Home Tech Talk Remanufacturing the HP LaserJet Pro M26 Series toner cartridge CF279A

Remanufacturing the HP LaserJet Pro M26 Series toner cartridge CF279A

by Imaging Solution Bureau

By Mike Josiah and the Technical Staff at Uninet

In October 2016, Hewlett Packard released the LaserJet Pro M26 series of printers. This series of laser printers are based on a 19 ppm, 600dpi engine with a stated first page out in 9.0 seconds. The CF279A toner cartridge is rated for 1,000 pages.

The printer itself has a very small foot print. It’s a nice small office/home machine. The memory is fixed and not expandable at 128Mb. The “W” versions in this series have wireless capability and also mobile print for Android, Google and HP ePrint.

The printer when new comes with a starter cartridge that is rated for 500 pages at 5% coverage, so your customers will be coming to you fairly quickly! (Plus the STD yield cartridge is only 1000 pages)

The printers so far based so this engine are: *

LaserJet Pro M12

LaserJet Pro M12w

LaserJet Pro M26

LaserJet Pro M26nw

List Price for the CF279A is: $54.99*

*As of 12/15/16

Since it’s been a long time since we have covered basic printer theory, I have included it here. You don’t have to know the theory to remanufacture cartridges but it sure helps if you have a problem. Troubleshooting time can be dramatically reduced.

Cartridge Theory:

Figure A gives a nice block diagram of the printing process

The image formation process consists of a series of steps.

In the first step, the Primary Charge roller (PCR) places a uniform negative DC Bias voltage on the OPC drum surface. The amount of the negative DC Bias placed on the drum is controlled by the printer’s intensity setting. This process is part of the latent Image formation block. See Figure B

In the second step, the laser beam is fired onto a rotating mirror (called the scanner).  As the mirror rotates, the beam reflects into a set of focusing lens.  The beam then strikes the OPC’s surface, which neutralizes the negative charge on the drum and leaves a latent electrostatic image on the drum. See Figures C & D

The third step (developing block) is where the toner image is developed on the drum by the developing section, (or supply chamber), which contains the toner particles. The toner is held to the magnetic roller sleeve by the stationary magnet inside the sleeve, and a DC bias voltage supplied by the high voltage power supply. This DC bias voltage is controlled by the printer’s density setting, and causes either more or less toner to be attracted to the drum. This in turn will either increase or decrease the print density. Both the Primary Charge roller and magnetic roller DC Bias voltages are controlled by the printer’s density setting. The amount of toner on the magnetic roller sleeve is also controlled by the rubber Doctor blade, which uses pressure to keep the amount of toner on the magnetic roller sleeve constant. This blade also causes a static charge to build up on the toner, which helps keep the coating of toner even, and allows easy transfer to the OPC drum.

At the same time an AC signal is also placed on the magnetic roller sleeve. This signal decreases the attraction of the toner to the Magnetic Roller sleeve, and increases the repelling action of toner against the areas of the drum that was not exposed to the laser beam. This AC potential improves the density, and contrast of the toner on the printed page. See Figure E

As the laser exposed areas of the OPC drum approach the magnetic roller, the toner particles are attracted to the drums surface due to the opposite voltage potentials of the toner, and laser exposed surface of the OPC drum.

In the fourth step (transfer block) the toner image is then transferred to the paper as it passes below the drum by the transfer charge roller, which places a positive charge on the back of the paper. This positive charge causes the negatively charged toner on the drum’s surface to be attracted to the page. The small diameter of the drum, combined with the stiffness of the paper causes the paper to peel away from the drum. See Figure F

In the fifth step (also part of the transfer block) the paper separates from the drum.  The static charge eliminator weakens the attractive forces between the negatively charged drum surface, and the positively charged paper. This prevents toner dropouts onto the paper at low temperatures and humidity and also prevents paper from wrapping around the drum.

