The length of time between cleaning will depend on the usage of the printer. If the computer is under heavy stress, the technician will need to pay particular attention to the printer. Printer maintenance involves visually inspecting the printer for any debris that might hinder the performance of the printer components. The technician should look for dirt, dust, error messages, and paper jams during the visual inspection of the printer.

Preventive maintenance will not prevent all printer errors. Printers are intricate and delicate devices. There are numerous moving parts and each can potentially cause problems. Printers can fail in a multitude of areas.

A convenient troubleshooting and diagnostic tool is the capability of the printer to self-test. Printing a self-test page will help the technician isolate the location of the printer error. If nothing prints, check if the connections are correct, the printer is turned on, the paper has been properly loaded, and the printer is online. Also, verify that the printer is the default printer in the Control Panel. To select the printer as the default printer, right-click on the printer icon in the Control Panel.

Common Printer Errors 
The most common reason for printer problems are broken printer parts, cabling issues, parallel port errors, and outdated or bad drivers.

If the printer completes the self-test or prints double-spaced but does not print single-spaced, there might be a problem with the dipswitch setting, driver, or cable. If the dip settings are to be changed, make sure the power is turned off. Serious damage can occur within the circuitry if the power is left on.

If the printer shuts down intermittently, it could be having problems with its thermistor. A thermistor is used to keep the printer from overheating. The only way to repair this problem is to buy a new replacement part.

Troubleshooting paper jams is a common task for most technicians. The usual symptom is an error message or the paper is not advancing. The first step should be to check the paper loader for jammed paper or an overloaded paper tray. Clean any jammed paper and visually inspect the paper path for any obstructions. The printer could also be configured for the wrong paper tray. Verify that it is set to the correct tray. In rare cases, the paper feed motor might be "dead", in which case a new paper motor will be required.

Troubleshooting Ink Jet Printers
If an ink jet is not printing clearly or correctly, it might be experiencing problems with the print heads. The print heads work by spraying ink through tiny nozzles. When the print heads are clogged, they will not print correctly. Visually inspect the print heads for any debris that might be restricting the flow of ink. If the print head looks clogged, it will have to be cleaned. Print heads can be cleaned by the printer software (if available) or manually by the technician. The printer software might be capable of running a series of cleaning events. Right-click on the printer icon in the Control Panel to verify that the printer is capable of performing a self-cleaning test. Generally, print heads are cleaned manually by submersing the print head into a 1mm thick layer of denatured alcohol. Do not completely submerse the print heads. Only the pins should be submersed. Soak the pins for approximately two to three minutes. Remove from solution and carefully re-install the print head. After the print head is carefully attached to the ribbon cable, run a self-test to flush out any remaining ink. Repeat if necessary. After the print head is clean, apply one to two drops of light oil to the pins. Manual cleaning varies from manufacturer to manufacturer. Check the printer manual for instructions on how to clean the print heads.

If the ink jet printer says it is offline but it is connected, verify that the cables are properly connected. Most likely the cable between the computer and printer has been disconnected.

Troubleshooting Dot Matrix Printers
Dot matrix printers use a series of pins, which are located on the print head, to transfer ink to paper. These pins repeatedly strike the paper and over time can become clogged. Dust and ink can prevent the pins from functioning correctly. To resolve this problem, first unplug the dot matrix printer. Carefully remove the print head from the ribbon cable. While removing the print head, pay attention to how the print head is installed so it can be reinstalled properly. Next, soak the print head in denatured alcohol. Also, place the pins in the denatured alcohol and let stand for two or three minutes. Let the print head dry and then replace. Run the printer self-test without the ribbon attached to the print head. This will allow any excess or residual ink to be removed from the pins. Replace the ribbon after the pins are free of any excess ink.

If the characters are not properly aligned on the page, the ribbon cable might be misaligned with the print head. Verify that the ribbon cable and print head are properly spaced. Also, verify that the ribbon is advancing properly. If the problem still exists, the printer might be out of ink. If, after replacing the ink, the problem still exists, consult the printer manual to verify the proper printer control settings.

Troubleshooting Laser Printers
To efficiently troubleshoot laser printers, technicians must be knowledgeable of the components of a laser printer. This will help in order to isolate the problem. Table is a list of the most common laser printer problems.

Students can read more about troubleshooting printers, especially dealing with issues related to paper jams, in Chapter 9, "Printers and Printing".
 

Worksheet  (PDF, 7 KB)   Troubleshooting Printers