Printers have sure come a long way. I fondly remember by Commodore MPS-801 dot matrix printer with 42 pixels — total — for each letter. It used continuous fanfold paper and only printed in one direction.
Fast forward thirty years. (Yikes!) Now our current printer does full color, two-sided, in pretty much any font I want. The Brother HL-4070CDW printer cost us about the same, in current dollars, as my MPS-801 did back in the mid 1980s.
I still think the cost of ownership for our Brother printer is less, but the toner cartridges are expensive. A full set of high-capacity cartridges set us back over $350 — about as much as the printer itself cost us.
When laser printers attack
To make matters worse, when the “replace toner cartridge” indicator went on for one of the colors, the display would go red and it would refuse to print anything. We had no choice but to replace the cartridge, after which it usually worked.
Except the last time it didn't work. We put in a fresh yellow toner cartridge, and it smiled at us and told us to replace the yellow toner cartridge. Now, I'm not always the sharpest tack in the box, but I knew that the solution was not to buy another yellow toner cartridge.
So we went to Google and it led us first to Brother's help page on the subject. We tried everything there. We even had another drum unit on standby because that indicator had been on for about six months, and replaced it when the rest of the steps on the help page didn't resolve the problem.
At this point, I wondered if the indicator was just based on number of printed pages, rather than some ink sensing mechanism that indicated that the cartridge was empty. If that were the case, then whatever inserting the new cartridge does to reset the counter wasn't working, and I might just be able to reset the counter manually.
It turns out that was the answer. Someone paid $28 for the answer here, but I took advantage of it for free. 🙂 We entered service mode with a special incantation, and reset the counter. After that, it worked.
The lesson we learned is this: You don't necessarily trust the printer when it tells you to replace the toner cartridge, especially if the print quality isn't horrible. Now, I'm not saying that Brother programmed their printers to tell you to replace the cartridges when they're 3/4 full, but it would make sense that they program it to tell you to replace them before the print quality went down.
If the replace toner cartridge indicator comes on as a result of page count, it's just an estimate. It's not based on how much toner is left in the cartridge.
Try to use up all of the toner before replacing the cartridge! If the printer is telling you to replace it when it's not empty, figure out how to fool it. It's just a machine.