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HP Laser Printer Technician Basics

Updated: Jul 8, 2019

Essential tips for entry level HP laser printer repair technicians starting out.

This article is designed for new techs, as a very basic introduction to electronics and electricity, and to tools, instruments and their use.

Essential tips for entry level HP laser printer repair technicians starting out.

REQUISITE SKILLS To become a laser printer technician, you need to have certain skills and tools. Briefly stated, you need to know about: 1. Which tools are essential and which are nice to have. 2. How to use the tools. 3. Test equipment. 4. Electricity. 5. How to use a multimeter.

Laser Printer Tools and Use

Ninety percent of all repairs can be accomplished with nothing more than three tools: (1) a magnetized 6-inch, #2 Phillips head screwdriver; (2) a magnetized, small-bladed screwdriver and (3) a pair of needle-nose pliers.

That's it-only three primary tools. However, you will carry a whole lot more with you in your toolbox. The toolbox itself is worth discussing.

Early techs in this business were copier techs looking for opportunity. Understandably, they came to our business with their briefcase-style, 400-tool kits. While that works fine for the copier industry, it doesn't relate to the printer business.

Copier techs started with a different philosophy. Their copiers broke a lot. That meant customers were inclined to question the quality of the machines and that technicians had to spend a great deal of time at customer sites.

Early in its history, copier guys set a pattern for its techs. They decided that, to combat questions of quality, they would establish an inordinate standard of competence and professionalism in their technical field force. If the machines were going to fail often, the technicians weren't. Machine failure was blamed on the incredible nature of the machines and the extraordinary demands placed upon them. The techs were dressed and equipped like investment bankers.

When a machine broke, a team of three-piece suits equipped with attache cases (cleverly converted to carry an incredible array of tools and hardwares) descended upon it and proceeded to return it to service with all the drama and professionalism exhibited in a hospital operating room.

Customers were impressed by this. Previously, service personnel had been "blue-collar" types, who earned a blue-collar reception on site.

The items they fixed were generally low-maintenance, and their visits to the workplace uncommon. The copier man, however, was in the office quite frequently, sometimes weekly. It was important that he meld with the landscape and attract as little attention as possible. If any attention were to be drawn toward him, it was critical that it be positive in nature.

This explains the ridiculous attache toolkit, and the more ridiculous posturing that had technicians dressing like bankers in order to service machinery that was potentially as dirty as an automobile engine or undercarriage. It was customer driven and produced an image that the manufacturers wanted for their equipment.

Beyond that, the attache kits were no impediment to servicing the equipment; they kept the tools well organized and were easy to transport. In most offices, the "copier room" offered plenty of space to open an attache and leave it out while the repair was being accomplished.

Although it was predictable that copier techs would carry their successful culture into the laser printer business, it was wholly inappropriate to do so. When considering maintenance, three major differences separate printers from copiers, and argue for a different service "culture"

  • Printers are much more reliable. They seldom fail.

  • Printers can be repaired quickly. Printers are integrated into the office landscape, unlike copiers, which tend to have a dedicated room or space.

Laser Printer Increased Reliability Who knew that laser printers would be so reliable that people would come to think they would never break? Printer reliability leaves the service industry with a sustainability problem. People who don't balk at monthly maintenance agreements on their copiers are now reluctant to spend money maintaining their laser printers often preferring replacement to repair.

Had the industry organized early and anticipated this, we could have moved quickly to establish programs like preventive maintenance that would encourage owners to better maintain their machines.

As it is, customers tend to defer maintenance. Damage that might have been prevented results in the early replacement of the machines While the technical support for our industry came from the copier industry, purchasers of laser printers are the same people who buy the computers, not the copiers.

Consequently, there is a constant and undeniable pressure to declare printers functionally obsolete and replace them with models commanding greater features and benefits. This is the pattern of the computer industry, where a product's life is often measured in months rather than years. Printers, on the other hand, enjoy greater longevity, trapping them in a no man's land" between computers, which change monthly, and copiers, which hardly change at all.

Given printer reliability, we don't have to apologize for a technician's presence on site. Indeed, we can herald it. He doesn't need to look like all the other guys in the office; he just needs to be professional. He doesn't have to wear a three-piece suit, and his toolkit doesn't have to look like it contains a stack of Wall Street Journals.

