This document provides an overview of laser printer technology. It discusses the electrophotographic printing process, describing the key components and systems involved like the charging, writing, developing, transfer, and fusing stages. It also covers troubleshooting techniques for addressing common issues in laser printers. Specific topics covered include mechanical systems, power supplies, image formation, electronic control packages, and safety procedures.
Wiring Diagram and Assembly Procedure of Washing MachineJhunalvin Santos
This document provides criteria and performance indicators for assessing a student's work in wiring and testing a washing machine motor. It lists categories such as accuracy of steps, workmanship, speed, proper use of equipment, and use of protective gear. For each category, it provides a rating scale from excellent to poor to evaluate the student's performance.
1) The document provides an introduction and outlines for a circuit analysis course. It discusses topics like resistance, current, voltage, and units of measurement.
2) It defines electrical resistance as the opposition to electron flow in a conductor. Resistance depends on the material's resistivity, length, and cross-sectional area. It also describes different types of resistors.
3) Formulas are provided for calculating resistance of circular wires as well as the relationship between resistance and conductance. Color coding schemes for fixed resistors are also explained.
Home networking refers to connecting multiple devices in a home, like smartphones, tablets, computers and smart TVs, to create a local network. This allows devices to communicate, share resources and access the internet. There are different types of home networking technologies, including wired Ethernet, wireless Wi-Fi, powerline communication and MoCA. Setting up a home network provides benefits such as sharing an internet connection between devices, easily transferring files between devices, sharing printers and streaming media. However, home networks also present security risks, reliability issues from interference and a limited wireless range depending on the home structure.
It is that branch of welding in which Electric current is used to produce the large heat required for joining together into firm two pieces of metals.
Electrical welding process fall into two main categories
RESISTANCE WELDING.
ARC WELDING.
This document outlines the syllabus and content for a basic electronics course. It discusses that the course grade will be based on midterm, final, and sessional marks. Sessional marks depend on behavior, participation, assignments, presentations, attendance, and quizzes. Contact information for the instructor is provided. Recommended reference materials are listed. An introduction to electronics and its role in daily life is given. The history of electronics from vacuum tubes to integrated circuits is summarized. Fundamental electronics components like resistors, capacitors, diodes, and transistors are defined. Band theory, intrinsic and extrinsic semiconductors, and PN junctions are explained conceptually. Students will have a homework assignment on electricity and magnetism
The document discusses various types of transducers including mechanical transducers, electrical transducers, LVDT, potentiometer, strain gauge, and resistance thermometer. It provides information on their working principles, construction details, applications, advantages, and limitations. The key points covered are that transducers convert one form of energy to another, electrical transducers are widely used for measurement as they allow remote sensing, and the selection of a transducer depends on factors like required accuracy, environmental conditions, errors, range, and resolution needed.
Automation involves delegating human control functions to technical equipment to increase productivity, quality and safety while reducing costs. It has evolved from simple pneumatic controllers to include programmable logic controllers controlled by software programs rather than physical wiring. Modern automation offers advantages like reduced space, lower energy use, easier maintenance and flexibility through software programmability. Sensors in the field send signals to control hardware like PLCs which execute control programs to operate final control elements. SCADA software then interfaces between field devices and control hardware for monitoring and operation.
This document provides an overview of key electrical concepts including:
- Voltage is the potential difference measured in volts that causes current to flow. Current is the rate of flow of electric charge measured in amperes.
- Ohm's law defines the relationship between voltage, current, and resistance in a circuit. Power is defined as voltage multiplied by current and describes the rate of energy transfer.
- Common circuit components are described including resistors, capacitors, diodes, transistors, integrated circuits, and how they are connected using printed circuit boards. Direction of electron and conventional currents are also discussed.
Wiring Diagram and Assembly Procedure of Washing MachineJhunalvin Santos
This document provides criteria and performance indicators for assessing a student's work in wiring and testing a washing machine motor. It lists categories such as accuracy of steps, workmanship, speed, proper use of equipment, and use of protective gear. For each category, it provides a rating scale from excellent to poor to evaluate the student's performance.
1) The document provides an introduction and outlines for a circuit analysis course. It discusses topics like resistance, current, voltage, and units of measurement.
