Updated: Nov 6, 2019
If half of all printer service calls are for jams, then fully one-third of them are for image problems. Actually, image problems are even more extensive than that, but many are handled without the aid of a technician.
It's no secret that most image problems are caused by cartridges, either new or refilled, and that many customers have learned to try changing the cartridge before calling the technician. With that in mind, the number of machine failures caused by image problems may equal those caused by jams.
It is important to note that even if the imaging system is working perfectly, image problems will still occur. Because paper path problems often cause imaging problems, it's important to develop a system for classifying and troubleshooting image problems
THE TONER CARTRIDGE
With virtually any image problem, it is usually a good idea to try another cartridge Often, the "signature" of the original complaint will fail to appear with the second cartridge, indicating cartridge failure as the source of the problem. This can be true, even if the second cartridge is unacceptable as well (it will likely be unacceptable in a different way). With that in mind, let's take a look at cartridges, how they work, and what can go wrong with them.
Toner Cartridge Parts Printers without one-piece cartridges frequently divide the cartridge's functions as two assemblies -a Developer Unit with the toner supply, and a Scavenger Unit, which carries the Organic Photoconductor (OPC) and gathers and stores the waste accounting for a rising share of the market, or can be, done to each of these parts as So toner. Refilled toners are once more we'll take some time to discuss what is, prepared for reassembly.
The Developer Unit The Developer Unit is also equipped with a method for delivering the toner to the OPC. The Developer Roller, or "Mag" Roller, consists of a permanent magnet core, surrounded by a thin-walled aluminum sleeve.
Toner manufacturers reacted to the unique properties of the new carbon-coated sleeves, new formulations produced much denser prints and have ever since. Today, it is impossible to remanufacture a cartridge that will duplicate the electrostatic balance of an OEM cartridge. In most cases, they can get pretty close.
Contacts, seals, bushings and a doctor blade round out the parts list for the Developer Unit. Most Developer Units, both in new cartridges and refills, rarely have problems. Although things can go wrong poorly gapped, toner can clump and inhibit development, deoxidizing compounds cal foul the bushings a Doctor Blade can be improper usually, the developer can be relied upon to operate properly.
Toner remanufactures, wanting to prevent surface oxidation from causing ghosting, often treat the Mag Roller Sleeves with special compounds. Should the refiller attempt to treat the sleeves while they are still mounted on the developer, he runs the risk of fouling the bushings, Rather than cause jams or poor mechanics, these chemicals within the bushings will produce distorted images everything from fisheyes to gray background
Developer Unit Toner has a ferrous component that causes it to adhere to the Developer Roller, which has a permanent magnet core. The toner is held to he proper depth by the Doctor Blade that is set a measure distance from the face of the rollers sleeve.
The Drum Unit
Most of the critical electrical activity happens within the Drum Unit. It contains the Organic Photoconductor (OPC), Primary Corona Assembly, Wiper Blade, Cleaning Blade, and Waste Bin. Cartridge problems generally start and finish here.
Drum Unit. The image is formed on the OPC (Organic Photoconductor), first, electrostatically, then (after development) in reverse with the former. Some of the problems with recharged cartridges are caused by improper handling of the disassembled drum units.
The OPC is the most vulnerable item in the entire toner cartridge. Unfortunately, there has been a practice of "use-until-failure" in the toner in the remanufacturing industry, a practice that has persisted until the present.
Competent remanufactures routinely replace components on schedule, others continue to use everything until it fails., Unfortunately, the failure is generally in a customer's machine.
While there are methods for salvaging the drum recoating and reusing absolutely not reusable in the condition attained after the first cycle Third-party "Super-drums" is in many ways technically superior to the OEM drums. Their polycarbonate coating is identical to the sort of coatings used for high-capacity copiers. It is harder and has a much longer service life The primary concern for service performance has a lot to do with why they are called "Super." They print darker, using the same toner than the OEM drums op
The only explanation for this must be the ability to accept and hold a charge. During the conditioning stage of image formation, the Primary Corona Wire has a -6,000 volt DC charge sent through it. Because there is no return, no complete circuit, the uninsulated wire conducts negative high-voltage electricity.
The result is ionization of the air around the wire. The ionized air moves outward through the varistor grid on the cover of the assembly, then brushes against e OPC, charging it to between -600 and-690 volts DC, the varistor grid supposedly bleeding off excessive charges.
There is nothing sacred about that number; it's just what it happens to be for that particular OPC coating. My belief is that the Super-drums do, in fact, receive a greater charge from the Ionized air and that the contrast in charge to discharged area promotes a darker print. (This is not the way the machine density control makes prints darker. The density adjustment controls the AC Bias that drives the toner towards the OPC from the Developer.)