Answer to your Frequently Asked Question:

Printer Friendly
Description of Problem 100000028823

The printed pages have black vertical lines or streaks. How can I improve the print quality?

Description of Solution 200000036977

Brother strongly recommends that customers use only genuine Brother drum units and/or toner cartridges. Each Brother laser printer is designed to work at pre-set temperatures that are matched exactly to each of our individual toner formulations.  Each individual component is designed to work with the other to ensure quality and reliability. Using non-Brother supplies may affect the hardware performance, print quality, and machine reliability. The Brother limited warranty does not apply to any problem that is caused by the use of third party drum units, toner cartridges, or toner.



1. Print the Printer Settings pages by pressing the OK key 3 times.


- If no black vertical lines appear, the issue appears to be resolved. 


- If black vertical lines appear on the Printer Settings page, continue to the next step.


2.  Perform a manual cleaning of the drum surface:


a. Open the front cover.




b. Take out the drum unit and toner cartridge assembly by pulling on the handle in the middle of the drum unit and toner cartridge assembly.



NOTE: We recommend that you place the drum unit and toner cartridge assembly on a piece of paper in case you accidentally spill or scatter toner.


c. Push down the green lock lever on the right side of the drum unit and toner cartridge assembly and then lift the toner cartridge out of the drum unit. 




NOTE: Handle the toner cartridge carefully. If toner scatters on your hands or clothes, immediately wash it off with cold water.


d. Inside the drum unit is a roller. Clean the roller by gently wiping the entire surface with a lint free cloth or cotton swab lightly moistened with isopropyl alcohol (91% strength alcohol is preferred, but 70 - 75% strength alcohol is also acceptable).  You can also use an alcohol swab, such as a medical alcohol pad or wipe, which can be found in a first aid kit.  Use the white gear on the far left side to turn the roller and ensure you clean the entire surface. 


As a precaution please note: Isopropyl alcohol is flammable and should be kept away from fire or flame. 



e. If physical damage, such as scratches, nicks, or gashes in the surface of the drum, is found when inspecting the drum, there is no need to continue cleaning since it will not resolve the issue.  The drum (DR720) needs to be replaced.


f. Before continuing further, allow the alcohol to evaporate or dry off the drum surface.


g. Once the drum surface is dry, clean the primary corona wire inside the drum unit by gently sliding the green tab located at the top of the drum unit from left to right and back several times. Be sure to return the green tab to the home position (1).





h. Reinstall the toner into the drum (be sure it clicks into place). If you put it in properly, the green lock lever will lift automatically. 





i. Reinstall the drum and toner assembly into the machine and close the front cover, pressing firmly on each side until the cover clicks into place.





3. Print 10 to 15 blank pages from the computer to further clean any remaining debris left on the drum surface.


4. Print the Printer Settings pages by pressing the OK key 3 times.


- If no black vertical lines appear, the issue is resolved.


- If black vertical lines still appear on the Printer Settings pages, a second manual drum cleaning may be needed.  Repeat STEPS 2 - 4


-  If there are still black vertical lines after doing two (2) manual drum cleanings, the toner (TN720, TN750, or TN780) needs to be replaced.


5.  If the vertical lines continue after replacing the toner, the drum unit (DR720) will need to be replaced.






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