It seems as though printer problems occur only at the most inconvenient time—like when you have a deadline to meet and you’ve waited until the last minute to print the document.

The difficult thing about having a printer problem fixed down at your local computer store is that you probably don’t know whether the problem lies with your computer, the cable, or the printer. That means carrying in your computer, the cable, and the printer.

If you’d like to try troubleshooting printer problems on your own, you need a basic understanding of what goes on during the print process. You don’t have to know every detail of the design of the printer, the printer port, the printer driver, and the printer cable, but a little background information may help you find and correct the problem.

From your computer to your printer
One of the most common sources of printing problems is the printer cable. Cable problems are also the easiest to diagnose and correct.

If you examine the cable connecting the printer to your computer, chances are you’ll find a 36-pin Centronics connector on the end attached to the printer and a 25-pin D-type connector attached to the parallel port of your computer, which is called the printer port or LPT port.

The default printer port for most software is usually LPT1. If there are multiple parallel ports in your machine, they will be designated LPT1, LPT2, and so on.

There have been several enhancements to the capabilities of the parallel port since the days of the IBM XT machines. The original ports were unidirectional, which meant that they could send data but couldn’t receive it. They could, however, receive status information from the printer. These signals—such as paper out, busy, or error—control the flow of data to the printer.

Your printer has a data buffer that receives the data from the computer and supplies it to the printer at a rate that the printer can accept. The signals from the printer to the parallel port turn on and off this flow of data.

Each of the 25 conductors on your printer cable is important to the proper operation of your printer. A bad cable can produce all sorts of strange printing problems.

You should consider several issues when examining a printer cable. Normal wear and tear can damage one or more of the wires or pins in the connectors. (The Centronics connector seems to be more vulnerable to damage than the D-type connector.) Look for obvious damage to the cable and its connectors, although a bad cable will often show no signs of damage. Make sure that the cable isn’t passing near a source of electrical interference. The longer the cable, the more susceptible it will be to electrical interference.

If you have a late-model computer with a parallel port that supports ECP/EPP modes and you use a modern, fast printer that can take advantage of it, be sure to connect them with a high-quality IEEE 1284 compliant cable. The price will seem high for a printer cable, particularly when you compare it with the lowest priced cables, but it’s worth the money.

The fastest way to troubleshoot a cable with no obvious defects is to substitute a known good cable and see if the problem goes away. Or, you can place your questionable cable on a system that is having no problems, to see if your problems follow the cable.

Printer driver problems
The printer driver that you installed when you set up your printer tells your parallel port how to manage the data being sent to the printer. Different makes and models of printers require specific software to effectively manage their particular features.

One of the most common printing problems is that an incorrect or defective printer driver is being used. This can result in all sorts of strange gibberish on the printed page. If you selected the wrong printer driver for the printer you are trying to use, you may need to purge the print jobs that are hung up in the spooler as well as reset the printer to remove any bad data that remains in its buffer.

Purge the print jobs first. You can do this in Windows 95/98 by clicking on Start, Settings, Printers, and then clicking the icon for the appropriate printer. When the window for the printer opens, click Printer in the upper-left corner and then click Purge Documents.

Now reset your printer to remove the last traces of the “poison” still in the printer’s buffer.

It’s also possible that you have the correct printer driver but that it isn’t configured properly for the amount of RAM installed in your printer. If the driver is set for more RAM than the printer actually has, an overflow can occur. This might go unnoticed for a long time. It may appear only when you have a large print job or pages with lots of graphics.

Get the latest drivers
Sometimes there are known issues with a printer driver that crop up only under certain circumstances. The best insurance is to go the Internet and download the latest printer drivers for your operating system and printer.

Whenever you install a printer driver, make sure that all of the setting options are correct for your individual printer. This not only includes the RAM settings, but also settings like the source tray for the paper, the paper size and orientation, the timeout settings, and the print resolution.

