Canon LBP6000, HP LaserJet Pro P1102, M1132 and M1212 Fuser RM1-6873.

These printers are all based on the same LBP6000 engine. They are low cost printers and perhaps for that reason the fuser is made in two parts:

• RM1-6873 - Fuser Film Assembly
• RM1-6921 - Paper Delivery Assembly

A fuser fault will probably stop the printer. On the HP M1132 it will give an error with the Power and attention light lit and E7 on the numeric display. The error probably indicates that the fuser thermistor did not come to temperature when the fuser was tested during initialization.

Printers with nothing but a ready light may just stop. The computer's print-driver should give a more explicit error message.

The printer is not be able to detect every fuser error - it's only specific detectors are the thermistor, delivery and paper width sensor. If the fuser film breaks up the only indication may be that toner doesn't adhere to the page properly and bits of burned looking grey plastic appear in the output tray.

This idea of having the film and heater as a separate unit was used in the HP LJ 5L and 6L. It makes some sense in low cost printers as only the bit likely to fail is replaced.

All the printers in the LBP6000 family will need all the covers removing to change the fuser. The need to strip the printer down to change a part like the fuser adds significantly to the repair costs.

The obvious question with low cost printers like this is whether they are worth fixing at all or should they just be treated as disposable. Economics may currently suggest one answer, environment another.

Low Cost Printers and Spares

Larger printers have the fuser made as a module and on machines like the LaserJet P4014 - M601 series it slides into place. Low cost printers are rarely anything like this.

Low cost printers may not be specifically designed to be difficult to service but they are generally more difficult to deal with.

Modularity clearly has a cost. Extra materials to give individual modules structural integrity, connectors so that the part just slides in - and perhaps thought given to the design. It is the same problem as making a print cartridge and manufacturers turned that to their advantage. The fuser could be a module, but at the moment making a printer almost entirely out of modules and getting the cost right down seems to be an elusive goal.

Another problem with all low cost printers is whether work like fuser replacement can be worthwhile at all. The price of parts like the fuser are sometimes very close to the price of a printer. Low cost printer meets high priced spare.

Printers ship in huge volume through supermarkets like Tesco. Laser printers like this tend to go through outfits like Staples and Argos (they are sometimes derisorily known as Argos Specials in the trade). So the printers are shipping in container-loads to box-shipping retailers happy to make £5 on a unit. The manufacturer may actually be make a loss on the printer, but will do this if they get sales of cartridges. It's sometimes called the razor & blades sales model; give the razor away to get sales of proprietary blades.

Spares don't share these characteristics. If printer manufacturers do make spares easily available they will get to sell some more cartridges for the printer - but at the cost they don't get to sell a new printer and then some smaller cartridges. Manufacturers might even see spares as an obstacle to sales.

Logistics for spares are different to those for printers; spares ship in low volumes through specialists. It is quite possible for the cost of a spare to climb close to that of the printer. Tesco can sell a lot of printers - but it's no good piling fusers high and hoping to sell them cheap.

As the price of a spare rises too close to that of the machine it is used to repair then obviously demand for the spare itself never really materialises. That actually drives up its price because a request for spares is unusual and the logistics chain is not setup up to deal with any requests that do happen. Pricing hits a sour spot where spares for low cost printers can be unnecessarily expensive.

What we tend to see is that distributors report the parts as obsolete - they aren't actually obsolete, they just aren't showing up in manufacturer's UK systems because non ever shipped here.

Environment

Throwing out a printer because spares aren't available at an economic price is something of an environmental disaster of course. For lack of a fuser foil weighing 1 gramme 7 kilos of rather sophisticated machinery including a laser scanner, microprocessor sub-system and power supply all head towards the skip.

HP has a 6 page Product Environmental Profile for the HP LaserJet Pro P1100 Printer series outlining the merits of their version of the printer. HP Planet Partners will take back old printers and HP say Products returned to HP will be recycled, recovered or disposed of in a responsible manner.

In the end, however, there isn't much metal content in machines like this and it is mixed with a great variety of plastics. The US EPA estimates that only 15-20% of e-waste is recycled, the rest goes to landfill or recycling. ( "Statistics on the Management of Used and End-of-Life Electronics")

We can't really blame the manufacturers for this. They deserve congratulating for turning the laser printer of the 1970s which was half a million pounds worth of machinery into a little desk-top box where the basic models ship for under £50. It is the customers choice to buy a machine without considering repairability.

Manufacturers can't easily opt-out of competing on low-cost printers because they would sacrifice their own revenue and competitors would simply take the business.

Nevertheless if your organisation has an environment policy you will want to see spares available for repairable IT equipment like these machines.

Testing the Fuser

Before replacing the fuser it may help to confirm that it really is faulty.

Degeneration of the fixing-film is the most likely which is a tube of teflon-type material wrapped around a ceramic heater. The pressure roller rotates as paper arrives at the fuser and this drives the fixing film round. Because the fixing film moves fairly freely the softened toner does no smudge on the page.

A breakdown in the film is usually self evident - bits of it will emerge in the output tray. The fuser isn't particularly visible in some of these machines so it may be necessary to open the printer up to confirm the problem visually

The other common failure is of the fuser heater, which is a metal or carbon trace on a ceramic rod. Wear or a power surge ultimately cause the heater to fail. Heater failure is not visible so to prove it meter the resistance of the fuser power leads - the larger connection. If it is open circuit the heater has probably failed.

There is slight room for doubt as to whether a fuser with an open circuit on the power leads has actually failed because it is worn out; it is just possible the control circuit has failed and damaged the fuser. The Service Manual doesn't make it entirely clear whether the thermal fuse is self-resetting. It is possible for the fuser control circuit to break down and damage the fuser - in which case a new replacement will also be damaged. Such an event may be possible but it would be rare. Other than checking the thermal fuse in the old printer that is difficult to eliminate.

The thermistor might fail but it is replaced by a new fixing-film assembly.

Replacing the Fuser

Replacing the fuser components means first removing all the case parts on these printers.

The last cover to come off is the metal rear cover plate.

Careful observation of where wires are coming from will be a big help in reassembly.

The wiring harnesses leading to the fuser need to be released from securing clips around the printer body. There are three sets of cables: power, thermistor and some for the delivery and paper width sensors. Note the routing as cables need to be tucked back in position when the machine is reassembled.

On an unfamiliar printer it might be helpful to mark the cable routing with little dots of Tippex in places the cable doesn't touch.

The fuser assembly is held by 3 (?) screws.

With the wiring harnesses unhooked the fuser can be split to get access to the fixing film assembly

The fixing film assembly and pressure roller are pressed together by a pressure arm and a spring loaded pressure plate. The arm, plate and spring need to be taken off and set to either side so that they can be replaced in the correct position.

The old fixing film unit comes out and the new one drops into place.

To replace the fuser the disassembly process is reversed. Careful observation of where parts came from will help reassemble things correctly.