2) It defines electrical resistance as the opposition to electron flow in a conductor. Resistance depends on the material's resistivity, length, and cross-sectional area. It also describes different types of resistors.
3) Formulas are provided for calculating resistance of circular wires as well as the relationship between resistance and conductance. Color coding schemes for fixed resistors are also explained.
Home networking refers to connecting multiple devices in a home, like smartphones, tablets, computers and smart TVs, to create a local network. This allows devices to communicate, share resources and access the internet. There are different types of home networking technologies, including wired Ethernet, wireless Wi-Fi, powerline communication and MoCA. Setting up a home network provides benefits such as sharing an internet connection between devices, easily transferring files between devices, sharing printers and streaming media. However, home networks also present security risks, reliability issues from interference and a limited wireless range depending on the home structure.
It is that branch of welding in which Electric current is used to produce the large heat required for joining together into firm two pieces of metals.
Electrical welding process fall into two main categories
RESISTANCE WELDING.
ARC WELDING.
This document outlines the syllabus and content for a basic electronics course. It discusses that the course grade will be based on midterm, final, and sessional marks. Sessional marks depend on behavior, participation, assignments, presentations, attendance, and quizzes. Contact information for the instructor is provided. Recommended reference materials are listed. An introduction to electronics and its role in daily life is given. The history of electronics from vacuum tubes to integrated circuits is summarized. Fundamental electronics components like resistors, capacitors, diodes, and transistors are defined. Band theory, intrinsic and extrinsic semiconductors, and PN junctions are explained conceptually. Students will have a homework assignment on electricity and magnetism
The document discusses various types of transducers including mechanical transducers, electrical transducers, LVDT, potentiometer, strain gauge, and resistance thermometer. It provides information on their working principles, construction details, applications, advantages, and limitations. The key points covered are that transducers convert one form of energy to another, electrical transducers are widely used for measurement as they allow remote sensing, and the selection of a transducer depends on factors like required accuracy, environmental conditions, errors, range, and resolution needed.
Automation involves delegating human control functions to technical equipment to increase productivity, quality and safety while reducing costs. It has evolved from simple pneumatic controllers to include programmable logic controllers controlled by software programs rather than physical wiring. Modern automation offers advantages like reduced space, lower energy use, easier maintenance and flexibility through software programmability. Sensors in the field send signals to control hardware like PLCs which execute control programs to operate final control elements. SCADA software then interfaces between field devices and control hardware for monitoring and operation.
This document provides an overview of key electrical concepts including:
- Voltage is the potential difference measured in volts that causes current to flow. Current is the rate of flow of electric charge measured in amperes.
- Ohm's law defines the relationship between voltage, current, and resistance in a circuit. Power is defined as voltage multiplied by current and describes the rate of energy transfer.
- Common circuit components are described including resistors, capacitors, diodes, transistors, integrated circuits, and how they are connected using printed circuit boards. Direction of electron and conventional currents are also discussed.
This document discusses the history and development of high voltage engineering. It begins with early experiments with static electricity by ancient Greeks. Key figures who contributed include Franklin, Faraday, Tesla, and Edison. Faraday's law established that a magnetic field can induce current in a wire. Advances allowed longer distance power transmission. Challenges included developing high voltage insulation. Numerical methods like finite element analysis are now used to model electric field distributions in complex high voltage components.
This presentation is brief history of Electrical Engineering. It lists and discuss about many scientists and their part in Electrical Engineering (Inventions). It also explains recent trends in Electrical Engineering.
A relay is an electrically operated switch that uses a small current to control a larger current. It was invented in 1835 and works by using an electromagnet to attract or repel a lever, opening or closing the switch contacts. Relays have two positions - normally open or normally closed - depending on the position of the contacts when the coil is not energized. They are commonly used to switch higher voltages or currents than simple solid-state switches can handle and can control multiple circuits at once.
3D integrated circuits stack active electronic components in multiple layers within a single circuit to reduce wasted space and improve interconnectivity between components. This allows both homogenous and heterogeneous chips to be accommodated. The substrate is divided into tiers with similar components stacked together to ease interconnections. Fabrication methods include beam recrystallization, processed wafer bonding, and solid phase crystallization. Routing in 3D considers multiple layers and placement of inter-wafer vias to reduce delays. MAGIC layout editing software provides bonding commands to treat layered designs as single entities. 3D ICs provide significant improvements over conventional 2D designs.
