HP LaserJet Enterprise M601, M602, M603.

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HP are the worlds largest printer brand and particularly strong in office laser printers.

This web-page summarizes what we know about the LaserJet M601 series. M601, M602, M603.   Information is drawn from several of HP's brochures, the user guide CE988-90901 2011 and service manual CE988-90945 2011.

The M601 series were introduced in 2011 as successors to the P4014 series.

In turn they have been replaced in 2015 by the M604 series (M604, M605, M606).

The M4555 is a multifunction copier based on the same engine, and the M630 is its successor.

The HP LaserJet Enterprise M601, M602 and M603 are key products intended for offices where paperwork is critical.   Users are typically involved in law, finance, medicine and education. The readability, clarity and traceability of paper are highly valued. In that kind of use, printers like this are typically shared in a workgroup of four to six people. The printer might stand on it's own table in small businesses. A fairly typical "corporate" deployment will put the printer on a stand with three or four trays and the output mailbox giving everyone the flexibility to use different kinds and colours of paper - something they could not get with individual printers.

Another thing little printers don't deliver is economical print. The M601 can deliver print at a penny per page and the M602 and M603 can take larger 25,000 page cartridges delivering a page for 0.7p.

Then there is reliability. These printers are descendants of the LaserJet 4000, still in use seventeen years after manufacture. Whether modern build quality will give that degree of longevity remains to be seen but its a possibility thanks to the modular structure of these machines.

Modularity is another feature. When the fuser in a little printer comes to the end of it's life the engineers have to decide whether it is more economical to repair or replace it. With these printers the fuser is a module intended for end-user replacement. Rollers just clip into place. Even the formatter slides out so it can be replaced - a rare need, but possible.

The big cartridges, long life and replaceable parts make this a green option as well.

Other uses for printers like this are to produce things like despatch notes and waybills, things that have to be produced quickly in a warehouse environment. Thermal printers are popular in to produce till-rolls in shops but they are problematic and costly with standard cut-sheet paper. Robust laser printers like the M601 series can tolerate environments inkjets wouldn't.

One thing you can't do with the LaserJet M601 series is print in colour; and that may be part of it's charm as well. Mono laser printers are significantly simpler than colour machines. Where colour machines offer all sort of user lockouts to prevent the staff printing their holiday snaps the mono printer offers the ultimate deterrent - lack of incentive. If you really must have colour look at the M552 or M651.

Value Proposition

The three models in the series are almost identical in terms of hardware and general capabilities. The main differences are print speed and cartridge capacity. The M601N prints at 43 pages per minute, M602 -50ppm and M603 -60ppm. Speed differences are set in firmware. Cartridge type is determined by the plastics of the case and the cartridge chip. In other words you buy into a "value proposition":

  • The M601 is aimed at users with lower print volumes who want the long lasting "industrial" qualities of the machine but don't want to pay over £400 for a printer and don't mind slightly higher running costs.
  • The M602 and M603 are aimed at users who need the highest speeds and have print volumes demanding low running cost.

The M4555 is a 52ppm multifunction copier-printer based on the same print-engine

Form Factor

The printers are more or less cubic with an "S" shaped paper path from a cassette that slides in underneath to a delivery recess on the top. The cassette has 500 sheet capacity and so does the output bin. An alternative input path is from the multipurpose tray (MP) that folds down at the front. An alternative output normally used for heavy media is to the drop-down tray on the back. In most respects the printer is highly conventional. With the LaserJet P4014 HP moved to having four motors driving the paper path and that continues here … lifter, main-motor for pickup, drum-drive and fuser-motor as well as the laser scanner and four fans.

All of these printers have very similar engines which evolved from that in the HP's P4014 series.

M601 Printer Cross Section

This page overviews the printer mechanism using a cross-section diagram. These printers are highly maintainable, parts likely to wear out can be changed with nothing more than latches and clips.

The M601 series is strongly based on the heritage of the LaserJet 4200, 4350, and P4015.   Anyone used to working on those printers will find the principles and some of the parts familiar.

general principles

Cross-section showing the print-paths from the cassette and the duplexer.

