Printer Information and Troubleshooting

• Types of Printers
• Printer Languages
• Connections and Protocols
• Types of Stock
• Troubleshooting
  

Type of Printers

Most printers fall into four general categories: Dot Matrix Printers (DMP), Laser Printers, Jet Printers, and Wax or Dye Sublimation. Two other types, the Daisy Wheel and the Plotter, are sometimes encountered.

Dot Matrix Printers

Dot matrix printers use a head with pins (usually 9 or 24) arranged in a vertical column. The pins strike a ribbon which coated with a lubricating ink or a plastic tape as the head passes from side to side. Sometimes the head will lose a pin and will nee d replacement--the symptom of this is a horizontal white bar where that pin fails to strike. Dot matrix printers on the PC generally emulate the PC Graphics printer (with line draw characters in upper ASCII) or the Epson (with italic characters in upper A SCII), with a dip switch controlling the emulation mode.

Laser Printers

Lasers use a personal copier engine and a laser beam to construct the image of the page on a drum with charged toner, which is then laid onto the paper and fused with a heat roller. Laser printers can sometimes emulate daisy wheel or DMPs, but they are usually driven by postscript or HP PCL.

Daisy Wheel

This is the oldest type of printer, using a wheel upon which characters are present in reverse relief, The wheel spins to the correct character, and a hammer forces that character first against a cloth or mylar ribbon, and then against the paper. Daisy Wheels are expensive, limited to one typeface and character set per wheel or head (which means multi-font documents require changing the wheel or head during the print job!), slow, and noisy. The De-facto standard is the Diablo 630, and you will find that a number of other printers (such as lasers) can emulate this model.

Jet Printers

Jet printers are a low cost alternative to lasers. They use a head with a vertical line of holes, from which ink is sprayed by virtue of a heating element. Jet printers provide good quality at a low initial cost (~300.00) but they are not particularly sturdy, and the cost per page is high compared to a laser. Also, the water based ink can be sensitive to the cotton content and relative moistness of the paper used. Luckily, the econo bond sold in student stores yields consistently good results.

Wax and Dye Sublimation

These are usually color printers. Wax or Ink Jet based printers yield reasonable results at a low cost. These printers use a dithered pattern of dots to produce colors, which can lead to interesting color representations (for example, gold usually comes out as yellow with flecks of purple). Dye sublimation yields the highest quality of color, as it uses a mix (usually CYMK) of inks to produce colors, rather than a dithered pattern of dots, and are suggested for high quality graphic work.

Plotters

Plotters are designed for large line drawings, and are used for CAD work and blueprints. Plotters usually use pens holding different colors of ink.

Printer Languages

All printers support a "language" in the sense that they translate received ASCII codes and translate them into an action. A printer driver can therefore be thought of as a translation device, in which general formatting or other printer requests from th e application are translated into the language understood by the printer. If you use the wrong driver, the printer hears babble, and will respond erratically. If the driver is speaking a language close to that of the printer (such as a PC Graphics Driver communicating with an Epson DMP), you will see some of what you want to print, but you will get other stuff as well (such as graphs with italic characters as the axes). In this respect, Postscript is just a more sophisticated language than PC Graphics. Also, most printers can speak more than one language, and can be changed from one mode to another with a dip switch or by sending a code to the printer. Here are the languages you are likely to encounter with various types of printers

Daisy Wheel     Diablo 620/630
DMP        	Epson, PC Graphics, Proprinter, Imagewriter
Laser      	Quickdraw, Postscript (I and II), PCL, Diablo 630
Jet             Quickdraw, Postscript, PCL
Wax, Dye Sub    Postscript, PCL
Plotters        Postscript, custom driver
 

Connections and Protocols

Printers support a variety of connections. Lower cost models generally have either a parallel or serial port. More expensive models usually come with both, and may also support localtalk or ethernet. Some of these latter models can support multiple connections (usually called auto-sensing or auto-switching). Other printers have multiple ports but can use only one, and require configuration with a dip switch or the lcd menu. Information on such features is found in the printer manual.

Networkable printers represent a particular challenge in that one must also consider the communications protocol supported by the printer. For example, a laser printer that supports ethernet can reside on the same network with Macintosh computers, but if the macs are to print to the printer directly, the printer must support the Appletalk communications protocol, since that is what macs speak. Other protocols in common usage are IPX (novell netware) and TCP/IP (unix). Some models of printers are upgradable in this regard, using slots or cartridges to add daughterboards enabling additional functions, but be careful when considering such an upgrade--adding postscript may, for example, require additional memory be installed, or a network connection to ether net might need to be augmented by the Appletalk protocol to be useful to macs.