This document discusses the use of robots in power plants. It begins with introductions to artificial intelligence and its applications. There are three main types of power plants - thermal, hydroelectric, and nuclear. Robots can be used for mobile monitoring in thermal plants using sensors. One robot described is a "line scout" with a robotic arm that can inspect and perform maintenance on high-voltage transmission lines. Robots are also useful in nuclear plants for hazardous environments like areas with radiation. One robot highlighted is a "snake-arm" robot that can perform inspections and navigate confined spaces to reach areas that are difficult for humans, such as being used currently in nuclear plant maintenance and inspections.
now a days power requirement is increasing day by day.
to meet the requirements new power plants constructing, for maintenance of these plants skilled man power is not sufficient. in such cases a robot which can maintain the power system satisfies the requirements.
Electronics is the branch of science dealing with the controlled movement of electrons. Electronics has applications in communication, entertainment, industry, medical science, and defense. There are two main types of electronic components - active components and passive components. Active components like transistors and logic gates can amplify or process electrical signals, while passive components like resistors, capacitors, and inductors cannot amplify or process signals. Transistors act as switches to regulate current or voltage, and logic gates are basic building blocks of digital circuits. Resistors limit electrical current, capacitors store energy electrostatically, and inductors store energy magnetically.
Introduction to HMI (Human Machine Interface) | Just EngineeringJustengg1
Introduction to HMI is (Human Machine Interface) software designed for the interface between the user and the machine. HMI is a device that acts as an interface between the PLC and the operator. For More information visit : http://www.justengg.com or contact us: +91 7276030903 /+91 7756911229
The document discusses network interface cards (NICs) and hubs. It provides details on:
- What a NIC is and its purpose of connecting a computer to a network and allowing communication. NICs come in wired and wireless varieties.
- The need for NICs to accommodate differences in processing speeds between computers and networks. NICs handle transmission and reception without requiring constant CPU processing.
- What a hub is and its purpose of connecting multiple devices on a network. Hubs operate at the physical layer and repeat signals to all ports, creating a single collision and broadcast domain.
- The different types of hubs including passive hubs that simply pass signals, active hubs that
Power electronics & power electronic systemAkshay Parmar
Power electronics involves efficiently converting electrical energy from one form to another using semiconductor devices. It deals with modifying electrical energy on a power level rather than signal level. Power electronic converters can be found wherever electrical energy needs to be modified, ranging from milliwatts to hundreds of megawatts. Power conversion systems can be classified based on their input and output power types, such as AC to DC, DC to AC, DC to DC, and AC to AC conversion.
This document discusses power supplies and switched mode power supplies (SMPS). It begins with an overview of power supplies and their basic components like transformers, rectifiers, and regulators. It then covers the categories of power supplies, including linear regulated and SMPS. The document discusses the components and workings of SMPS in detail, including the inverter, output transformer, rectifier and filter. It covers the advantages of SMPS like higher efficiency and smaller size compared to traditional power supplies. In the end, it discusses different feedback techniques used in SMPS.
The complete list of thyristor family members include diac (bidirectional diode thyristor), triac (bidirectional triode thyristor), SCR (silicon controlled rectifier), Shockley diode, SCS (silicon controlled switch), SBS (silicon bilateral switch), SUS (silicon unilateral switch) also known as complementary SCR or CSCR, LASCR (light activated SCR), LAS (light activated switch) and LASCS (light activated SCS).
This document provides an overview of programmable logic controllers (PLCs). It defines a PLC as a digital computer used for industrial control systems. The document outlines the history of PLCs, their major components including the processor, power supply, and I/O modules. It describes the operational sequence of a PLC including input scan, logic solve, and output scan. Programming methods like ladder logic and functional block diagrams are discussed. Examples are provided of ladder logic programs for starting and stopping a motor. Advantages of PLCs include reliability, flexibility, and cost effectiveness. The document concludes by listing some common industrial applications of PLCs.
