Home Tech Talk Remanufacturing the HP Color LaserJet CM 4540 Series Black and Color Toner

Remanufacturing the HP Color LaserJet CM 4540 Series Black and Color Toner

by Imaging Solution Bureau

The CM 4540 series of multi function color laser printers are based on a 42 ppm black and color 600 x 600 Dpi engine, 3600 DPI with RET. The 4540 cartridges are an all in one type cartridge that consists of the toner supply,drum, and waste chamber. Like a few of the other newer high volume HP Color laser printers, the cartridges in this series are orientated so that the drum faces up not down when placed in the printer. Because of this machine layout, we will take a moment and run through the printer theory before we get started.

 These cartridges are basically a modified HP CP4525 cartridge. In fact the CE260A works in both series as does the waste collection bottle. They all have a toner seal and a snapon drum cover across the bottom to protect the drum. These printers have a separate waste bottle to collect the waste toner from the ITB belt and use chips that’s need to be replaced each cycle. The color cartridges and the HY Black have a larger shoulder on the toner hopper. The major difference from the 4525 cartridges to the HY cartridges in this series are the plastic housing (shoulder) and the drum. The contact hub of the new 4540 drum is larger with the inner hub that houses the drum axle pin stronger and more recessed. See Figures A and B. The old 4525 drum hub design had a tendency to allow the drum axle pin to move out of the hub slightly when
large runs were printing causing print defects. This new design seems to be keeping the drum axle pin firmly in place.

HP Color LaserJet Enterprise CM4540 MFP
HP Color LaserJet Enterprise CM4540f MFP
HP Color LaserJet Enterprise CM4540fskm MFP
The cartridges used in these machines are the:
CE260A (Black)         8,500 pages         $159.99 List*
CE264X (Black HY)   17,000pages         $280.90 List*
CF031A (Cyan)          12,500 pages       $350.86 List*
CF033A (Magenta)    12,500 pages       $350.86 List*
CF032A (Yellow)        12,500 pages        $350.86 List*
CE265A (Toner collection                       $18.00 List*
* Pricing current as of September 2012.

HP -CP 4520 Color Printing Theory
The Color toner cartridge printing process happens in s series of stages or steps. For the purpose of this article, we will call them stages. shows the basic layout of the
cartridges and how they relate to one-another and the printer.Note that the laser units are on the bottom, the cartridges are at an angle, and the ITB is on top.shows the complete image formation process In the first stage, light from the pre-exposure LED strikes the drum to remove any residual charges from the drums surface.tech talk. Then the Primary Charge Roller (PCR) places a uniform negative DC voltage on the OPC drum surface. The amount of the negative DC voltage placed on the drum is  controlled by  the printer’s intensity setting.

In the second stage, a dual laser beam is fired onto a rotating mirror (called the scanner). As the mirror rotates, the beams are reflected into a set of focusing lenses. The beams then strike the drums surface, reducing the negative charge and leaving a latent electrostatic image on the drum. The areas where the lasers did not strike the drum will retain the higher negative charge. These machines have 2 separate laser/scanner units, one for Black and Cyan and one for Magenta and Yellow. Dual lasers are used to allow faster print speeds.

The third or developing stage is where the toner is developed on the drum by the developing section (or supply chamber), which contains the toner particles. The development stage is actually made up of two steps: toner charging, and the actual development. In the toner charging stage, the toner stirring blade turns inside the  hopper. As it turns, friction causes a negative potential to develop on the toner. In addition, a foam feed roller brings the toner to the developer roller and also places a  egative charge on the toner. These two charges help ensure a uniform charge on the toner. Once the toner is properly charged, the toner will coat the developer roller. The toner is also held onto and attracted to the developer roller by another negative DC bias voltage. This voltage is controlled by the printer’s intensity setting and causes either more or less toner to be attracted by the developer roller. This in turn will either increase or decrease the print density. The amount of toner on the  developer roller is controlled by the doctor blade, which uses pressure to keep the amount of toner on the roller constant. As the laser exposed areas of the OPC Drum approach thedeveloper roller, the toner particles are attracted to the drum’s  surface due to the opposite voltage potentials of the toner, and laser exposed areas of the OPC drum.