Because printers fail so infrequently, and because technicians are seen so rarely, their arrival is eagerly awaited. When a copier is down, people go back to their tasks, postponing copying or sending it out. But a printer failure is a much more personal problem. Because so many are desktop appliances, a printer's failure generally means its user is "out of business.

When a HP laser printer technicians gets there he may be received more like a messiah than a repairman. Customers are prepared, frequently pre-educated, to like him. No gimmicks are required to pass him off. His approach can be utilitarian and functional, because what the customers do expect is a very rapid return to extraordinary reliability.

SPEEDY HP Laser Printer Repairs

Take the covers off a freestanding copier, and you may be baffled by the confusion of wiring harnesses, brackets and integrated assemblies. Copier maintenance is a lot of work. The average copier tech is a hero if he completes four calls a day, including simple ones such as cleaning optics or replacing an OPC. Give him a tough problem, and he's easily there for a half-day, sometimes longer.

Laser printers are vastly different. The average repair is about 20 minutes, cover to cover. Changing a printer fuser takes five minutes. Preventive printer maintenance requires 30 to 45 minutes, but generally requires some customer interaction. The average printer tech can complete six calls a day, and may work on as many as 8 to 10 machines on a busy day.

It isn't difficult to reward the customer's need and expectation of a fast repair. The machines come apart easily and are repaired quickly. All that's required is knowledge and experience. Once again, gimmicks and posturing are unnecessary and unproductive. Training and preparation are what will produce the greatest customer appreciation. You must have the right tools and know how to use them. You must understand the machines and know how to fix them.


This is the factor that argues most strenuously against the attache toolkit. While copiers are generally huge machines sitting on the floor, or on freestanding cabinets, printers are generally tucked away in every nook and cranny available. Then, customers pile stuff around them and on top of them.

There is no extra space to work. Frequently, this means that machines will rest on top of file cabinets or sit on specially designed more than 30 inches off the floor. You may be carrying perches the attache toolkit, but the bottom line is, you need something to stand on.

I carried one of those attache kits my first year in the business. Although it helped me keep track of the tools, I kept finding machines in the most awkward places, where it wasn't convenient to use an attache kit.

Sometimes I would spend twice the time required for the repair just to relocate the machine so I could work on it. Looking back, I figure it cost me $200 to $500 a month to carry my "copier kit." (I still have the case, or rather, know where it is. I long ago cannibalized the tools from it and gave it to my grandson to play with.)

I now carry a big Rubber Maid box that doubles as a footstool. I carry it and a plastic milk crate full of parts on a rolling luggage cart that I can maneuver through crowded office interiors. Part of the learning curve in this business has to do with the logistical problems of getting the most done in the least time with minimal disruption of the normal office routine.

Essential HP Printer Repair Tools

  1. Phillips head screwdrivers. Actually, it would be better if you went to Japan to buy them. There is a substantive difference between Japanese and American screws. (Just because it says "Made in Japan" doesn't mean it's a Japanese screwdriver.) There are distinct differences. An American Phillips head is cut deeper and at a greater angle than the Japanese design. The Japanese model has a shallower bevel, made to work well with Japanese screws. An American-design screwdriver tends to hollow out the heads of Japanese screws. In addition to the mandatory 6-inch # 2 Phillips head, I also carry a #1 Phillips, a 4-inch # 2 Phillips and a stubby #2 Phillips. Incredibly, all three are essential for changing a Fuser in the original LaserJet printer (but in none since), You may get it out without one or another of them, but you'll wish you had brought the whole set.

  2. Needle-nose pliers. You'll need two or three sets of varying length and thickness. I carry three. One is very, very long and thin, for difficult detail work. If it were a hummingbird, my largest one would be an owl, with beaks that vary accordingly. Some work is tough and strength-related. I also carry a regular set of pliers and a couple of small vice-grips.

  3. Bladed screwdrivers. You'll need them on occasion. I carry three of these, too. One is just your average household screwdriver. The second is the kind that computer stores or exhibitors give away or sell cheaply. It's the size you need for taking the little slot covers off a desktop computer. The third is a micro driver. (The smallest bladed screwdrivers I carry are really a set of jeweler's screwdrivers that I use more as chisels and digging tools than as screwdrivers.)