Novell servers are very flexible in their capability to network printers. Netware servers can support all three common protocols, and can bridge localtalk and ethernet networks. In addition, Netware servers can support serial and parallel connections, and the novell print services can allow connections from the net to these printers. Finally, netware supports a utility called RPRINTER that allows a pc to serve as a remote printer port for a netware server, such that so long as the pc is on (whether or not it is logged into a server) that printer is available to the novell print queues. Likewise, Apple provides a variety of software solutions that help with printer configuration on a network. One recent product is Ethernet/Localtalk Bridge (about $60.00), which allows a mac to bridge local talk cable to ethernet, such that when the mac is on, the localtalk segment appears in the same zone as the macintosh. This allows you to use older Laserwriters and Appletalk Imagewriters with ethernetted macs.

Types of stock.

Paper is the most common stock used in printers. You should consider the type of printer you have when buying paper. Some general guidelines (check the printer manual for details):

• Smoother stock yields better results than rough in laser printers.
• Paper with a high cotton content will often cause ink from jet printers to bleed.
• Ink from jet printers is generally not waterproof, although water proof ink is available.
• If your output is too grey, photocopies of the original may appear darker.
• When using acetate, make sure you have the right kind. Some acetate will melt on the rollers of a laser printer, and others don't take ink well. Sometimes it makes a difference what side you print on as well.
• Don't use fanfold paper in printers not designed for it--the micro perforations for the track strips and age breaks leaves dust behind that can damage the printer.
• Some types of paper are very sensitive to humidity. If you live in a humid environment, you might consider keeping it in a zip lock bag.

Troubleshooting

Often the printer prints, but what comes out isn't right. Here are some typical problems:

• Print is faint. Could be that the printer is low on toner or ink. Laser printers usually have an adjustment dial for toner weight. DMP and Daisy Wheels use ribbons, which like those found in typewriters tend to dry out. You can rejuvenate ribbons using WD40--open the cartridge, spray lightly, re-seal, and let sit over night.

If the printer doesn't print anything at all:

• Did this setup ever work? If not, who set it up? If so, did something happen (software was installed, printer moved,etc.) prior to the failure?
• Do you have some sort of printer queuing enabled? Macs use background printing, Windows have a print manager, and printers accessed through servers have print queues--sometimes the print job is going to a queue and dying there, so bypassing or disabling the queue can be a good test.
• Check the cables. Make sure the connections are in the right port (careful!) and fit snugly.
• Does the printer pass it's diagnostic tests? Check the manual for specifics, but usually you initiate a test by holding down one or two buttons while turning on the printer.
• Does the printer fail for all applications? (Try teachtext, simpletext, notepad, write, etc.)
• Is the printer accessed via a network? Check the cables; if there is a direct connection between the serial or parallel port and the printer, it's not a network problem. If the printer is connected to an ethernet or localtalk cable, or to another pc, or to a server, it's probably a networked printer.
• Macs: Can you see the printer in Chooser? Networked printers should report their name in the dialogue box to the right of the printer icons. Printers connected via serial port will allow you to choose between the modem and printer icons to choose the port used.
• PCs: Try a printscreen. Actually, try three in a row, since a printscreen is 24 lines and a triple pump will clear 66 lines, thereby forcing a form feed in printers that hold the page in a buffer. You can also try copying a file (autoexec.bat is a good choice) to the port to which the printer is attached.
• When you send a print job, watch the printer's LEDs or lcd panel. Most printers will blink the on line indicator as data is feed to the printer and the printer processes data preparing output.
• If the on line light blinks steadily, but there is no output, the printer's software may be hung. Give it time though; older laser printers can take as long as two hours to process complicated print jobs. In such cases it may be useful to print the postscript out to a file, and then try to copy the file to a printer via another route. Most postscript drivers support output to file. From a dos machine you can copy the file to the port to which the printer is attached (eg. copy filename.ext lpt:1). From a Macintosh, you can use Send PS, a shareware program available on most FTP sites.

