preparing the new dampers to resetting the replacement date and confirming the printer is operating correctly.
Watch the full video here:
When Should You Replace the White Dampers?
White dampers help regulate ink flow between the ink lines and the printhead. As they age, they may become less effective at maintaining consistent ink pressure and circulation.
A damper replacement may be needed when you experience issues such as:
- Inconsistent white ink output
- Missing nozzles that return after cleaning
- Air entering the white ink system
- Poor white ink circulation
- Visible damage or leakage around a damper
- A scheduled maintenance interval recommended by your technician
Damper replacement is a detailed maintenance procedure. If you are uncomfortable working near the printhead or ribbon cable connections, contact a qualified Mimaki technician.
Tools and Supplies You Will Need
Before beginning, prepare the following items:
- Four replacement white dampers
- Phillips screwdrivers
- A short Phillips screwdriver for tight areas
- A magnetized screwdriver, if available
- Cleaning swabs
- Disposable gloves
- Paper towels
- A nearby waste container
- Mimaki 03 maintenance liquid
- The pipette supplied with the maintenance liquid
- Ink Cleaning wipes
Give yourself plenty of room to work and keep additional paper towels nearby. White ink may drain from the old dampers as the ink lines are transferred.
Step 1: Prepare the New White Dampers
Remove the four new dampers from their packaging.
Avoid touching the cellophane membrane on the sides of the dampers. Handle each damper only by its narrow plastic edges. Touching or pressing the membrane may damage the component.
Remove the original white top from each new damper and replace it with the white top supplied in the damper package. If one of the small blue washers comes out during this process, carefully return it to the appropriate opening before installing the replacement top.
The clips on the replacement top should face downward.
Repeat this process for all four dampers.
Step 2: Lubricate the Damper Openings
Use the pipette to place one drop of 03 maintenance liquid into each damper opening.
This provides lubrication when the ink tubes are inserted into the new dampers and when the dampers are installed onto the printhead.
Use only a small amount. Once the dampers are prepared, close the maintenance liquid container securely.
Step 3: Prepare the Printer
Turn the printer on.
Remove the screws from the left and right sides of the printer’s front cover. The upper-left screw underneath the cartridges may require a shorter screwdriver.
Lift the cover and remove it from the printer.
Use the printer controls to advance the film until it covers the front heater. This protects the heater from white ink during the replacement process.
Enter Maintenance, followed by Station Maintenance, to release the carriage. Once the carriage moves out, carefully move it a few additional inches toward the center of the film.
Remove the printhead cover.
Step 4: Protect the Printhead and Electronics
This is one of the most important parts of the procedure.
The clear protective sheathing near the printhead covers the ribbon cable connections. White ink must not enter this area. Ink contamination around the ribbon cables can damage the printhead.
Use paper towels to protect:
- The ribbon cable connection area
- The cable located in front of the printhead
- The color printhead
- The film-detection photo eye
- The area directly beneath and in front of the white dampers
Place enough absorbent material below the dampers to catch the ink that drains from them.
Step 5: Remove the Old Dampers
Put on disposable gloves.
Begin with the far-left white damper.
Pinch the front and back of the damper and gently rock it forward and backward while pulling upward. Continue slowly until the damper releases from the printhead.
Always point the bottom of the damper away from the printhead. Once the damper is removed, white ink may begin draining from it.
Remove the remaining three dampers together from the right side. Loosening and lifting them as a group may make them easier to remove.
You may notice some white ink around the base of the printhead. A cleaning swab can be used to absorb pooled ink, but do not scrub or aggressively clean the printhead surface.
Step 6: Transfer the Ink Lines
Damper orientation is critical.
Each damper must be installed in the same direction as the original. In the video, the correct orientation is identified by:
- Two small white squares positioned on the right
- One larger circular feature positioned on the left
All four dampers must face the same direction.
Hold the new damper in your palm and the old damper toward your fingertips. Transfer one ink line at a time from the old damper to the matching position on the new damper.
Do not remove all of the lines at once. Moving one tube at a time reduces the chance of connecting a line to the wrong port.
The tubes should be seated to approximately the same depth as they were in the original damper. They do not need to be forced completely into the opening.
Continue this process from left to right until every ink line has been transferred.
Step 7: Install the New Dampers
Place the three right-side dampers into position together.
Once they are aligned, seat each damper individually by pinching the front and back and gently rocking it until it fits securely onto the printhead.
Install the far-left damper last.
Compare the height of all four dampers. They should sit level with one another when fully seated.
Lightly press the tops of the ink tube connections to confirm that none came loose during installation.
Step 8: Inspect and Clean the Work Area
Remove the used paper towels carefully.
Inspect the following areas for spilled white ink:
- Ribbon cable connections
- The clear protective sheathing
- The cable in front of the printhead
- The film-detection photo eye
- Ink tube connections
- The area surrounding the printhead
Clean any accessible spilled ink before reassembling the printer.
Step 9: Reinstall the Damper Bracket
Reinstall the bracket over the damper assembly.
Starting with the right side may make it easier to position the bracket around the cables on the left.
A magnetized screwdriver is helpful because the rear screws can be difficult to hold. Avoid dropping a screw behind the printhead, where it may be difficult to retrieve.
Once the bracket is properly aligned, tighten the screws securely without overtightening them.
Complete Station Maintenance from the printer controls and clean any white ink from the film.
Step 10: Reset the White Damper Replacement Date
Turn the printer off.
To enter service mode, press and hold Function 1, Function 3, and the Power button at the same time. Continue holding the function buttons until the firmware version appears and the printer beeps.
After the printer completes its startup process:
- Open the menu.
- Navigate to the adjustment or service settings.
- Select Replacement Date.
- Select White Damper Replacement.
- Choose Replace All.
- Confirm the selection.
The displayed date may show the following day rather than the current day.
Back out of the menu and turn the printer off. This resets the damper replacement information so the printer can adjust its white ink circulation behavior for the new components.
Step 11: Fill the New Dampers With White Ink
Turn the printer back on normally.
Navigate to:
Menu → Maintenance → Fill Up Ink
Select the normal fill setting and choose the white printhead only. Do not perform the fill on the color printhead.
Execute the ink fill.
As the process runs, you should be able to see white ink entering and filling the new dampers. Inspect the tube connections for any signs of leakage.
Step 12: Perform an Air Purge
After the ink fill is complete, navigate to:
Maintenance → White Maintenance → Air Purge
The air purge helps remove air that may remain in the dampers and white ink system after installation.
Once the purge is complete, perform a nozzle test.
A clean nozzle test indicates that the dampers are properly installed and the white ink system is functioning normally. If nozzles are still missing, perform another air purge and test again.
Step 13: Reassemble the Printer
After confirming a clean nozzle test:
- Reinstall the printhead cover.
- Reinstall the printer’s front cover.
- Replace and tighten the exterior screws.
The upper-left cover screw only needs to be snug or finger-tight enough to hold the cover securely.
Final Thoughts
Replacing the white dampers on a Mimaki TxF300 requires patience, careful organization, and close attention around the printhead electronics.
The most important things to remember are:
- Never touch the damper’s cellophane membrane.
- Keep every new damper in the correct orientation.
- Transfer only one ink tube at a time.
- Protect the ribbon cable connections from white ink.
- Reset the replacement date after installation.
- Perform an ink fill, air purge, and nozzle test before returning to production.
Need help with your Mimaki TxF300?
Blue Ridge Screen Products provides Mimaki parts, maintenance supplies, technical support, and printer service. Contact our team to speak with an experienced technician or to order replacement white dampers for your printer.
