HP LaserJet 2840 all in one printer prints blank pages - no matter if a word or excel doc..printer goes through but page comes out blank.

The solenoid that controls the carousel movement is sticking throwing off carousel home position. The laser scanner beams are actually hitting the black plastic carousel instead of the cartridge drums therefore getting blank pages with no error codes. This was an early color machine that didn't have the error code 59.xx (transfer belt movement errors) that is currently in the error code list for newer HP color printers. This solenoid is not that difficult to get to. Just remove the sticky substance (self explanatory once you get to it). When I clean these I used blue painter tape on the sticky areas when reassembling which works for me, but you can do whatever...just get the sticky off!!

Not to sound like a smart aleck...do you have enough toner in it? Can you print a test page? Sounds like a toner issue to me.