20 Most Recent Brother MFC 7840W Printer - Page 7 Questions & Answers

Replace the drum unit.
Follow the procedure below to replace the drum unit.

The Brother machine has separate consumables the toner cartridge and the drum unit. Verify you replace only the drum unit and not the toner cartridge. If you want to know their difference, refer to "What is the difference between the toner cartridge and the drum unit?"

Caution Do NOT use flammable substances near the machine. Do NOT use any type of spray to clean the inside or outside of the machine. Doing this may cause a fire or electrical shock.
spray1.gif Caution
  • While removing the drum unit, handle it carefully because it may contain toner. If toner scatters on your hands or clothes, wipe or wash it off with cold water at once.
  • After you have just used the machine, some internal parts of the machine will be extremely hot. When you open the front or back cover (back output tray) of the machine, DO NOT touch the shaded parts shown in the illustration. If you do this, you may get burned.
  1. Open the front cover.
  1. Slowly take out the drum unit and toner cartridge assembly.
replacedrum_02.gif Caution
  • We recommend that you put the used drum unit and toner cartridge assembly on a clean, flat surface with a sheet of disposable paper or cloth underneath it in case you accidentally spill or scatter toner.
  • To prevent damage to the machine caused by static electricity, DO NOT touch the electrodes shown in the illustration.
  1. Push down the green lock lever and take the toner cartridge out of the drum unit.
Note Discard the used drum unit according to local regulations, keeping it separate from domestic waste. Be sure to seal up the used drum unit tightly in a suitable bag so that toner powder does not spill out of the unit. If you have questions, call your local waste disposal office.
  • Wait to unpack a new drum unit until immediately before you put it in the machine. Exposure to direct sunlight or room light may damage the drum unit.
  • To avoid print quality problems, DO NOT touch the shaded parts shown in the illustrations.
  1. Unpack the new drum unit.

  2. Put the toner cartridge firmly into the new drum unit you hear it lock into place. If you put the cartridge in properly, the green lock lever will lift automatically.
Caution Make sure that you put in the toner cartridge properly or it may separate from the drum unit.
  1. Clean the primary corona wire inside the drum unit by gently sliding the green tab from right to left and left to right several times.
Caution Be sure to return the green tab to the home position (1). If you do not, printed pages may have a vertical stripe.
  1. Put the new drum unit and toner cartridge assembly in the machine.
  1. Press Clear/Back.

    For MFC users:
    To confirm you are installing a new drum, press 1.

    For DCP users:
    To confirm you are installing a new drum, press the Up Arrow key.

  2. When the LCD shows Accepted, close the front cover.

Brother MFC... | Answered on Mar 05, 2012

Try disconnecting the printer completely from power and from the PC.
Leave it as such for one hour.
Connect the printer again.
Check the connections and make sure its well connected.

Brother MFC... | Answered on Feb 28, 2012

To reset MFC-7840W drum count use the following steps.

1. open the front cover (leave open).
2. Press clear/back.
3. Then confirm the new drum install by pressing 1.
4. The display will indicate accepted.
5. Then close the front cover.

This should be done each time the drum unit is replaced.

Brother MFC... | Answered on Feb 02, 2012

As noted from a previous poster, this one works!

I have a brother mfc 7840w

I first used the electrical tape trick and that worked for a while. Then got the toner low message again. I then tried the *00 trick, which works as follows:

1. lift lid and open front cover
2. press clear/back. "Replace Drum?" will appear on the screen.
3. Press "*00" it will then read accepted and the toner low error (End of Toner Life) should go away.
4. close it all up and your done.

Thanks for all your help guys.

Brother MFC... | Answered on Jan 28, 2012

It is common, mainly because the MFC connection is lost to your PC. Are you able to print or scan from another wireless PC that you have? If yes, contact your network admin or router oem. If no, reset network card. Run the Setup Wireless Wizard. Make sure you have router info such as SSID, Network Security Key, Authentication Method (Open, Shared, WPA/WPA2-PSK), Encryption (None, WEP, AES, TKIP). Enter those info, it must be CASE SENSITIVE. Just in case you dont know your router info, contact your router oem.
For Advanced Users.1. Click your Wireless Icon at Task Tray2. Right-Click your Wireless Network Name3. Select Properties4. Go to Wireless Security Settings5. Take note of the settings that you have there and enter it again on your MFC
Goodluck! If you still need more assistance. Call us 1-877-Brother. :)

Brother MFC... | Answered on Jan 09, 2012

First...do you have or previously other printers on your system or network.You need to make sure that the system recognizes this printer as the default printer.If it was me...I would reinstall all of the software to eliminate any issues and make to make this your default printer....If you are running windows Xp..once you reinstall the software....go to the start button....the my computer...control panel....printers and faxes..this should show all printers in the system...if your printer has a check mark beside it...this the default..if if is not checked...right click on the printer and make it the default.You should not get the error message again...I hope this was helpful.....

Brother MFC... | Answered on Dec 14, 2011

The first thing that I would try multiple people to ask them to fax you.Sometimes the 2 machines don't "sync".This is a toll free fax test number that I always use to check my machines..1-888-473-2963.Just write the words "FAX TEST" in large letters on a blank sheet of paper..fax it to that number...leave the line open...you should get a fax back in about a minute.If you get a fax back...your machine is fine...let me know if this was helpful....thanks.

Brother MFC... | Answered on Dec 14, 2011

You need to open the front cover ( where the drum and toner is installed), then press the clear/back button, then will ask if you replaced the drum, chose one for yes, it will says accepted, then close the cover.

Brother MFC... | Answered on Nov 17, 2011

Had the same thing happen. Unplugged the power on the printer and plugged it back in. No problems now.

Brother MFC... | Answered on Oct 10, 2011

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