  4. Nutdrivers. These are sometimes helpful, as well, but more for the occasional odd-ball machine.

  5. Magnetizer/demagnetizer. I keep one in the bottom corner of my tool box. It's made of two horseshoe magnets strapped together with durable elastic or copier you're called upon to look at than for laser printers bands, creating a hole in the center. Plunge your screwdriver through the hole and it becomes magnetized. Slide it against the side and it becomes demagnetized. This essential, irreplaceable tool is made by Stanley and available a Home Depot. A more powerful, plastic-bound model is available from Ames yet a higher price. The added benefit of having a magnetizer/demagnetizer in the bottom of your toolbox is that it will grab and hold all the loose screws in there.

  6. Flashlights. I have two small flashlights, and one wraparound holds-itself flashlight. Make sure you have an extra supply of batteries.

  7. Odds and ends. I carry some odd tools, too. My favorite is a dental pick which I use for a spring hook, a screw straightener, a contact tweaker and any number of odd chores. I also have a pivoting 2 mm Allen screw wrench with a (2 mm is the size of the screws at the clutches holding the boss the fixed end of the Clutch Assembly to the axles.)

Using Printer Service Tools After Years of teaching classes, We've observed some tool-use techniques so failure prone that I must offer a little advice on the subject. Screws used in most machines are soft and easy to strip or hollow out. As stated before, this is complicated by the fact that, for most techs, the bevel of the screwdriver fails to match the bevel of the screw. With that in mind, a few precautions are in order.

Using laser printer repair tools

When removing a screw from an HP printer

  1. Hold the screwdriver perfectly vertical, in line with the shaft of the screw.

  2. Press very, very firmly before torquing the screw.

  3. Maintain the vertical character of the driver while you break the screw's hold.

  4. If you don't feel it immediately breaking loose, stop; you may be hollowing the head.

  5. Continue again with maximum vertical pressure on the screw.

When tightening a screw:

  1. Tighten screws, but don't crank them down. (This happens at every class. Some guy wants to tighten the screws so they won't budge without benefit of an impact wrench. This is truly unnecessary.)

  2. Maintain the driver in true vertical position. To speed things up, after the screw has started turning, turn the shaft of the tool with your fingers instead of the handle. With my Japanese tools, the handles are large enough and heavy enough to act as flywheels after I begin turning the shafts with my fingers.


While hand tools are limited and you don't need anything I haven't listed, there are some special tools you will need or may want to have.

  1. Multimeter (virtually essential). You'll use it to do several things, the most important of which are testing for continuity in a circuit and measuring the current on a circuit. Buy digital or analog, either is fine, but try to find one tna makes a nice tone on continuity tests.

  2. Vacuum (essential). Make certain it's one for toner particles or they'll blow right through the filter. Change the filter periodically (actually, you can dump it out and keep using it for awhile) and it should last you forever. Use this to clean out large, visible accumulations of toner before you do anything else. (Ames, various others)

  3. Ground Test (optional). You can get along without this, but it's cheap and a good way to determine if your customer has properly grounded outlets.

  4. Anacom Smartbox (optional, but recommended). This is essentially a stupid computer that can only send pre-established print commands to the subject printers. You have to have one, or a laptop computer, if you're going to be effective at all on communications problems.

  5. Laptop or Notebook Computer (optional, but highly recommended). Better to have a real computer. Your customer is more readily convinced of your diagnosis if his printer works driven by a laptop than by the mysterious Smartbox. Besides, you can use it other ways, as well. Look for a used one, starting at $300.



Tools are important, but you will need supplies as well. Again, there are essentials and "nice-to-haves." I carry an equivalent of each of the following items:

  1. Rubber Cleaner. I use a solvent made from commercial blanket wash (used to clean offset printing sheets or "blankets"), and a small amount of Citrus Solv, a solvent cleaner made from orange and lemon peels. (At my classes, I refer to this as "Miracle Mike's Magical Elixir." That's a joke, but it really is powerful stuff. Rubber must be cleaned by a "friendly" solvent. Alcohol will dry it out and Fedron is a toxic cleaner, better suited to typewriter platens.) The blanket wash I use is called Litho Clean Systems Wash (part 101, from Hurst Graph- ics). I also use a spray product called Rubber Roller Cleaner (from L&M Manufacturing in Miami, Florida). I don't think it's quite as effective as the blanket wash, and it's far more expensive.

  2. Wipes. When I first started in this business, the wipes I used were paper towels from the men's lavatories in the office buildings I was visiting. They were about the right size, and they folded to fit in my case. Best of all, they were free, and conveniently located at my clients' installations. They were also generous lint depositors. But the worst problem was image; the client knew exactly what I was using. The only thing I've seen that made a less positive impression was a guy using pink shop rags. I now use white polyester and acrylic rags from Ames Supply. They look more like a specialty tool.