The fourth stage is the transfer stage. This is where there are some large differences from monochrome printers and also from other color lasers. In the Primary transfer stage the transfer roller which is located directly opposite each OPC drum, places a positive DC bias charge on the back of the ITB or Image Transfer Belt. Each toner cartridge has a separate transfer charge roller. The image is transferred from the drum directly to the ITB. This process is repeated for each color cartridge in the following order: Yellow, Magenta, Cyan, and Black. At the same time, the paper is moving between the Secondary transfer roller and the ITB. As the ITB passes the Secondary transfer roller, the positive charge is picked up, and draws the negatively charged toner off the Belt and onto the paper. Note that this entire process is upside down from
most previous Hp engines. The ITB and  transfer rollers are on top of the OPC drum, not underneath it.  
   The paper separates from the ITB belt as the belt turns back down to start the process again. The static charge on the back of the paper is decreased with static charge eliminator. This helps stabilize the paper feed, and also prevents toner flares (spots) under low temperature and low humidity conditions. In the fifth stage, the image is
then fused onto the paper by the  fuser assembly. The fuser Assembly is comprised of the upper heating assembly and lower pressure roller. The lower pressure roller presses the page up into the upper heating assembly which then melts the toner into the paper. This heating assembly consists of a flexible sleeve with a ceramic heating
coil inside. This type of fuser affords “instant on” fusing with little to no wait time, and low power consumption.

ITB Cleaning:
The ITB is cleaned by the ITB cleaning blade. The ITB wiper blade scrapes off the residual toner and an auger moves the toner to the toner collection box.

OPC Drum Cleaning:
The drum is cleaned after the image is transferred to the paper by the wiper blade. This part is fairly standard; the wiper blade scrapes the toner off the drum, and the recovery blade guides it into the waste chamber.

These printers can print in full color or in black-only modes. To print in the black only mode, the printer disengages the developer rollers in the cyan, magenta, and yellow cartridges. This process also takes place with the Primary transfer rollers and the ITB belt.
Printer Calibration:
At the start of all this is the cartridge detection process, toner level detection,and then the calibration cycle. The printer will calibrate itself wheneverthe printer is turned on (Within 15minutes), when a new toner cartridge is installed and after 48 hours of run time. Calibration consists of a solid block and halftone of each color being printed
to the ITB. As the printed areas get to the top of the belt, a sensor will detect them, measure the density, and adjust the printer accordingly. . All of the calibration time settings are user controllable.
    Taking test prints, cartridge  troubleshooting as well as minor printer troubleshooting will be covered at the end of this article.
Required Tools
1) Toner approved vacuum.
2) A small screw driver (Common Style)
3) A Phillips head screwdriver
4) Needle Nose Pliers
5) Spring hook

Supplies Required
Toner for use in the HP CP4520
New replacement chip
New Long Life CP4520 Drum
New Wiper Blade
New toner feed roller [Optional]
New PCR [Optional]
New Doctor Blade [Optional]
Drum Cover
Lint free Cloths
Conductive grease

