The most common toner cartridge failure is usually due to issues with the drum unit. The drum has a wiper blade which scrapes any excess toner off the surface as well as off the paper and Transfer Belt.
When the OPC Drum Unit and all of it's components are not in perfect condition then the print quality will be compromised. Below are many of the issues with toner and drum units and also what tell tale signs to look for on the printed page. A high quality generic toner cartridge should not show any of the defects discussed below, however often cheap and poorly made toners will display various defects due to poor manufacturing techniques. Once again we stress that if you are going to use non genuine toners make sure that you buy them from a reputable dealer.
Most Common OPC Drum failures
Perfectly straight and very thin vertical line running full length of page
Indicates a scratched drum generally caused from foreign matter or build up of toner on the Wiper Blade, which scratches a ring around the drum during rotation.
Dots that repeat evenly down the page
This indicates a chip in the drum surface referred to commonly as a “pinhole”. The distance between the dots is dependent on the circumference of the drum (generally 4 times). Some pinholes, on closer inspection, can be built up foreign matter which can be removed with a cotton bud and Iso-Propyl alcohol.
Dots that repeat evenly down the page accompanied by a horizontal band across the pageThe dots indicate a pinhole and the band across the page. Indicates a short against the PCR, which is due to the pinhole.
Smears of toner across the page which are equally separated verticallyCaused by light damaged drum coating (sunlight). The distance between the smears is dependent on the circumference of the drum, generally 4 times. Exposing the Drum to direct light for long periods of time damages the coating/film.
Thin lines across the page equally spacedCalculate the circumference of the drum and if the thin lines are the same distance apart as the Drums circumference then the Wiper Blade has marked the Drums coating. This generally occurs with periods of time where the wiper blade rests against the drum when at rest. Heat also can play a role in this.
Grey “tyre tracks” on right or left side of pageThis issue is also sometimes described as wind blown sand. It is caused by a worn out drum. It indicates that the drum coating or film is starting to wear thin.
Wiper Blade Failures
The next most common toner cartridge issue to occur would be due to an problem with the Wiper Blade. After the image is transferred from the Drum to the paper or Drum to the transfer Belt there will be residual waste toner on the Drums surface which needs to be cleaned before the next revolution of the Drum. The Wiper Blades job is to collect, clean and scrape any residual waste toner from the Drums surface, depositing it into the waste toner hopper.
Most Common wiper blade failures are
Thin line down the pageThis is caused by a cut or nick in the blade which fails to collect, clean and scrape toner from the drums surface effectively leaving a lined mark down the page. This can also be attributed to a worn blade.
Gray page with toner visible on drumThe Wiper Blade isn’t applying adequate pressure to the drum to successfully clean the residual toner from the drum, which then gets applied to the next revolution of print. This problem is often due to the Wiper Blade not being correctly fixed in place (not screwed down properly,incorrect sealing foam etc). It can also be caused by an old wiper blade which has stiffened overtime. A stiffened blade doesn’t apply enough pressure to the surface of the drum which in turn limits the collecting, cleaning and scraping capability of residual toner. An indicator of an aged Polyeurethane Wiper Blade is a yellowy tinge.
Poorly lubricated blade, seizing drum revolutionThe Wiper Blade constantly applies pressure to the Drum, if the blade is poorly lubricated it will stick to the drum and travel in the same direction. Once the Blade has flipped it will apply immense pressure to the drum often seizing it completely or requiring a fair amount of force to turn it. Generally this will be accompanied by a loud clicking noise from the printer, thankfully the printer has a clutch to prevent stripping of gears and further damage occurring. You will see some compatible colour cartridges using Yellow toner as a lubricant, the Yellow toner tends to be finer and smoother and works quite well as a form of powdered lubricant.
Magnetic Roller FailureThe Magnetic Sleeve is effectively a coated aluminium roller that transfers the toner from the supply chamber to the drum by use of magnetic attraction. To break it down the Magnetic Roller sleeve encases a Magnet in the same shape as the Magnetic Sleeve. There is an electrical contact at the end of the sleeve to which a charge is applied to amplify the magnetic attraction. The black conductive coating found on the Magnetic Sleeve is made of various conductive materials with the sole aim of carrying the toner. Most failures are usually due to scratches or excessive wear of the coating. Toner particles in general are abrasive, when combined with pressure from the doctor blade doctoring/pressing toner against the Magnetic Sleeve roller effectively causes wear to the coating. Some cartridges use a Developer Roller in place of a Magnetic Roller.
Most Common Magnetic Roller Failures
Light printA worn out magnetic roller is probably the main reason for a light printout to occur. There is a black conductive coating that wears off the sleeve over time. If the coating on the Magnetic Roller were to wear thin or completely through, you would be able to visually sight the black conductive coating turn pale (wearing thin) or even revealing the aluminium tubing underneath. This type of failure will show up more on solid black areas and grey scales. Normal text wouldn’t normally reveal this type of issue.
White voids in the printThis is caused by scratches or gouges in the coating of the Magnetic Sleeve. Normally one or two scratches wouldn’t pose a problem however the more scratches there are then the more potential voids there will be. This is especially true when the scratches are all in the same general location.
Light and dark banding across pageThis is caused by a bent or warped magnetic roller. This normally happens when a hub (especially a metal one) is pressed into the sleeve at an angle. Metal hubs should be removed and replaced with a special press and with delicate care.
Intermittent printingA Magnetic Sleeve contact transfers charge from the printer to the conductive black coating on the surface of the Magnetic Sleeve. If the contact is bent out of shape, too much electrical grease applied or installed incorrectly it can print either light or blank pages (most often blank).
PCR (Primary Charge Roller)
The PCR is a roller which controls the charge being applied to the Drum Cylinder. Basically it places an initial uniform charge on the drum then towards the end of the cycle erases the residual charge once more applying a uniform charge. This leads into the next print cycle(each revolution of the drum is considered a ‘cycle’). Because of this dual role, there are some severe failures which can come from the PCR. Most of these failures will show up more in winter where the humidity is low rather than in summer when it is high (this is due to Static build up).