Printing, copying, incomming fax is ok but in outgoing fax the whole document is black print to other fax machine

make sure the property settings for the fax are not on the Microsoft printer make sure it is set to the local usb printer

Check your incoming line and settings or try to reinstall the drivers. Also, check the user manual for HP Officejet Pro L7780

Install software
Make sure all cables plugged: phone cable, USB cable to computer

Send fax from computer:
- print your document to printer HP .... FAX

Send "traditional" fax:
- put your document into scanner input
- type phone number on HP Officejet keyboard
- push button "Send"

If your HP Officejet if connected to phone line, it reseiving faxes automatically.

Hope this helps

If it is just from incoming faxes and not from anything you print/copy then it is the sender's fax machine that is dirty. If everything you do has that line, try cleaning the scanner glass and corona wire.

On this machine for black copies, the areas to check are the HVPS, The ROS, or the Print engin Board.
Most likely on this machine the HVPS can be the problem, then the ROS, then the printe engine board.
The definitions are the scanner platen is under the document feeder, the ROS is the actual laser scanner.
Taking this machine apart several times, one can also check the ground straps to the copy cartridge to make sure they are connecting to copy cartridge when it is inserted into the machine.

Your image scanner is bad. Try making a copy....if it comes out black but your incoming faxes are fine then your image scanner is bad. You can also print a report from the machine and it should come out fine.
The image scanner is the part that scans your originals before faxing them out or making a copy. There is a light bar that lights up when scanning. Either that light bar(l.e.d. array) has gone bad or the scanner itself is bad. If this is the case it is probably going to cost more to fix than the machine is worth. You could buy a new machine for what it would cost to fix.
Good Luck and Thank You for using Fixya.

hp laserjet is not a fax.It is only a printer.

Hello sir; Either drum cleaning blade or drum cartridge needto replace.

do a quick check on 2 things.
- Copy a document(put a printed page on document feeder and press Copy button) , has the Copy come ok? if copy is also blank that means toner/ink problem, needs to be replaced.

- check with your Fax receive Print settings. is any setting of econo mode/ contrast/brightness Off the track? If found any of such issue then Reset it or put it on average (middle).

Hope this will put your Brother on the track

just copy a paper if copy is black ur scanner is dirty or dead .first clean scanner with tissue other wise change it.if copy is ok result not black that is due to telephone line.by mian jee