Specifications

Caution
It is particularly important to follow the manufacturer’s recommendations regarding safety whenever you are working inside
a laser printer. Apart from the obvious danger caused by live electrical connections, be aware that some components are
very delicate and can be damaged either by rough handling (such as the developer unit and the corotrons or corona
wires) or by excessive exposure to light (such as the photoreceptor). In addition, the printer’s fusing mechanism is designed
to heat up to 400° F or more and might remain very hot for some time after you unplug the unit. Always allow the printer
to cool down for at least 15 minutes before performing any internal maintenance that brings you near the fusing rollers.
Most inkjet cartridges contain new nozzles and a new ink supply, which prevents problems caused by
nozzles that have become clogged with dried ink. Similar to lasers, thermal inkjet printers also rely on
a powerful heat source, so you should take precautions before touching the internal components.
Low-cost inkjet cleaning kits can be purchased to help keep your inkjet printer free of ink build-up.
Some work with a specially textured cleaning sheet you spray with the cleaning fluid provided with
the kit and then run through the printer by printing a few words. These work with all brands and are
particularly useful with piezo-electric inkjet printers, such as those made by Epson, because these
printers do not allow the user to remove the print head. Others let you clean the print head after you
remove it from the printer; these work with Canon and HP models.
To avoid inkjet problems, be sure you turn off the printer with its own power switch, not the surge
protector or power director! The printer’s own power switch initiates a controlled shutdown of the
printer, including capping the print heads to keep them from drying out. If you turn off the power
externally (with a surge protector, for example), the print heads might dry out because they’re
exposed to the air, which eventually clogs them beyond user adjustment.
Minor clogging of inkjet cartridges can sometimes be cured by using the printer’s diagnostics routines,
accessible either through push buttons on the printer or through the printer’s property sheets in
Windows.
Dot-Matrix Printers
Dot-matrix printers are more prone to collecting dirt and dust than are any other type of printer. This
is due both to the physical contact between the inked ribbon and the print head and to the use of
continuous feed paper. As the printer runs, a fabric ribbon turns within its cartridge to keep a freshly
inked surface in front of the print head. This lateral movement of the ribbon, combined with the con-
tinuous high-speed back-and-forth motion of the pins within the print head, tends to produce an ink-
saturated lint that can clog the print heads and smudge the printed characters. Film ribbons can help
reduce these problems and provide better print quality but at the cost of a shorter ribbon life.
Continuous feed paper presents another problem. This paper has perforated borders on both edges
with holes the printer uses to pull the paper through the printer. Depending on the quality of the
paper you purchase, some of the dots punched out to produce the holes might be left in the pad of
paper. As the paper passes through the printer, these dots can be left behind and eventually can inter-
fere with the paper handling mechanism. Keep dot-matrix printers clean by removing the dots and
dust with canned air or a vacuum cleaner and swabbing the print heads regularly with alcohol.
Choosing the Best Paper
Both laser and inkjet printers use cut-sheet paper exclusively and are therefore prone to paper-han-
dling problems, such as paper jams and clumping (multiple sheets feeding simultaneously). You can
minimize these problems by ensuring that you use paper intended for your printer type. This is espe-
cially true when you are printing on unusual media, such as heavy card stock, adhesive labels, or
transparencies.