The pins in these cartridges are stepped. In other words the outside is thicker than the inside. To remove the pins, you must carefully shave the plastic away from the pins. The procedure is described below
1) Remove the spring from the label side of the cartridge.
2) With a razor knife, carefully shave the plastic from the heads of the hinge pins on both sides of the cartridge.
3) On the label side only, drill a shallow hole on each side of the pin .
4) Remove the pins with flush cutting wire cutters. The smaller pin fits on the contact side of the cartridge, the long pin on the label or gear side.
5) On the gear side, press in on the plastic locking mechanism.
6) On the opposite side lift up on the black lever. Lift the two halves apart.
7) On the waste chamber, remove the two screws from the drum gear end cap. Press in on the tab as shown and remove the end cap. There is no need to remove the opposite side end cap.
8) Remove the drum.
9) Remove the PCR by lifting up on  the black and white PCR locking arms. Remove the PCR Assembly.
10) To remove the wiper blade, the  amber film assembly needs to be removed. Slide a razor knife under the plastic mounting bar, and remove the assembly.
11) Remove the two screws from the wiper blade. Slide the razor knife along the back edge of the blade to release it from the glue. Remove the Wiper blade.
12) Clean out all the waste toner from the chamber. Try not to get any toner on the WB seal if possible.
13) Clean the felt seals on each end of the wiper blade. If the WB glue has toner on it, clean it off with alcohol and a foam swab. If it does not become sticky again, it needs to be removed and a good silicone caulk used to seal the blade off. GE 100% Silicone and Phenoseal are two good brands for this.
14) Install the new wiper blade and 2 screws. If you removed the WB glue, seal the back edge of the blade with the silicone now.
15) The amber film assembly is held in place with double sided tape. If this is not sticking or a new wiper blade is being used, replace the tape. Replace the film assembly.
16) Clean the PCR with your preferred cleaner and install in the cartridge with the PCR holders. Make sure you lock the locking arms in place.
17) Install the drum. Short hub side onto the long drum  ground pin.  
18) Install the end cap and two screws.
19) Place the waste chamber aside.
20) On the supply chamber, remove the screw from the gear side end cap.
21) Press in on the tab and remove the end cap.
22) On the center gear, press on the locking tab to release the gear. Remove all the gears as shown except for the mixing blade gear and the sealing strip gear. The mixing blade gear is attached to the mixing blade inside the hopper and is very difficult to re-attach properly.
23) On the contact side, remove the 2 screws, press in on the  tab and remove the end cap.
24) Remove the three developer roller drive gears.
25) On the gear side inner end cap, remove the two screws and end cap.
26) Remove the developer roller.
27) Remove single screw and contact side inner end cap.
28) Remove the two screws from the doctor blade and start to lift the blade up. There is glue on either rend of the blade. As you lift the blade up, slice the glue away from
the blade with the razor knife.
29) On the right side of the chamber lift up the felt developer roller seal. Lift it from the front side and lay it over the back.
30) Remove the white felt washers from both sides of the feed roller.
31) Pry out the rubber feed roller bushing from the right side.
32) Remove the feed roller.
33) Clean out the remaining toner and fill with the correct color of dedicated CP4520 toner.
34) When a seal is available, install the seal onto the seal rails. Pull the release tape off 1” at a time and press the seal in place as you go.
35) Remove the seal port and slide the seal pull tab through the slot. Install the seal port.
36) Install the feed roller and rubber bushing.
37) Install the feed roller felt washers.
38) Press the developer roller felt seal back in place. Make sure it fits under the retaining blade. If needed, clean the adhesive with alcohol and a foam swab.  
39)Use the appropriate shims to gap the blade and install the doctor blade and two screws. Make sure the sticky seals on either rend of the blade seal correctly. If the material is no longer sticky clean it with alcohol or replace it with a small amount of silicon.
40) Clean the contacts and replace the conductive grease on the inner contact end cap. Install the inner contact end cap and screw.
41) Install the cleaned developer roller. (DO not use any chemicals to clean this. A lint free cloth works fine.
42) Install the inner gear end cap and two screws.
43) Install the gears in the order shown. If you installed a seal, slide the seal end through the take up gear and wrap the loose tail tight on the roller.
44) Install the remaining gears in the order shown.
45) Install the outer gear end cap and screw.
46) Place the triple gear on the developer roller shaft and fit into the spring assembly on the end cap. Install the opposite side end cap and install the screw.
47) Place the two halves together contact side first. On the  gear side, press the lever in place. On the contact side snap the lock up into the end cap.
48) Install the two pins. Large pin to the label or gear side of  the cartridge.
49) Install the spring.
50) Remove the chip by cutting the plastic off the edges of
both side of the chip.
51) Remove and replace the chip.
52) If the new replacement chip is loose in the slot. Close off  the top edges with small amounts of hot glue.
53) Install the drum cover on to the cartridge.

Taking Test Prints


Scroll to and touch the Administration button
Open the following Menus:

Configuration/Status pages
Configuration Page

Touch the Print button

Print Quality TEST PAGES

Scroll to and touch the Administration button
Scroll to and touch the Troubleshooting button
Touch the Print Quality Pages button
Touch the PQ Troubleshooting Pages button
Touch the Print button

Follow the instructions on the pages that print out.

Diagnostics Page

Scroll to and touch the Administration button
Scroll to and touch the Troubleshooting button
Touch the Print Quality Pages button
Touch the Diagnostics Page button
Touch the Print button

Follow the instructions on the pages that print out.

From the Home screen, touch the device Maintenance Button
Open the following menu’s:
Cleaning page
Touch the Print button
The cleaning process will take several minutes

Repetitive Defect Chart:

NOTE: The HP service manual is less than helpful on repetitive defects with their current chart. The first description is HP’s. I have added in what we know for the second. This second description is based on the older HP CP-4025 service manual and our tests.

Distance         HP Description       Our description

27.0mm           Print Cartridge          Primary Charge Roller
32.0mm           Print Cartridge         Developer Roller Sleeve
44.0mm           Transfer unit             Secondary Transfer Unit
48.0mm           Print Cartridge
51.0mm           Transfer Roller           Primary Transfer Roller
55.0mm           Print Engine
63.0mm           Transfer unit            Secondary transfer backing roller
76.0mm           Print Cartridge          OPC Drum
76.0mm           Fuser                        Fuser Sleeve
80.0mm           Fuser                       Fuser Pressure Roller
96.0mm           Print Engine
101.0mm         Print Engine

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