  3. Steel Wool (0000). For contact surfaces that must be cleaned, but not seriously abraded, fine steel wool is the best choice. Sprinkle it with blanket wash before using.

  4. Printer Cover Panel Cleaner. Case cleaning is usually best done with Formula 409, or a similar cleaning compound. Of course, you don't want to leave it in the 409 bottle. Change the spray bottle so your customer won't know what it is. Your customer has no respect for anything he can buy himself and, if you use something he can get, it diminishes your professionalism in his mind. You don't want him thinking, "I could have done that.

  5. Isopropyl Alcohol. Use this to clean some metal surfaces. Caution: Do not use it on rubber rollers or other rubber feed parts. It will cause them to dry out and harden.

  6. Canned Air. I use this frequently because vacuums, by themselves, do a poor job of removing debris. Canned air is best used in conjunction with a vacuum. The canned air stirs up the debris; the vacuum catches it when it's airborne.

  7. Water. Occasionally, you'll need water, so find a spray bottle to haul it around in. If you're ever called on to clean an ink jet printer, you'll use it to clean up the water-soluble ink. Plain warm water works best. Easy on adding soap; it's hard to rinse off.

  8. Emery Boards. Sometimes an exit roller gives you problems, and you don't have a replacement with you. An emery board is the easicst way to clean and restore the rubber that's still there.

LASER PRINTER ELECTRICAL PRIMER Atoms are electrically balanced collections of tiny charged and uncharged particles. Within any atom, there are electrons with a negative charge, and protons with a positive charge. There are also various other particles, but they have nothing to do with learning anything about electricity.

If you were able to gather these charged particles, and if they were large enough for you to see, and if you could tell them apart., you'd find that particles with the same type of charge repel each other, while particles that have opposite charges attract each other.

The simple law that emerges from this observation is "opposites attract, likes repel." You have noticed this phenomenon innumerable times. Sometimes, when you pull clothes out of the dryer they cling to one another, then make the hairs stand up on your arm. This is an example of charged particles gathering on the various surfaces. We used to take balloons and rub them against our hair. It made our hair stand up and let us "stick" the balloons to the wall. We weren't creating a static charge, we were merely released the potential charge existent in the particles present. Because the charges in an atom always equal zero, that is, they cancel each other out, the charges we released do the same thing. If we brought all the charged particles released back together, they would cancel each other out.

Without laboring these examples further, I hope you can see why we can speak of using positive and negative charges. These "labelled" charges represent what is called "Direct Current," or DC electricity, the type most commonly used in electronic equipment. For example, many printers have three voltages: 24 Volts DC (24 VDC), 5 VDC and -5 VDC.

Of course, the incoming power is different. We start with 115 to 120 Volt of AC (Alternating Current). Alternating current is produced by some form of generator. Just as charges in an atom equal zero, the alternating currents coming from your wall outlet balance each other off.

Alternating current actually alternates between positive and negative. In a laser printer, AC current is used only to power the Heater Lamp in the Fuser. All other functions are driven from DC power. That's the function of the DC Power Supply. It takes AC power and transforms it to DC power, giving us our three primary voltages for later use and transformations. That's why the key component of any Power Supply is called a transformer.

Just as we used static electricity to make our hair stand up or get a balloon to stick to the wall, the laser printer creates high-voltage positive and negative charges in order to mOve toner. These charges are called static because, unlike currents, they stay with the elements they are conducted (or convected) to and bind or repel them from other objects.

Electricity is more commonly used in currents than in static applications. AC power is what we're most familiar with. Whether it's a hair dryer, a television set, allows the electricity to return, as well. The concept of current describes electricity or a laser printer, you plug it into the wall. This gives you a source of electricity and moving through a circuit, then returning.

Think of electricity as water. Think of the "work" that electricity does as little paddle wheels. To do the work, you have to move the water over the paddle wheels Because the water doesn't disappear, you must contain it and allow it passage to the next wheel, and so on, until it comes back to the end of its circuit.

If you were to divert the water at some point, the paddle below that pont wouldn't turn the wheel and the work wouldn't be done. You would be "breaking the circuit." Electricity works much the same way. Unless there's a continuing path of conductors and working components, the circuit will do no work. It will be open. Open circuits are what exist on appliances before you turn them on. Throwing the switch closes the circuit.