If you get output:

• Printer prints mostly clear text, but with instersperced odd characters or sudden formatting shifts. Check the driver to make sure the the right one is selected.
• Printer prints, but in gobblegook. Usually a driver problem. Try reaching the printer via another route (print queues can sometimes cause problems) and selecting a different driver. Consider reinstalling the driver.
• Text lines up correctly on the left side on the screen but not on the printed page. Check to see that the user has proper tabs and tab stops. In proportional fonts, spaces cannot be used to align text, since a space is variable in width.
• Font is set correctly, and driver is correct, but font selection on printer is incorrect. 1) Macintosh. If the font is close in terms of appearance, it is most likely that font substitution is on and no high quality version of the font is available. In such cases the Macintosh OS will use a high quality font of the same family. If the font is n on-standard, it may be that it's name, id number, and family data are incorrectly coded, and you are getting interference from another font. Try setting up a virgin system with just the one font that is acting up and turn off font substitution. 2) PC. If the font printing is courier, it may be that the font you want is not available. HP and other lasers will default to courier if a font is not available
• Printer prints italic characters where one expects lines or other line draw characters (for example, in the axes of a graph). Usually this means that the printer is set to Epson character set instead of IBM PC Graphics. Check the manual for information o n configuring the printer to verify.
• Stylewriter prints true type characters in odd sizes with weird line breaks in Word 4 but not in other apps. Mac system needs MS Word 4 true type init (on Softserve).
• DMP prints with a "white line" horizontally through the characters. Bad print head--needs replacement.
• Laser printer prints with a black streak vertically through the paper. Needs cleaning, or the main drum is scored and needs service. You can try to clean the printer by opening the cover, removing the toner cartridge. Then look for a panel (usually hot!! !) under which there is a long thin wand with cotton along one side. If this is blackened, it needs replacement. Also, sometimes cutting back on the toner setting helps removed streaks.
• Postscript errors may be reported a variety of ways. Appletalk printers bounce the error message back to the Finder or Print Monitor. Many printers will generate error codes to the lcd panel, or print out the error message. If you get a postscript errors, you can try the following:
  1. Choose a different postscript driver if one is available.
  2. Try printing the document in smaller sections. Often a particular formatting command, or a certain graphic element will be the cause of the error. If you find the particular troublemaker, you can either work around it, or try using a different method o f converting or creating it.
  3. Try to print to a non-postscript printer. Quickdraw printers, for example, use the same language as the screen on Macintosh, so if a Macintosh can display the file correctly to the screen, it can print it to a Quickdraw printer.
  4. If you get an offending command message, that sometimes indicates that a necessary subroutine has not been downloaded to the printer, or the driver downloaded it incorrectly. Try using a different driver.
  5. Cold booting the printer will sometimes help, as it clears the printer's ram of downloaded subroutines and fonts, thereby giving the processor more room to work with.

Typical Software Problems

Windows

Win 3.1 and NT/95 control printer access for all apps, and supports bitmapped fonts, postscript (with ATM) and True Type. Remember that DOS programs use their own drivers, and thus do not share the features supported in Windows. Win 3.1 use Print Manager to control background printing; you should disable this in a trouble shooting phase as it can become corrupted, and you will want to clear any stuck jobs therein. Windows will sometimes have trouble with true type fonts. Check the fonts control panel and try changing the settings controlling how truetype is handled. Windows 95/NT controls printers via printer object, check the settings there carefully.

You can also increase printer access with Windows using HP's Jet Admin software, which allows IP and IPX connections, and controls queue and port assignments. Make sure you get the latest version though.

Mac OS

The macintosh OS supports postscript, bitmap, and truetype fonts, and attempts to use the best option for the output device. For example, if the system has all three types available to it, it will use bitmapped fonts for the screen output. If a bitmap as a given size is not available,it will use a truetype font. If no true type font is available, it will resize a bitmapped font of another size. The final option is using a postscript font, but this is only available with third party software such as Adobe Type Manager. For printers, this procedure is slightly more complex. First the system tries to find a postscript font on the printer. If none is available there, it will try to down load a postscript font from the extensions folder. If there is no postscript t font there, the system tries to convert a true type font to a downloadable postscript outline. If these options fail, but font substitution (under File/Page Setup) is enabled, it will use a font of the same family, following the same search pattern out line above. If font substitution is not enabled, the system will raster an outline from a bitmapped font. The Mac OS also uses a background printer program, called Print Montior. If Background Printing is enabled in Chooser for the chosen printer, print jobs are spooled to the Print Monitor Documents folder in the System Folder. You should disable background printing if another print queue, such as a Novell queue is available.