Laser Printers

Brother DR-400: The Role of a Drum Unit on Laser Printer

What is a drum unit? Otherwise called the Photoconductive Unit (PCU) is a laser printer component containing the corona wire or separate charge roller and imaging drum. This consumable is purposely responsible for transferring toner to paper. The laser printer puts toner onto the photosensitive drum (roller) and then prints images and letters by setting toner to paper through heat and pressure. The drum unit can either be incorporated with the toner cartridges/s or a separate unit like the Brother DR-400.

How does it work? The Brother DR-400 drum unit for instance rotates to complete several tasks.

  1. A positive charge from the corona wire allows tiny laser beams to pick up or paint the image to the drum.
  2. As the positive charge paints the text, the negative charge it produces creates a reversed or negative background.
  3. The drum unit then attracts the toner through electrostatic. And as the paper passes through the PCU, the toner imprints on the paper with the image it has painted.
  4. The paper then passes through the fuser unit where the toner is melted and finally creates the final output.

When to replace the drum unit? A drum unit is a consumable; therefore, it depletes overtime. There are mainly two ways to know when the PCU needs replacing.

  1. An alert or message will appear on the LCD display indicating that the toner level is low along with a beeping sound.
  2. One of the most obvious indications that a drum unit needs replacing is when the printout quality begins to deteriorate or is defective.

Some users take no heed of the warning sign on the display and keep running the printer with an almost empty or a low toner level. This is not a good practice because it can damage the printer head and could eventually break the machine. It is fully understandable that the users would want to prolong the inevitable because a genuine drum unit is costly. Yet, there are cheaper but dependable options like the remanufactured Brother DR-400 to avoid damaging the printer.

You Might Also Like


  • Reply
    click here
    July 14, 2017 at 1:32 pm

    I am genuinely glad to read this weblog posts which consists of tons of useful facts, thanks for providing such information.

  • Reply
    fifa 18
    July 21, 2017 at 7:54 pm

    I was able to find good advice from your articles.

  • Reply
    click here
    July 27, 2017 at 1:17 am

    Your mode of describing all in this post is actually nice, every one be able to simply be aware of it, Thanks a lot.

  • Reply
    September 4, 2019 at 6:27 am

    Thank you for this information. Glad i got some other hints on how do we know when a drum unit will be replaced. Also i have additional info’s aside from the given signs to replace the drum unit is the prints will get blur or having some black spots, poor print quality is characterized by faded text and images. I am sure the unit will be save long lasting printer.

  • Reply
    September 17, 2019 at 7:41 am

    This was very helpful thank you so much, I thought up until today that a drum was a larger capacity unit that came with the stated capacity of toner. Not just the above information but i also want to know the troubleshooting and maintenance schedule of drum unit, i am looking forward for more good info’s to it. Thanks

  • Reply
    October 9, 2019 at 7:47 am

    Very nice read, without a drum unit, the toner powder in the cartridge cannot be transferred onto the page. The two parts work together to create a print! You can’t have one without the other and expect the printer to work properly.

  • Reply
    October 29, 2019 at 8:04 am

    Very well written, answers all of my questions as best one could. I wish life was not so complicated, though.

  • Leave a Reply