MFC 7820n 'close back door error' - Brother MFC-7820N All-In-One Laser Printer

Turn off your printer.
Open the back cover
Slam it shut - not hard enough to break it
Turn on printer
If you still have error, you most likely have a defective sensor for the back cover and will take a professional repair.

I found the following post on another site. It appears to work. If you want to reset your Brother MFC 7820N machine so you no longer have the error message: Toner End of Life, do the following:

1. Open the front cover of the 7820N, that is, the cover that allows you to pull out the toner and drum, but don't pull out the drum/toner.
2. Push the button: Options (located on the left of the control pad).
3. Type: *00 on the keypad.

The Brother MFC 7820N should be reset and the Toner End of Life message should disappear. WARNING: This may void your warranty and ultimately damage your machine if you are reusing or refilling your cartridges, but you should already know that. Hope this helps.

Buy some pants.

I have fixed this problem on my 7820n printer by brother.

open the back door, then inside there will be a black colored other kind of like door that pulls back away from the roller. on this inner door is a black long thin plastic lever that runs from about the center of the inner door to the right. on the right end of it is a lever that slides along a curved increase on the right side wall. when both doors are closed this right end of the rod or lever moves up to close the gap between what is the sensor. this long thin plastic rod had snapped out of place and when i snapped it back in making sure the spring was correctly installed on the left end of it and the middle part of the rod slid correctly in its groove...the right end of the lever correctly closed the gap on the sensor (when both doors are closed) and the back door open error went away.

So that's how you really fix it!!!!

James Hilliard - Totally super awesome guy! hee hee

First Isolate whether it is the Side Door or their is a door on the rear make sure that isn't open.
What I would do is Physically open and re-close all doors again the tabs and sensor get sticky after awhile. If not you could have a BAD sensor door switch.

yes, error 74 points to toner empty. open front door, press "options" then "start" then "1" and "0". once shows accepted, close front door. make note of this as it very well may happen again.

hth,
razors

first check and make sure that the back diir sensor is in place next if the paper is not going all the way in to the fuser section, you will have to remove the fuser and take it apart and remove paper in it, the paper is probally holding down the fuser sensor in side of it good luck brother sr, tech

Had same problem. Closer inspection revealed bit of paper out of sight. Removed the toner cartridge and worked to free torn paper. Then restart. Hope it helps.

http://www.fixya.com/support/t150137-one_more_person_back_cover_open_problem

There is a little black lever in the middle that needs to be re inserted properly. (like a little black stick in the middle.  Needs to slide to the left or right.   See more of this one the site.   It solved it for me.