HP LaserJet 4
Encyclopedia
Laser printer
A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. As with digital photocopiers and multifunction printers , laser printers employ a xerographic printing process, but differ from analog photocopiers in that the image is produced...
s produced in the early to mid-1990s as part of the LaserJet
LaserJet
LaserJet as a brand name identifies the line of dry electrophotographic laser printers marketed by the American computer-company Hewlett-Packard . The HP LaserJet was the world's first desktop laser printer.-Technology:...
series by Hewlett Packard (HP). The 4 series has various models, including the standard LaserJet 4 for business use, the 4L for personal use and the 4P for small businesses. Additional models included the 4Si model, created as a heavy-duty business printer, and the 4V model, a B-size printer for desktop publishing
Desktop publishing
Desktop publishing is the creation of documents using page layout software on a personal computer.The term has been used for publishing at all levels, from small-circulation documents such as local newsletters to books, magazines and newspapers...
and graphic artists. There are also Apple Macintosh specific variants of these machines with the '4M' designation. Hewlett Packard also released an upgraded version of the LaserJet 4/4M known as the 4 Plus ('4+')/4M Plus ('4M+').
The LaserJet 4, especially the 4/4M/4+/4M+ models, have become known for their durability, mainly due to their reliable construction, as well as the printers built-in PCL
Printer Command Language
Printer Command Language, more commonly referred to as PCL, is a page description language developed by Hewlett-Packard as a printer protocol and has become a de facto industry standard. Originally developed for early inkjet printers in 1984, PCL has been released in varying levels for thermal,...
(and optional PostScript
PostScript
PostScript is a dynamically typed concatenative programming language created by John Warnock and Charles Geschke in 1982. It is best known for its use as a page description language in the electronic and desktop publishing areas. Adobe PostScript 3 is also the worldwide printing and imaging...
) printer language support which is still used in computers to this day. Hewlett Packard dominated the laser printing sector during this time in part due to their reliability, relatively affordable pricing, and the spread of LaserJet 4 models from personal use up to heavy business use.
The LaserJet 4 series was discontinued in the 1990s, and Hewlett Packard recommended the HP LaserJet 4250 as a replacement for the 4/4M/4+/4M+ models. However the driver for the HP LaserJet 4 is often used for other compatible printers as it can solve some tricky software problems with printing. The driver is very standard and can be used with old software with success, even when applied to other makes and models of printers.
Straight Paper Feed
A feature of the 4, 4+, and 4si particularly dear to graphic designers was the straight paper feed. Unusually thick paper could be run through the printers without jamming by setting the output tray to "Lower (face up)" and having it come out the back of the printer. Similar models of earlier HP laser printers had this feature, but it became less common with the later models.Common problems
The EX (and EX+) print engine is known for its reliability and longevity, and in comparison to earlier generations of laser printers, these machines have acquired a 'workhorse' reputation. The engine has a high monthly duty cycle (20,000 pages) and it is not uncommon to find units still functioning well after a million or more page impressions. However, any printer mechanism is subject to wear and degeneration, and typically printers still in use have now seen long service (the machine being discontinued with the introduction of the Laserjet 5 in 1995).Exit path jams
Printers that exhibit the "accordion" or "washboard" paper jam problem with the paper tightly concertina'd or folded in the exit paper path (often behind the rear access door) generally have problems with the paper exit mechanism. In many cases, the delivery rollers (upper and lower) in the upper or final stage of the paper exit are worn or unserviceable. Replacement kits for these rollers are easily obtainable and can solve the problem.An alternative is to enlarge the roller slightly by using heat shrink over the output rollers. The heat shrink extra diameter pulls the paper quicker and resolves the wear/slip issues.
4/4M
Introduced in 1992, this is the original LaserJet 4 with the Canon EX laser print engine. It prints eight pages per minute, and the user cannot extend the feeders.4+/4M+
The LaserJet 4 Plus (4+), released in 1994, was the LaserJet 4 with the improved Canon EX+ engine which increased printing speed to 12 PPM. This also provided the option for duplex printingDuplex printing
Duplex printing is a feature of computer printers and multifunction printers that allows the automatic printing of a sheet of paper on both sides...
(automatic double-sided printing) with the purchase of an accessory (HP part number C3157A). The original 20 MHz processor was also upgraded to 25 MHz, with the addition of Hewlett Packard's Memory Enhancement Technology. The printing mechanism was also improved to allow increased tones of grayscale.