Selecting the correct port type
Another possibility is that your parallel port settings are incorrect in your CMOS setup. This is assuming that the parallel port is integrated on the motherboard. First, see if Windows is giving any indication of a problem in Device Manager. To do this, click Start, Settings, Control Panel, and then double-click on the System icon. Now select the Device Manager tab. If there is a problem with the on-board parallel port settings, you will see a flag on the device, indicating a discrepancy. Highlight the parallel port and click Properties to view the device status. Next, click Resources to check out any resource conflicts.

It’s quite possible that when you last installed a component, you created a resource conflict that didn’t appear until later when you tried to print. If a conflict is indicated, try changing the resources that the offending device is using.

Testing the parallel port
Diagnostic software such as CheckIt or Norton Utilities can test the integrity of your port by using a loop-back plug attached to your parallel port. This type of test can also be performed on your serial ports. Be sure that you use a loop-back plug compatible with the testing software. This is because manufacturers utilize different loop-back wiring schemes in their products.

The loop-back plug test may not find every parallel port problem, but if it does indicate a problem, it’s probably accurate.

If you find a bad parallel port on a motherboard with integrated peripherals, you can disable the port in the CMOS Setup and install an add-on parallel port if you have an unused ISA slot. But check prices before you do this. You may be able to replace your motherboard with a new one for very little more than the cost of a new parallel port card.

Check the CMOS
If you find no resource conflicts, try changing the port type in the CMOS. Run the CMOS Setup program, open the Integrated Peripherals menu, and select the parallel port type settings. Press [F1] to view the default setting. If the default setting isn’t specified, try changing the mode to the default. You can also try setting to another value the memory address that the port is using. Start with the default setting and then restart the computer and try printing again. Windows will probably find what it considers new hardware and install the proper software during the start up process. Note: This is the process I followed on my computer. However, since every CMOS is different, your system may require you to change the port type in a different manner. Documentation may accompany your computer or motherboard (if it was custom built).

Process of elimination
If you’ve checked the cable, the printer driver, the parallel port settings, the integrity of the parallel port, and the possibility of resource conflicts, about the only thing left is the printer itself.

There are a lot of things that can go wrong with a printer. If you’ve eliminated all other possibilities and have decided that the printer is the culprit, consult the manual that came with your printer for user-serviceable items.

 The new generation of inkjet printers has the capability of printing at a very high resolution. To achieve this resolution, you must choose from a variety of high-quality papers available. If you’re using standard quality inkjet paper, there is no benefit from choosing a very high resolution. The print speed will be greatly influenced by the resolution you select.

Don’t try to use the paper designed for an ink jet printer in your laser printer. This paper is not compatible with the high temperatures present in a laser printer. You can create a real mess inside your laser printer by doing so. (Guess how I learned this.)

Another lesson I learned the hard way concerns letterhead paper and the envelopes that have a preprinted return address. Be sure that the ink used on the letterhead and the envelopes is approved for laser printers. Some of the more decorative inks will melt on the rollers of the printer and then transfer to the remainder of the pages as they pass through the printer.

If your laser printer has begun to print pages with some of the areas of the page appearing lighter than the rest, your toner cartridge may be a little low on toner. To get the maximum life from a toner cartridge, make sure that the remaining toner is evenly distributed in the cartridge. Do this by removing the cartridge from the printer and, while holding it in the same orientation that it rests in when installed, gently rock it back and forth, tilting it about 45 degrees in each direction. The object is to make toner available over the whole width of the drum. Be careful not to shake the cartridge too vigorously as it takes very little spilled toner to make a big mess.

While you have the printer open and the cartridge removed, take the time to clean it out. Follow the directions in the owner’s manual carefully so as to not damage anything.

Repairing printers

If it turns out that that a major component of your printer needs to be replaced, you may find that the new part costs nearly as much as a new printer. If you use a repair service, ask for an estimate of the repair costs before they proceed.