Electronic troubleshooting is a strange pursuit; it is an activity that falls somewhere between art and science. Success in troubleshooting depends largely on a thorough, logical troubleshooting approach and the right type of test equipment, as well as an element of intuition and luck. This article shows you how to evaluate and determine printer problems, locate technical data, and present a series of printer service guidelines that can ease your work.
The laser printer service & troubleshooting cycle
Define the laser printers symptoms
Identify and isolate printer parts
Repair or replace parts parts
Retest the laser printer
Regardless of how complex your particular circuit or system might be, a reliable troubleshooting procedure can be broken down into four basic steps as shown in Fig. 4-1: (1) define the printer's symptoms, (2) identify and isolate the potential source (or location) of the problem, (3) replace or repair the suspected component or subassembly, and (4) re-test the system thoroughly to be sure that you have solved the problem. If you have not solved the problem, begin again from step 1. The procedure is a universal procedure you can use for any troubleshooting-not just for laser printers.
Define the laser printer’s symptoms
Sooner or later, a laser printer is going to break down. The problem might be as simple as a sticky gear or as complicated as an extensive electronic failure. However, before you open the toolbox, you rust have a firm understanding of the symptoms. You must do more than to simply say, "It's busted." Think about its symptoms carefully Ask yourself what is (or is not) happening. Consider when it is happening.
If this installation is new, ask yourself if the computer is set. up properly, or if the right cables are being used, or if DIP switches are set up correctly. If you have used your laser printer for a while, do you remember the last time you cleaned and lubricated it? Is the print light, dark, or completely missing? Is the paper advancing freely? By recognizing and understanding your symptoms, you will find it easier to trace a problem to the appropriate subsection or components.
Use your senses and write down as many symptoms as you can-whatever you smell, see, or hear. Writing symptoms might sound tedious now, but when you are unto your elbows in repair work, a written record of symptoms and circumstances will keep you focused on the task at hand. Writing symptoms is even more important if you are a novice troubleshooter.
Identify and isolate laser printer parts
Before you try to isolate a problem in the laser printer, first be sure that the printer is, in fact, causing the problem. In many circumstances, printer problems will be obvious, but there are some situations that might appear ambiguous (no print with power on, erratic printing, not enough contrast, etc.).
Always remember that a printer is just a subsection of a larger system including your computer, laser printer, and interconnecting cable. Especially in new installations, a computer failure, software incompatibility, or cable problem might be causing your symptoms.
An easy application of the universal troubleshooting procedure follows. Once you have carefully identified your symptoms, isolate the printer. You can isolate a printer by removing it from its communication cable. You can replace it by testing on another computer system with a working printer (one that you know is working well).
A friend or colleague might let you test your printer on their computer system. Because various computers can be set up to communicate in different fashions, you might have to alter the internal settings of your printer to match those of the working printer.
When printing from an operating system such as Microsoft Windows, you might have to select and configure a new printer driver to support your printer. If your printer exhibits the same symptoms on another computer, there is an excellent chance that the problem is within the printer.
You can then proceed with specific troubleshooting procedures. If, however, those symptoms disappear and your printer works properly, you should suspect a problem in your computer, software configuration, DIP switch settings, printer driver, or interconnecting cable.
Another test is to try a working printer on your computer system. As before, you might need to select another printer driver to operate the working printer properly on your existing system. If another printer works properly, it verifies that the computer, software configuration, and cable are intact.
If a working printer fails to work on your system, check the computer communication interface, software settings and interconnecting cable. Complete this check in addition to testing your questionable printer on another system.
When you are confident that the printer is at fault, you can begin to identify any possible problem areas. Start at the subsection level. You might recall from previous articles that a laser printer consists of several major subsections. Your printer fault will be located in at least one of these subsections or subassemblies. The troubleshooting procedures in previous articles will aid you inn deciding which subsections are at fault.
Once you have identified a potential problem, you can begin the actual repair process In many cases, your repair will involve replacing a defective subassembly For skilled technicians, the repair might include tracking a defect to the component level.
Repair or replace laser printer parts
Once you have an understanding of what is wrong and where to look, you might begin the actual repair procedures that you think will correct the symptoms. Some procedures require only simple adjustments or cleaning, arnd others might require the exchange of electrical or mechanical parts. All procedures are important and should be followed very carefully.
Laser printer parts are usually classified as components or subassemblies. A component part is the smallest possible individual part that you can work with. Components can serve many different purposes in a printer. rollers, solenoids, gears, motors, and integrated circuits are just a few types of component parts. Usually, components contain no serviceable parts-the components themselves must be replaced.