For our purposes, a circuit can have only two properties open or closed. Once you learn how to determine this, you have half of the knowledge you need to be a master printer technician.

We've been talking about volts, as well. Volts are a measure of the ability of the electricity to move through the circuit-its ability to overcome resistance. It's not the same as measuring the power or strength of the electricity, but the two are inextricably related and can be expressed in the equation V = IR, where V is electromotive force measured in volts, I is the rate of flow of current in amps, and R is resistance in ohms.

If you re up on your simple algebra, you can see that if the voltage is fixed, increasing the resistance will lower the flow. Piggybacking on our water example, think of water through a hose, where V is the pressure, R is the resistance (including the diameter of the hose), and I is the amount of water moving through the hose.

In fixing laser printers, you'll encounter a few instances where you might need to measure resistance, and several where you need to measure electromotive force, or voltage. I have never needed to check the amperage in a circuit.

Using Multimeters With Laser Printers

A Multimeter is used to measure electrical properties. You can buy a terrific one for than $100. It comes with two wires, a red one and a black one, called leads. For the two functions we're going to talk about, you will need to plug the red lead into the jack (hole) marked "+" and the black one into the hole marked "-"or COM." Doing so allows you to create your own simple circuits with the meter.

The Multimeter will have two primary controls (check the book that comes with the Multimeter for specifics). One control lets you select function, while the other should set sensitivity or scale. Better meters have floating scales and are extremely sensitive. For instance, if you wanted to measure the voltage of a wall outlet, you would set one dial to AC V, and the other to the lowest setting above 120 (in the case of my meter, it would be 300). Then, you'd boldly stick the ends of the exposed leads into the outlet, being careful to hold the leads by the handles!

Measuring Printer DC Voltage To measure the DC voltages, remove the cover. You will expose a connector. Set the meter to DC V, and the sensitivity to the lowest setting above 24 (on my meter, that would be 30). Touch the black lead to the frame of the printer or the metal bottom panel, and touch the red lead to the pin you want to test. As you look at the connector, the pin in the bottom left corner should read 24 VDC. Move the red lead to the right two pins and it should read -5 VDC. Two more pins to the right, your measure should read +5 VDC.

I would suggest you attempt this as an experiment before you sally out to do repairs. If you become comfortable with this measurement, you will easily be able to do others.

Printer Fuser Continuity The most common need to establish continuity is related to Fusers. They are heated by a lamp or a ceramic heating element, they are prone to failure. To confirm that it is, indeed, this part that has failed, a continuity test is necessary. Most meters require you to switch the main switch to continuity setting. This is because, unlike the other tests where you are measuring some electrical property in a circuit (measuring the circuit's electricity), this time you are sending electricity through the circuit to see if it will return.

On most meters, after selecting "CONTINUITY" on the main on/off switch, you must then set the function switch to K2. There is no sensitivity setting Touch the leads to each other and you complete a circuit. The result from the meter should be an audible tone.

The same thing would happen if you ran from one lead to the other that Fuser Lamp, you do the same thing. You place a lead on each of the wires leading to the lamp. If you get no tone, the lamp or FFA is blown. A tone, of course indicates that the connection is functioning normally, and you need to look elsewhere for the reason it isn't heating.

IN CLOSING... If you find any of the material in this article difficult to understand, I would suggest that you attempt an independent, more in-depth study of the area that's giving you difficulty. Ideally, everyone coming to our printer repair training classes, or any training program relating to electrostatic office machines, will have mastered the concepts and ideas related in this article.

Unfortunately, I know that, of the dozen or so students coming to any one of our classes, less than half will understand how to use a Multimeter, much less be comfortable with electrical theory or computer interfaces.

If you're planning on taking further training in this industry, learn as much as you can about the issues covered in this article, and don't be reluctant to ask your instructor questions about them. This information is the foundation that the edifice of future learning (and the rest of this book) is based upon.

On the other hand, don't think that you need to know how to read circuit diagrams and calculate circuit values to be able to work on and properly repair lase printers. Circuit design is not the job of a repair technician. Relate this to car repairs: A master mechanic will generally understand compression ratios and will be able to speak, sometimes eloquently, about every facet of the internal combustion engine, its electrical systems, transmissions, etc. Yet, he is hardly more qualified to change your spark plugs than a first-year apprentice. You don't need to understand radial-belt technology to change a tire.

Other Helpful HP LaserJet Printer Support Resources

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