In the Sixth step the image is then fused on to the paper by the fuser assembly, which is comprised of the upper fixing film assembly and the lower fuser roller. The paper passes between a heated upper fixing film assembly and a soft lower rubber roller. The upper heated element then melts the toner into the paper. The fixing film assembly consists of a Teflon sleeve with a ceramic heating element inside. These fusers are a bit different in that they have a Brush which has a DC Bias charge on it to help keep the film clean. See Figure G

In the Seventh step the OPC drum is cleaned. On average, approximately 95% of the toner is transferred to the paper during the print cycle. As the drum rotates during printing, the remaining 5% of the toner that is on the OPC drum is cleaned off the drum by the wiper blade. It is then guided into the waste chamber by the recovery blade, and stored in the waste chamber. See Figure H

Step 8 is where the residual charge is eliminated. Both the PCR and the laser unit are used for this. The Primary Charge Roller places an AC voltage across the drum surface and the laser unit’s second beam erases and residual charges left on the drum. This drum charge elimination is only turned on during the last rotation period of the drum.

Supplies required

Toner for use in the HP LJ Pro M26 series

New Drum

Replacement chip (Dedicated)

Wiper Blade

Dr. Blade

Magnetic roller

Sealing Strip

Cotton Swabs

Isopropyl Alcohol

Drum Padding Powder

Conductive Grease

Tools Required

Phillips head screw driver.

Small Common screw driver

Needle nose pliers

Jewelers Screwdriver set

1) With the handle facing you, Remove the Right side screw and end cap from the cartridge. Be careful of the drum cover spring! Remove it with the end cap.

2) With the pair of needle nose pliers, release both the hopper tension springs.

3) Slide the waste/drum
section over to the left side. Separate the two halves.

4) On the waste/drum section, lift the drum up from the gear side. Twist and remove from the hopper.

5) Remove the PCR and clean with your standard PCR cleaner.

6) Remove the two screws and the wiper blade.

7) Clean out all the waste toner from the hopper. Be careful not to damage the recovery blade located next to the wiper blade. If this blade is bent in any way, the cartridge will leak. Make sure the wiper blade foam seals are clean.

8) Coat the new/cleaned wiper blade with your preferred lubricant. Install the wiper blade and 2 screws.

9) Install the cleaned PCR. Place a small amount of conductive grease on to the black holder side of the shaft. Just a small amount of grease is more than sufficient.

10) Place another small amount of conductive grease on to the metal drum axle.

11) Install the new/cleaned drum hub side first.

12) Place the waste/drum section aside.

13) On the toner supply chamber right side, Remove the two screws and end cap.

14) Remove the gears from the hopper as shown; Leave the large auger gear in place.

15) Remove the single screw and end from the opposite side.

16) Remove the magnetic roller assembly. Be careful of the bushings! They are very fragile.

17) Remove the doctor blade and two screws.

18) Clean out all the remaining toner from the hopper. Make sure the magnetic roller seals and the doctor blade seals are all clean.

19) Fill the hopper with toner for use in the HP M26 cartridge.

20) When a seal becomes available,
remove the seal port plug, and install the seal. Bring the tail out through the seal port hole. Install the plug.

21) Install the left side end cap and screw. Make sure the small contact piece is installed correctly on the end cap.

22) Install the doctor blade and two screws.

23) Install the magnetic roller black bushing side first. Turn the roller until the keyed end locks in place.

24) Install the gears as shown.

25) Install the end cap and screws.

26) Place the drum/waste hopper into the toner hopper. Slide it over so the round hinge pins fit into their respective holes.

27) Set the hopper tension springs back in place.

28) With the drum cover spring as shown on the end cap, install the end cap. Lift up the tail of the spring to fit onto the hopper.

29) Lift up the drum cover sprint tail to fit as shown on the drum cover. Install the screw into the cover.

30) Replace the chip.

Repetitive Defect chart

OPC Drum:               75mm

Upper Fuser Film:       57mm

Lower Pressure roller:  56mm

Transfer roller:        39mm

Magnetic roller:        34mm

PCR:                    27mm

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