A subassembly is composed of a variety of individual components. Unlike components, a complete sub assembly serves a single, specific purpose in a printer, but it too can be repaired by locating and replacing any faulty components. Repairing a defective subassembly simply by installing a new one in the printer is certainly an acceptable solution.
All technicians must make the cost/performance tradeoff when performing a repair. Component parts are much less expensive than subassemblies, but components are often specialized and can be difficult to get. You also might need test equipment and time to troubleshoot to the component level. Replacing subassemblies is faster and easier than tracing component faults, even though assemblies are more expensive.
Subassernbly service makes good sense for individuals who lack the time, experience, or test equipment to worry about component-level faults. Replacement electronic components might often be purchased from several different sources, but keep in mind that many mechanical parts and fittings might only be available through the manufacturer or distributor.
Many of the mail-order companies listed at the end of this book will send you their complete catalogs or product listings at your request. Going to the manufacturer for subassemblies or components is often somewhat of a calculated risk-they might do business only with their affiliated service centers, or refuse to sell parts directly to consumers.
If you find a manufacturer willing to sell you parts, you must often know the manufacturer's exact part number or code. Remember that many manufacturers are ill equipped to deal with consumers directly, so be patient and be prepared to make several different calls.
During a repair, you might reach a roadblock that requires you to leave the printer for a day or two (or longer). The delay is typical when you have diagnosed a failure and are waiting for parts. Make it a point to reassemble the printer as much as possible before leaving it. Place any loose parts into plastic bags and seal them shut.
Reassembly will prevent a playful pet, curious child, or well-meaning spouse from accidentally misplacing or discarding parts while the printer sits on your workbench. Making loose parts secure is twice as important if your workspace is in a well traveled or family area. You also will remember how to put it back together later on. Make notes to remind yourself what parts go where. Take photos with your smart phone.
Re-testing the laser printer
When repair is complete carefully reassemble the laser printer and test it before connecting it to a computer. Run a thorough self-test to check printer operation. The self test checks the image-formation system, paper pickup and registration, fusing assembly, power supply, and much of the printer electronics. If symptoms persist you will have to re-evaluate them and narrow the problem to another part.
If normal operation is restored (or significantly improved), test the printer with a computer and interconnecting cable. When you can verify that your symptoms have stopped during actual operation, the printer can be returned to service.
Do not be discouraged if the printer still malfunctions. Simply walk away, clear your head, and start again by defining your symptoms. Never continue with a repair if you are tired or frustrated-tomorrow is another day. For technicians troubleshooting to the component level, also realize that there might be more than one bad component to deal with.
Remember that a laser printer is just a collection of assemblies, and each assembly is a collection of components. Normally, everything works together, but when one part fails, it might cause one or more interconnected parts to fail as well. Be prepared to make several repair attempts before the printer is repaired completely.
Gathering the laser printer technical data
Technical information is perhaps your most valuable tool in tackling a printer repair. Just how much information you actually need will depend on the particular problems you are facing. Simple adjustments and cleaning might be accomplished with little or no specific technical information (except your own observations and common sense judgment), but complex electronic troubleshooting might require a complete set of schematics.
Parts lists will be needed to order new mechanical components and all types of subassemblies. More intricate repair procedures generally need more comprehensive technical literature. Luckily, there are some avenues of information. Your user's manual is always a good place for basic printer information.
A user's manual describes how to set up and operate the printer, outlines its important specifications and communication interface, and points out its major assemblies and controls. If you are unfamiliar with the printer or unaccustomed to changing its configurations, a user's manual can keep you out of trouble.
Some user's manuals also present a short selection of very basic troubleshooting and maintenance procedures, but these are almost always related to the printer setup and operation-not to its internal circuitry or mechanics You can find technical information on many individual components on data sheets published by the component manufacturer.
For example, if you want a pin diagram of an IC manufactured by Motorola, you could refer to a Motorola data book containing information on that particular component. The data book tells you what the part is, what it does, what purpose each pin performs, and what its electrical specifications Are.
Although data books bear no direct relationship to your particular printer, they can give you much insight on the purpose and functions of individual components However, if you intend to pursue detailed electronic repairs, you will need a set of schematics. A complete set of schematics can quickly and efficiently guide you through even the most complicated printer.
A manufacturer's service or repair manual also offers parts lists and mechanical diagrams that clarify how the printer is assembled. Your printer manufacturer can be a key source of information, but not all manufacturers are willing to sell technical information to individuals or private organizations. Third party parts remanufactures like Metrofuser a great source for part identification.
Other Helpful HP LaserJet Printer Support Resources
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