HP Color LaserJet 2600 Printer Cartridges

The Color LaserJet 2600 Series of printers contains five models:

Color LaserJet 1600, 8ppm, 600dpi, USB, host-based language, A4, Optional tray 3. Limited by having 16MB RAM that is not expandable.

Color LaserJet 2600N 8ppm 600dpi USB and Ethernet host-based Optional tray 3. Limited by having 16MB RAM that is not expandable.

Color LaserJet 2605 12ppm black 10ppm color USB Memory Card Print. Ethernet Duplex and Extra Tray Options. Expandable RAM.

Color LaserJet CM1015 as for the 1600 but with a scanner gives print, scan and copy functions, 96MB RAM gives working memory for complex pages and print languages include PCL 5e, PCL 6, and an HP version of PostScript level3. Color LaserJet CM1017 As for the CM1015 with the addition of memory-card print for photos.

All models take a group of four colour print cartridges:

Q6000A, Black Print Cartridge. 2500 pages at 5% - Q6000A

Q6001A, Cyan Print Cartridge. 2000 pages at 5% - Q6001A

Q6003A, Magenta Print Cartridge. 2000 pages at 5% - Q6003A

Q6002A, Yellow Print Cartridge. 2000 pages at 5% - Q6002A

Cartridges are available as individual items and as packs - for instance HP provide a bundle of two black cartridges to improve the value proposition for black ink:

Q6000AD, Black double pack- 2x2,500 cartridges - Q6000AD

Black print cartridges are rated to provide 2500 pages at 5% cover. The test procedure that should be used to determine how many pages a cartridge prints is described inISO-IEC 19752 .  5% cover is a couple of paragraphs of text - a piece of general correspondence or a typical form on white paper). For HP original branded cartridges the price per unit is just under £50 in July 2012 so superficially the cost per standard page is about 2p.

(Printing white text on black will cost 19 times as much - but that is true for any printer that doesn't have white ink.)

Colour laser printers are often used to print logos and pictures, that quickly builds up the page cover. A full A4 picture not only has 100% page cover, it could be 200% because it will take cyan and yellow to make the green of a field and cyan and magenta to give the blue of a sky and all three colours to give the brown of a ploughed field. A photo of a country scene could work out at £1 per page - that will still be cheaper than a typical inkjet.

Colour cartridges are rated at 2,000 pages. Small-office print runs typically involve more text than colour so putting a bit of extra toner in the black cartridges improves the printer's cost effectiveness. HP later introduced a twin-pack black to improve the price per page still further.

The Color Laserjet 2600 series are suited to printing a typical small-office mix of material including some short runs of highly coloured publicity material. If you were looking for long runs of 50 or more colour brochures this was how that generation of printers stacked up:

Color LaserJet 2600	Black 2,500 pages	Colour 2,000 pages	£48	£51	2.0	2.6
Color LaserJet 3600	Black 6,000 pages	Colour 4,000 pages	£85	£81	1.5	2.1
Color LaserJet 4600	Black 9,000 pages	Colour 8,000 pages	£110	£149	1.3	1.9
Color LaserJet 5500	Black 13,000 pages	Color 12,000 pages	£155	£219	1.2	1.9
Color LaserJet 9500	Black+Color 25k toner 40k drum		195+94	285+183	0.9	1.5

The Color LaserJet 9500 is not directly comparable because it uses separate 25,000 page toners but 40,000 page drums. The black and colour mechanisms are physically almost identical but priced differently so the black copy price is under 1p.

• black price drum-0.5p + toner-0.38p =0.9 p per page
• colour price drum - 0.71p + toner 0.74p = 1.45 p per page

Separating the toner from the drum is common where the aim is a low copy price, the reason HP don't normally do this is that it makes changing consumables a bit more difficult for the user.

Both 5500 and 8500 are also capable of A3.

Cartridges are not the whole cost of running a printer like this.

The colour image is built onto pages held on an Electrostatic Transfer Belt or ETB. The ETB carries the paper over four transfer rollers each with a different transfer voltage pattern. The transfer roller voltages pull the toner across from the cartridge photo-conductors onto the paper in the succession Magenta, Cyan, Yellow and Black

ETB Fuser and pickup roller are likely to last in excess of 50,000 pages - about 20 cartridges. HP's attitude at the time of manufacture seems to have been ambiguous:

• Low cost printers like this might be treated as disposable. If the printer cost between £400 (introductory street price) and £200 (typical end-of-life street price) then then if the whole mechanism were treated as disposable that would add less than 0.5p to the price per page.
• The ETB and Fuser were not made into easily changed plug-in modules. Changing either needs the covers removing and changing of internal connectors - its not difficult but its electrical work suited to a technician.
• Both ETB and fuser are available, although HP did not price them very attractively. The fuser is sometimes available as a refurbished device. ETBs are rarely refurbished. Changing the ETB, fuser and rollers when necessary should halve the non-cartridge running cost - replacing just the part that failed and not the whole printer.

Cartridge Operation

Cartridges are arranged in a stack inside the body of the printer. The transfer belt is in the door of the printer. In use, the belt closes against the cartridges and as it does levers open the cartridge doors exposing the organic photoconductor or OPC.

When a page is printed, the pickup roller kicks a page into the registration station, it then attaches to the belt. The belt carries a page across the cartridges, one after another. As the paper moves up the stack of cartrides it passes over the OPCs.

Cartridges are made in two halves. The lower part contains toner and developer, and the upper part the OPC drum, precharge roller and and waste toner scraper.