General Principles

Paper normally travels in an "S" shaped path outlined in dark blue. Paper normally comes from the tray under the printer where it is picked up and driven towards the registration station by the cluster of three rollers shown in pink.

An alternative route is from the drop-down multipurpose tray on the front of the printer. It is shown folded up, the rollers are shown coloured lilac. In practice rollers are blue, white, grey and black.

Paper is straightened and momentarily held in the registration station then released to pass between the photosensitive drum and transfer roller where it picks up the image. The cartridge holding the drum and toner is shown coloured green here, the whole print cartridge is user-changeable and disposed of or recycled when the toner runs out.

The laser scanner (shown blue) has a semiconductor laser which is rapidly modulated with the data to be scanned onto the page. This points through a mirror into the cartridge and onto the photosensitive drum.

Paper then passes into the fuser (coloured orange). The fuser sleeve unit heats the material that passes under it to the point where toner softens and adheres to the paper, the pressure roller drives the toner into the material. The resulting documents are neat and robust.

Paper can simply exit onto a rear tray but normally heads up into the tray on the printer top.

Duplex models of the printer have an extra mechanism that slides in at the back. (Machines are field-upgradeable with the CF062Aunit) The duplexer takes over the delivery path when needed and reverses the paper as it gets to the intermediate delivery roller and pushes it down the back and under the fuser, along the underside of the printer and back up into the registration station. The page is now the other way up, making double sided print possible.

Consumables:

The main consumeable is the print cartridge. There are two versions:

HP 90A (CE390A) Black toner cartridge with 10,000 page yield for the M601, M602, M603 and the M4555.

HP 90X (CE390X) Black toner cartridge with 24,000 page yield for the M602, M603 and the M4555.

These cartridges cost as much as some printers! On the other hand they last more than 10 times as long as the cartridges for low cost printers.

With HP original cartridges these printers are usually trouble-free. You can, of course, Around three-quarters of the problems likely with a printer can be solved by changing the cartridge.

Paper misfeeds and fuser failures may need the maintenance kit.

Spares:

Paper Jam

Paper jam's sometimes called "misfeeds" are often readily detectable because the printer will stop and a piece of paper has to be removed. Very often the paper is just a bit displaced from the tray, sometimes there doesn't appear to be any paper trapped, the printer just goes to Error 13 which is Paper Jam.

Paper jam problems are usually solved by changing the relevant pickup and feed roller set. It is possible to diagnose problems more precisely, the printer has a set of paper detectors (a few are higlighted in yellow) which are supposed to move after the rollers operate and if they don't software stops the printer and shows Error 13.

Fuser Faults

Fuser problems can often be detected and reported by the printer as a 50.1 error or similar. The fuser sleeve unit contains a powerful heater which helps fix the image created in toner powder onto the page. If the heater fails the printer can detect the problem and report an error.

The toner image would stick to the fuser-sleeve except that it is made from a teflon-like material on a metal foil. After one or two hundred thousand pages the foil's non stick properties degrate and the metal backing may degenerate. The printer can't detect this but the user can - some of the toner won't stick to the page properly and bits of fuser material come out the back of the machine and even into the paper tray. The fuser then needs replacing.

CF065A Maintenance kit for HP M601, M602 and M603. Contains a fuser, transfer roller and a set of pickup and feed rollers. If the fuser in one of these printers has failed or the printer says it is worn out then rollers probably need replacing. The printer is likely to show Error 13.

RM1-8396 Fuser alone. Fusers sometimes fail prematurely due to accidents like labels getting stuck, sharp objects passing through or power surges damaging the heater. The printer will show Error 50.

FKITP4014 Paper Feed Repair Kit. Paper feed rollers sometimes wear more rapidly than expected due to differences in paper weight and quality, or to users adjusting paper feed guides to tightly.

CB506-67905 Paper Feed Repair Kit for Tray 1 - the mulitpurpose drop-down tray often used for envelopes or letterhead.

CB506-67904 Paper Feed Repair Kit for Tray 2 and 3,4,5 or 6 if they are fitted. These cassette drawer(s) slide into the printer base.


Service:


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