Why won't my brother mfc 7840 connect to pc

SOURCE: Black lines in copies and fax's Brother MFC 7420

If the black lines comes when using the ADF (top feeder), try to see if you get the same problem when using the scanner glass or receiving faxes. If you don't, you simply have to clean the glass strip to the left of the a4 sized scanner glass. Wipe it with a dry cloth piece, no paper and no water/alcohol. If you see some dirt there that you're unable to simply wipe off, try to use a cotton wool to "rub" it off.

Richard Eisenman

• 10 Answers
• Posted on Nov 21, 2009

SOURCE: Brother MFC 8220 all-in-one fax prints with a vertical line

First guess is you have a bit of dirt (often white-out from people scanning corrected paper that's not quite dry) stuck on the fax scan window. This should be described pretty well in your user manual (which you can download online from brother.com).

Its also possible that there is dirt (typically loose toner) on the laser scan window (there's a laser that shines through it to get the image pattern on the drum). That window is often along the bottom of the unit under the drum/cartridge (take the cartridge out and look). The Brother manual I've seen seems to ignore this possibility.

Print streaks DO NOT mean cartridge drum replacement in many cases !! On brother Intellifax or MFC or other laser copier/printer/fax, keep in mind that either the fax/copy scan window OR the laser scan window can get dirty. If the fax scan window is dirty, you see streaks on outgoing faxes and copies (but NOT incoming faxes). If the laser scan window is dirty, you see streaks on all prints (copies, faxes, print-from-computer).

Note also that when transporting/moving some laser copier with the toner cartridge inside, the toner can get out and make a big mess inside (including getting the laser scan window dirty). An air compressor can be usefull to blow it out. And sometimes using alcohol to clean is a BAD idea (maybe incompatible with plastic and rubber parts). A damp rag is probably fine.

SOURCE: how to install LAN Brother MFC-5840CN on Windows 7

You cannot use the full driver and software package now. BUT:
Printing is possible, scanning and FAX is not possible at the moment. You download the Vista driver (x32 or x64) from the official Brother site and install it with the Printer Wizard in Windows 7.

SOURCE: brother mfc-215c unable to clean?

I have the same problem my printer (a MFC-215C) is unable to clean and when I press Menu/set I do not have "Black print"? So what do I do now?????? HELP... Thanks Nathalie

SOURCE: mfc-7840 brother printer is saying

You need to replace the drum unit,the drum unit is the case in which lies the toner.Try to reset the drum unit like that:

1.the printer is online
2.open the cover
3.push a button clear or check on the panel with the cover open and then push reset drum

If i have been useful please give me a vote :).Thanks