These models also feature a 20-30W power saving (stand-by) mode, which was not included in the original Laserjet 4.
4Si
The 4Si (and 4Si MX for the Macintosh) were heavy-duty business printers, produced using the Canon NX engine. The 4Si worked at 17 PPM, could print on paper up to 8.5"x14", and could be upgraded with a duplexing unit and an envelope feeder.Besides the usual malfunctions common to laser printers with worn rollers or accumulated paper dust, older IIIsi and 4si printers eventually exhibit a "phantom paper jam." On longer documents, the printer will stop and report a paper jam, but with no visible reason why the paper wasn't feeding correctly. There are a couple of solenoids at the paper tray input mechanism that have felt pads designed to cushion them when they snap on, and the glue holding these pads in place can migrate to the surface. This delays the release of the solenoid, which causes the paper to start feeding slightly late. The error accumulates with each page printed, and eventually the paper is entering the mechanism so late that the printer believes that a jam has occurred. The tell-tale symptom is a print job with a top margin that shrinks from page to page. This problem is fixed by removing the felt pads, cleaning off the adhesive (isopropyl alcohol
Isopropyl alcohol
Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...
works well), and placing some electrical tape or other material to provide a cushion for the solenoid. Unfortunately, accessing the solenoids requires disassembling most of the input mechanism.
4L and 4P
4V
The 4V and 4MV were B-size printers for graphic artists using the Canon BX-II engine. Hewlett Packard did not consider the original BX engine as "good enough" for their LaserJet series. The 4V/4MV were released in 1994 and dominated the market due to their competitive price. The 4V series was the first HP printer to offer an internal hard diskHard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
option.
Common Fixes of the LaserJet 4V and 4MV model can have accordion jam as well, caused either by a worn roller or broken tooth on the gear at the fuser door, this can be repaired by replacement of the front fuser door, the engine over all is reliable, problems such as paper jams can be fixed by replacement of pickup rollers located under the toner cartridge, replacement of the fuser door, checking if the paper separation paws are not bent and replacement of the delivery rollers.
4LC and 4LJ Pro
The 4LC and 4LJ Pro were printers based on the 4L platform modified for the Chinese and Japanese markets respectively. The 4LC was the "first printer designed exclusively for the Chinese market", and was released by HP in April 1995. This was followed by the Japanese 4LJ Pro in May 1995. Both of these printers used a 2 byte PCL that had been recently developed for Asian fonts, and came with memory upgrades and Chinese/Japanese fonts. Both printers worked at 600 DPI, with 2MB RAM.Macintosh variants
In all the models of the four series an 'M' designation identifies a version designed to work well with the Apple Macintosh, with additional accessories for network connectivity (JetDirect (Ethernet)Jetdirect
JetDirect is the name of a technology sold by Hewlett-Packard that allows computer printers to be directly attached to a Local Area Network. The "JetDirect" designation covers a range of models from the external 1 and 3 port parallel print servers known as the 300x and 500x, to the internal EIO...
/LocalTalk
LocalTalk
LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer. LocalTalk specifies a system of shielded twisted pair cabling, plugged into self-terminating transceivers, running at a rate of 230.4 kbit/s...
), PostScript Level 2 support and more memory, built-in as standard.
Comparison
| Model | Introduction | Canon print engine | Print resolution (DPI) Dots per inch Dots per inch is a measure of spatial printing or video dot density, in particular the number of individual dots that can be placed in a line within the span of 1 inch . The DPI value tends to correlate with image resolution, but is related only indirectly.- DPI measurement in monitor... |
Print speed (PPM) | Standard memory (RAM in MB) | Maximum memory (RAM in MB) |
|---|---|---|---|---|---|---|
| 4 (4M) | October 1992 | EX | 600 | 8 | 2 (6) | 34 (26) |
| 4Si (4Si MX) | April 1993 | NX | 600 | 17 | 2 | 34 |
| 4L (4ML) | May 1993 | PX | 300 | 4 | 1 (2) | 2 (2) |
| 4P (4MP) | October 1993 | PX-II | 600 | 4 | 2 (6) | 26 (22) |
| 4+ (4M+) | May 1994 | EX+ | 600 | 12 | 2 (6) | 66 (50) |
| 4V (4MV) | September 1994 | BX-II | 600 | 16 | 4 (12) | 68 (52) |
| 4LC/4LJ Pro | April/May 1995 | ? | 600 | ? | 2 | ? |