Which ink/toner does the Brother HL-L5100DN use?

The Brother HL-L5100DN is a workgroup mono laser and takes the TN-820 toner family. Three sizes fit it: the standard TN-820, the high-yield TN-850 and the extra-high-yield TN-880. The drum is a separate DR-820 rated at about 30000 pages, which makes a drum change a far rarer event than a toner change on this machine.

This is a printer where buying the bigger cartridge pays back fast. The TN-820 is rated at about 3000 pages for around $80, near 2.7 cents a page. The TN-850 does about 8000 pages for around $110, or about 1.4 cents. The TN-880 stretches to about 12000 pages for around $160, roughly 1.3 cents. Moving off the standard cartridge roughly halves your running cost. The step from the TN-850 up to the TN-880 barely moves cost per page, so take it for the convenience of swapping cartridges less often rather than for the money.

Brother does not use firmware to block non-OEM toner, and compatible or remanufactured cartridges in all three yields work here. The snag is the same page counter the rest of the Brother mono range uses. The machine counts pages rather than measuring what is left in the cartridge, and genuine toners trip a reset lever on cover close that many refills lack, so a brand new compatible can still show a replace toner message. Continue mode lets you keep printing past the warning until print quality genuinely drops.

On a printer this size the maintenance that matters is the drum rather than the toner. A mark that repeats down the page at a regular interval is a drum defect, not a toner fault. A page that comes out faint or grey all over usually means the corona wire needs cleaning, which is the green slider inside the drum unit run gently from side to side a few times. Toner Low is a prediction from the page counter, so carry on printing until quality actually falls off instead of swapping on the message.