What Breaks Most Often in Printers
Looking at a printer from the outside, we see only a box. However, inside, it is a precision chemical-mechanical factory. To understand why the equipment refuses to cooperate, we need to break it down into its components, dividing the world of printing into two main technologies: “wet” (inkjet) and “hot” (laser).
Table of contents
Inkjet Printers, or Precision Hydraulics
The inside of an inkjet printer resembles an automated gantry crane. The heart of the system is the carriage, which moves left and right along a metal rail. It houses the ink cartridges and the most important component, the printhead.
The printhead is a component made with jeweler’s precision. It contains thousands of microscopic nozzles, thinner than a human hair. Its most common failure is drying out. Ink is a liquid that, after the water evaporates, turns into a thick sludge or a solid deposit. If you do not print for several weeks, ink residue in the nozzles crystallizes, creating blockages. This manifests as “banding” (white lines on the printout) or the complete absence of one color. In CISS systems (with refillable ink), there is also the problem of air in the tubes: when air gets into the ink supply lines, the pressure drops and the printhead stops ejecting ink, even though the reservoirs are full.
Less attention is paid to another key component, namely the encoder strip. This is the transparent plastic strip that runs across the entire width of the printer, just behind the carriage. It has thousands of microscopic lines printed on it. The printer “reads” them to know exactly which millimeter the printhead is at. Typical failure: When the strip gets dirty with grease or ink (which happens after years of operation), the printer “gets lost.” The result? The printout is “misaligned,” vertical lines are jagged, or the carriage forcefully crashes into the wall of the housing, producing a terrifying noise.
At the bottom of the printer lies its dark secret: the absorber (also known as the “diaper”). Every time the printer is turned on and every time the print head is cleaned, ink is used that does not end up on paper but is instead “spat out” into the machine. It goes directly onto these sponges. Typical failure: When the sponge becomes 100% saturated, the electronics lock the printer and display a service error message. In cheaper models, this means the end of the device’s life; in more expensive ones, the sponge cartridge is replaced.
Open HP 845c printer – Two ink cartridges: color on the left, black on the right.
How to Prevent Printhead Nozzles from Drying Out?
Fortunately, dried-out print head nozzles are not a death sentence for the printer. If the print head dries out, we have a few options to choose from:
- Automatic cleaning – most printers have a printhead cleaning function in the menu (it uses quite a lot of ink, but often helps)
- Manual cleaning – the printhead can be gently rinsed with warm distilled water or a special cleaning solution
- Soaking – in difficult cases, the printhead can be soaked in cleaning solution for several hours
photo: André Karwath
How to prevent:
- Print at least once a week – one test page is enough to prevent the ink from drying out
- Most printers automatically perform a mini-cleaning every few days (you can hear characteristic sounds at that time)
- Do not unplug the printer – it needs power for automatic maintenance
Head type matters:
- Cartridge-based print head (HP, Canon) – you replace it with every ink cartridge, so there are fewer problems, but the cartridge itself is much more expensive
- Permanent print head (Epson) – it is permanently installed in the printer, so it pays to take better care of it
Laser Printers
Laser printers are generally more durable than their inkjet counterparts. However, this sense of sturdiness often lulls users into a false sense of security. In reality, beneath the hard plastic casing lies a precision mechanism combining advanced optics, high temperatures, and chemistry. Key components—the photosensitive drum, fuser, and transfer belt—are surprisingly sensitive to our mistakes, and their failure can turn a functioning device into electronic waste. Keeping a printer in good condition does not require an engineering degree, but rather an understanding of what happens inside it.
The Heart of the Device: Photosensitive Drum (OPC)
The most important component of any laser printer is the photosensitive drum. It is that distinctive, shiny green or blue tube that we see when replacing the cartridge. It serves as a kind of negative of the printed page—the laser “draws” an image on it using an electrical charge, attracting toner. However, the drum is extremely delicate. The biggest mistake users make is touching its surface with their fingers; natural oils from the skin change the roller’s electrical properties, resulting in permanent spots on every subsequent printout. The drum also hates sunlight—leaving a removed cartridge on a desk in direct sunlight for even fifteen minutes can permanently “overexpose” it, which appears as pale bands on the pages.
