Brother printer saying back door open when it isn't. Where is sensor exactly?

SOURCE: Brother Laser Printer MFC-7420

Ok I fixed this problem. It has to do with Tension on the rod inside the back cover. Open the back cover and remove it. Then emove the black plastic piece by un hooking it on the left side and pull it down then toward you. You will see a rod attached to it that runs to the right. The right end of the rod has a lever that travels in a slot on the right side of the printer. There is a small spring on the rod. Here lies your problem. There has to be enough tension on this spring to activate a switch in the slot on the right side of the printer. Make sure the spring is installed properly. This is a low tension spring so nothing will come flying out when you remoe it and re install it properly. A piece of paper can dislodge this spring. When you get it apart you can quickly see how it should be put back in. E-mail me if you need further help [email protected]

SOURCE: I can't find the back door sensor on Brother MFC-7420

I have the answer. I just fixed mine. The sensor is not really on the door. You have to remove the door by openning it all the way and carefully sliding it out ( one of the pegs holding the door is hourglass shaped. This will slide out first. The other is round. You will see a black flap that covers a red drum. Pull the flap down carefully. There will be a six inch long rod it's about 1/8 of an inch in diameter. It extends from the middle of the flap all the way to the right side. This probably popped out of place. Make sure that it is all the way to the right as this is where the sensor is. There is a little spring on the bar on the left side. This should be straight up and down. if it is not, then you need to fiddle with the bar.
The trick was that the sensor is NOT on the door, but on this inner flap. When the door closes it pushes this flap agains the drum and the little bar activates the sensor.
Please do not applaud so loud, you are ambarrazing me!!! hehehe. Good luck!.

SOURCE: Printer won't work

What it really means is that another piece of paper is still stuck in the printer, closer to the back. Pull out the paper tray and open the back to look again.

SOURCE: brother all-in-one printer not working; error 'back door open'

Open the front cover and remove the drum and toner.

There should be a paperjam in the machine. It reads back cover open because the piece of paper is covering the sensor for the back cover.

SOURCE: Brother MFC 7420 printer says

hello there


try this remove the toner of the printer and put it back again and closed properly make sure door close and turn off the printer remove the power plug from the outlet and ppower cord from the printer and wait for some time and turn it back on.

thank