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 page
The 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 vertically
Caused 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 spaced
Calculate 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 page
This 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
Thin line down the page
This 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 drum
The 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 revolution
The 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 Failure
The 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 print
A 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 print
This 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 page
This 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 printing
A 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).
Most Common PCR Failures:
Ghosting:
Ghosting is commonly known as repetition of print already applied to the page (duplication). It is more commonly seen replicating dense print however can repeat all density levels depending on the severity of additional charge (the replicated print is produced in lower density almost producing a silhouette replication of the print, hence the descriptive term "Ghosting". A ghosting issue in general is derived from a charge related problem. This can occur when the outer coating of the PCR is faulty (too much cleaning fluid) or too much conductive grease is applied to the PCR Clips/Housing.A cut or hole in the PCR
This results in a repetitive black mark at equal distance to the circumference of the roller. Sometimes these marks can short out across the Drum Cylinder creating excess charge across the drum attracting additional toner when produces a dark ‘band’ horizontally across the page. The markings and ‘bands’ will be repetitive in nature (7+ repetitions down the page).Random dots across the page
These can either be black dots, or white dots in black areas. This is caused by excess lubrication powder sticking to the PCR. These dots will be repetitive in nature depending on the circumference of the PCR (7+ repetitions down the page).Vertical marks on print, generally found on the LHS or RHS of page
If the cartridge is still fresh and markings appear on the print in a blob or smear like fashion, generally this means the PCR has been marked with conductive grease. Commonly it will be located on the LHS or RHS of print near the PCR Clip/Housing (accidental conductive grease application to PCR coating). If continual printing is done, the grease will smear and transfer to the Drum effectively giving a poor print vertically in the smear zone.The Developer Roller
A Developer Roller is a metal shaft covered in Silicon Rubber with a specially designed surface coating. Both the coating and Silicon Rubber help in storing and releasing electrical charge. The Developer Roller is much like a Magnetic Roller, as they both help in the transferal of toner from the toner supply chamber (hopper) to the Drum Unit. The main difference between the two is how they deal in attracting and repelling toner. A Magnetic Roller utilizes Magnetic Charge, where as a Developer Roller utilizes electrical charge to attract and repel. Magnetic based toner will use a magnetic roller, if the toner is charged then a developer roller is used.Most Common Developer Roller Problems
Light Printing
A worn or dirty Developer Roller surface coating is often the cause of a light printout. The Coating wears out over a period of time and can be accelerated by other factors, such as environment (heat), inadequate Doctor Blade pressure or incorrect/dirty surface coating material. This type of failure will show up more on solid black areas and grey scales. Normal text wont easily reveal this type of issue unless in very severe cases. Essentially less toner is attracted to the Developer Roller than normal.Dark or Excessive Print
Dark or excessive print on the page can be due to incorrect cleaning products being applied to the Developer Roller. The surface coating is a fragile balance of components/materials to aid in attracting or repelling specific toners. This balance can be disturbed when cleaning products are applied, which strip or leave additives (residue) on the surface coating. The majority of cleaning materials are too harsh and often end up stripping some of the coating. This allows the Developer Roller to overcharge causing excess toner to be attracted which leads to dark or excessive prints.Repetitive coloured marks equidistant down the Print
Repetitions measured at the same circumference as the Developer Roller (smaller circumference) will indicate the Developer Roller has been marked. This can occur from sudden force damaging the surface coating of the Developer Roller.Repetitive coloured horizontal lines equidistant down the Print
Repetitive lines measured at the same circumference as the Developer Roller (smaller circumference) will indicate the Developer Roller has been marked. This generally occurs from gradual force from the Doctor Blade pressing into the Developer Roller eventually pitting the roller out of shape.The Doctor Blade
The Doctor Blade controls or ‘doctors’ the amount of toner being applied to the Magnetic or Developer Roller by applying constant pressure to this roller. A worn Doctor Blade can cut grooves or pit a Mag or Developer Roller across the surface resulting in horizontal lines equidistant down the print. The horizontal marks will be measured by the circumference of the roller, ‘white’ void lines for a Magnetic Roller or coloured lines for a Developer Roller and usually extends the length of the roller. An incorrectly installed Doctor Blade will cause light prints due to excessive pressure limiting the amount of toner to the Roller, toner starvation. A worn Doctor Blade will cause an anomaly referred to as ‘Tyre Tracking’ or ‘Sand Dunning’ it’s referred to this due to the appearance of marks. This type of effect is created as the blade isn’t rigid or stiff and the amount of pressure being applied to the Roller isn’t constant, allowing it to ‘flap’ if you will.Recovery Blades
Recovery Blades are thin plastic Mylar blades which guide residual toner back onto rollers or into hoppers. A damaged recovery blade will cause random dots all over the page which can be described as ‘flicking toner’. The most common damage to a blade is it gets bent out of shape during assembly. The toner will then accumulate on top of the blade and drop o or ‘flick’ onto the print. Accumulation of toner will steadily increase with more than the cartridge is used, to a point where it looks reminiscent of a leaking cartridge.Magnetic Roller Bushings
Magenta Roller Bushings are a thin piece of plastic which ‘cuffs’ the end of the Mag Roller, these are to provide and keep a specific gap between the Mag Roller and the Drum. The Drum rolls directly on these bushings. Cracked, worn, missing or toner filled bushings will physically damage the drums coating, often tearing this coating.Toner Cartridge Problem Resources
https://www.youtube.com/watch?v=Jn6DpDC8g8U
https://www.inkcartridgesupport.co.uk/toner-cartridge-troubleshooting/