However, the absolute drum killers are staples. We often put recycled paper into the feeder (e.g. to print on the reverse side of unnecessary documents), forgetting to remove the metal elements. A single overlooked staple will scratch the drum on the first rotation, and each scratch will thereafter be visible on the printout as a dot or line repeating every few centimetres. This damage cannot be repaired; it requires replacement of the entire module.
Hot Topic: Fuser and Paper
Another critical stage is fusing. When toner reaches the paper, it is still a loose powder that can be blown away. Only in the fuser (commonly called the “oven”), at a temperature close to 200°C, is it permanently pressed into the structure of the sheet. To avoid damaging this unit, you should steer clear of the cheapest, dusty paper. Cellulose dust settles on the heating rollers and burns, damaging the delicate Teflon coating, which leads to so-called “ghosting” (a fragment of text from the top of the page is faintly reproduced at the bottom).
Even more dangerous are unsuitable self-adhesive labels. Inserting ordinary office stickers into a laser printer instead of those designed for laser printing (resistant to high temperatures) ends in disaster. Ordinary adhesive melts under the heat and permanently coats the fuser rollers. Such a failure is usually uneconomical to repair, as the cost of replacing the fuser often approaches the value of the entire printer.
Toner: More Than Just Black Powder
We often forget that the most important maintenance measure is the choice of toner itself. Contrary to popular belief, toner is not just a coloring agent. In the case of original cartridges and high-quality compatible products, this powder is a complex chemical mixture containing wax, polymers, and often microscopic ceramic particles. They act as a “lubricant” for the mechanism—they polish the drum, preventing it from becoming dull, and lubricate the fuser film so that it slides smoothly over the paper.
This brings us to an economic dilemma: is it worth buying original cartridges? Original toner cartridges are safe, but absurdly expensive. On the other hand, the cheapest “no-name” substitutes (sold in plain white boxes for next to nothing) are often nothing more than ordinary soot without any performance-enhancing additives. Such powder acts like sandpaper—it accelerates drum wear and increases friction in the fuser unit, cutting the printer’s lifespan in half.
The golden mean is to use branded alternatives (so-called premium alternatives) or remanufactured toners. Products from brands such as ActiveJet, Asarto, and Katun are more expensive than the cheapest Chinese products, but their chemical composition is similar to that of the original, and the cartridges are made of better-quality plastic. In the case of remanufacturing, professional companies take a used, original cartridge (which fits the printer perfectly), clean it, and fill it with high-quality powder. This solution ensures mechanical and chemical safety at a fraction of the original price.
The Mechanics of Paper: Why Does the Printer “Lie” About a Paper Jam?
Regardless of the technology, the most common reason for service visits is not the electronics, but the pickup rollers. They are made of rubber with a rough texture (like a car tire) to grip the sheet. Over time, this rubber oxidizes, hardens, and becomes as slippery as plastic, or gets coated with paper dust. A typical failure looks something like this: the printer spins the rollers and tries to pick up the paper, but cannot, and displays “Out of paper” or “Paper jam,” even though there is paper in the tray. All it takes is cleaning the rollers with a rubber rejuvenator or replacing them.
The second culprit is sensors (flags). There are small plastic levers in the paper path. A moving sheet pushes them, sending a signal to the computer: “I’m here.” Sometimes a piece of torn paper or clumps of dust block such a flag in the “pressed” position. The printer “thinks” there is paper inside even though there isn’t, and refuses to operate, reporting a jam (Phantom Paper Jam).
Summary: What Breaks First?
- In inkjet printers: The print head (due to lack of use) and the paper feed mechanism (due to dust).
- In laser printers: Pickup rollers (due to age) and the photosensitive drum (due to wear).
- In both: Our patience when we try to connect them to a new Wi-Fi router.