The OPC drum rotates past the precharge roller first. The Precharge roller is in the top of the cartridge just behind the OPC drum and pressed up against it by springs at either side. It is electrically connected to the printer electronics through the metal hinge-pin in the blue handle on the right of the cartridge (left side as you are inserting it). The drum gets an initial uniform surface charge from this. Print problems in a refurbished cartridge can come from a poor electrical contact to the hinge-pin because it has been damaged - or because the metal contacts inside the cartridge have been damaged.

The Precharge roller is in a conductive plastic bearing at one side and this should be lubricated with a drop of conductive grease. Resistance from the roller metal shaft to the metal pin should probably be below 300 Ohms. With an ordinary multimeter the resistance of the roller material was unmeasureable above 20 megaohms.

Having gained a charge the OPC drum rotates past a slot between the upper and lower halves of the cartridge body. The laser beam scans it's raster pattern across the width of the slot. The drum's green plastic surface has three layers: the upper one is the charge carrier, and the lowest is the aluminium body of the drum itself. The middle layer is photoelectrically active, when hit with light it conducts so the charge from the top layer leaks away into the aluminium drum. The drum has an electrical contact inside the drive shaft on the left side (right as you insert it). As a result of its pre-charge and selectiver laser exposure the drum now carries a latent image in static electricity.

The latent image carries on over the developer roller. Developer carries a thin layer of toner with it's own charge, partly created by the rubbing action of the feed mechanism (a triboelectric charge) and partly by a high voltage applied to the developer roller itself through contacts on the right of the printer - in this case it is the square metal contact exposed towards the bottom rear of the cartridge on the left as you are inserting it. Where charges differ the toner adheres to the OPC drum as a physical image. If you stop the printer in mid action a little bit of this image will be visible when the drum shutters are opened, just before it gets to the page. (But we don't recommend doing this when there is no need, as that will create a need for extra cleaning).

The developer roller is aluminium with a black coating. One source says the coating is teflon but measurement seems to suggest it is conductive, although that might be exposed metal showing through.

The developer roller is supplied with toner by a stirrer which continually pushes toner in the supply compartment up and forward and by the toner feed roller which is a foam rubber roller loaded with toner in close contact to the developer. The layer is then controlled by a doctor blade set a few microns wide to allow only a fine layer of toner to move out and toward the drum. A developer sheet gives that layer it's final charge.

A page to be printed should be adhered by static to the Electrostatic Transfer Belt (ETB) and travelling past the OPC drum. Behind the ETB belt itself are transfer rollers which attract the toner from the drum surface onto the paper. The transfer rollers connect to the high voltage electronics through tin-plate connectors on down the right side of the ETB - left as you look at it with the door open) and mating springs on the printer body.

A few percent of the toner will not transfer onto the paper and remains on the drum. This toner is presumably not quite carrying the right charge. It is removed by the scraper blade at the top of the drum and is held in the waste compartment at the top of the cartridge. In the CLJ 2600 series cartridge waste handling is nothing more elaborate than the blade and compartment, ther is no mecahnism forcing toner to the back, no illumination of the blade to entirely discharge the drum - just a small compartment.

The voltage on each of the electrical contacts, and on the transfer rollers behind the belt vary as the image is built up. It is quite a complicated pattern. It is possible to measure the voltages using a high voltage probe but obviously this needs some caution. The maximum is something in excess of 7,000 volts. Whilst the power supply circuits delivering this are small and basically designed to provide almost-static electricity they could prove fatal to people. They would also damage any meter not equipped with a high voltage probe.

At the top of the printer the page separates from the ETB as it turns quite sharply and goes under the calibration assembly. The paper exits through the fuser where heat and pressure make the toner adhere.

As well as not all of the toner transfering to the page some of it innevitably tranfers where it should not, to the exposed edges of the transfer belt, and even to electrical contacts. There is no question that this semi-random movement and the amount of waste toner is made worse when the toner powder is not a good match for the machine or if the fine engineering tollerances expected are not well mached by cartridges - both things that can happen with recycled, refilled, and re-manufactured cartridges.

The printer also prints directly onto the ETB at times, notably when told to calibrate. Rather than taking paper from the tray and printing normally during calibration the printer makes patterns on the ETB and then rotates it to the density and registration sensor

To clean toner off the transfer belt the printer uses the cartridges. Voltages are changed so that toner is attracted off the belt and onto the OPC surface and then into the cartridge waste chamber. The magenta cartridge, being the first the belt passes after the desity and registration unit, is likely to get most waste. Waste in the magenta chamber looks a little darker than pure magenta, presumably because there is a mixture of toner grains in there.

Manipulating voltages in this way is obviously quite complicated and it is no surprise to find the high voltage power supply board that does the job takes up most of the right hand side of the printer.

If the voltages aren't correct then either the page image will suffer or there will be toner in the wrong places, an excess of it on the ETB or more than usual on the cartridge contact springs. Look inside the drum shutters - if there is a great deal of toner inside a drum shutter then that cartridge is struggling. Turn the printer off, clean the mess up, then run a couple of cleaning pages and a calibration.

The printer's other noted fault - misalignment - also seems to be associated with use of refurbished cartridges.

Options and Accessories:

HP 250-sheet Paper Tray for the CLJ 1600, 2600N, CM1015MFP and CM1017MFP ( not applicable for 2605dtn which has the tray in the pack) - Q6459A

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