This document discusses power quality and defines it as the ability of a power system to supply voltage continuously within tolerances. It outlines various power quality events like sags, swells, interruptions, harmonics, and their causes and effects. It then describes various techniques to mitigate power quality issues, including dynamic voltage restorers, harmonic filters, static VAR compensators, and unified power quality conditioners. Maintaining high power quality improves system efficiency and equipment lifespan while eliminating problems like voltage fluctuations, harmonics, and reactive power issues.
This document discusses different types of sensors and their characteristics. It covers the differences between active and passive instruments, as well as null-type and deflection-type instruments. It also discusses analogue versus digital instruments and some key sensor performance characteristics such as accuracy, precision, threshold, resolution, sensitivity, linearity, hysteresis and more. Key factors that influence sensor selection are resolution requirements, cost, accuracy needs, and application environment. Proper sensor selection depends on balancing these factors for each unique measurement scenario.
An electric circuit is a closed loop that allows electric current to flow from a power source through various components like switches, fuses, and loads, and back to the source. The main parts of a circuit include an electrical source that delivers power, controlling devices that regulate the current, protection devices that prevent damage, conducting wires or paths, and loads that use the power. Circuits can be open or closed, and classified as series, parallel, or a combination depending on how the components are connected.
The presentation explain principal, working and construction and application of Potentiometer it is useful for senior secondary students of Indian school
ELECTRICAL AND ELECTRONICS MEASUREMENT Dinesh Sharma
This document discusses measurement techniques and instruments. It covers the basic components, classifications, functions, and errors of measurement instruments. The key points are:
- Measurement instruments have components for deflection, control, and damping of the pointer. Deflection indicates the measured quantity, control opposes deflection, and damping reduces oscillations.
- Instruments can be classified as analog or digital, absolute or secondary. Accuracy depends on design, materials, and errors like systematic, random, and environmental errors.
- Measurements involve comparing an unknown quantity to a standard and expressing the result numerically. Direct comparison is used when possible, otherwise indirect methods are used. Proper standards and methods are required for meaningful results.
This document appears to be an excerpt from a textbook on mathematical methods. It includes exercises and solutions involving various mathematical concepts like functions, derivatives, integrals, and equations. Specifically, it is from Chapter 9 and is exercise 9.7 spanning pages 1 through 3. The text includes mathematical expressions, equations, and workings out steps to solve problems.
The document appears to be an excerpt from a textbook on mathematical methods. It contains mathematical expressions and equations. Specifically, it discusses:
1) Functions of a variable and their derivatives, including notation for derivatives.
2) Rules for differentiation, such as the power rule and chain rule.
3) Taking the derivative of various functions, such as exponential, logarithmic, trigonometric and inverse trigonometric functions.
This document discusses the history and development of high voltage engineering. It begins with early experiments with static electricity by ancient Greeks. Key figures who contributed include Franklin, Faraday, Tesla, and Edison. Faraday's law established that a magnetic field can induce current in a wire. Advances allowed longer distance power transmission. Challenges included developing high voltage insulation. Numerical methods like finite element analysis are now used to model electric field distributions in complex high voltage components.
This presentation is brief history of Electrical Engineering. It lists and discuss about many scientists and their part in Electrical Engineering (Inventions). It also explains recent trends in Electrical Engineering.
A relay is an electrically operated switch that uses a small current to control a larger current. It was invented in 1835 and works by using an electromagnet to attract or repel a lever, opening or closing the switch contacts. Relays have two positions - normally open or normally closed - depending on the position of the contacts when the coil is not energized. They are commonly used to switch higher voltages or currents than simple solid-state switches can handle and can control multiple circuits at once.
3D integrated circuits stack active electronic components in multiple layers within a single circuit to reduce wasted space and improve interconnectivity between components. This allows both homogenous and heterogeneous chips to be accommodated. The substrate is divided into tiers with similar components stacked together to ease interconnections. Fabrication methods include beam recrystallization, processed wafer bonding, and solid phase crystallization. Routing in 3D considers multiple layers and placement of inter-wafer vias to reduce delays. MAGIC layout editing software provides bonding commands to treat layered designs as single entities. 3D ICs provide significant improvements over conventional 2D designs.
This document discusses the use of robots in power plants. It begins with introductions to artificial intelligence and its applications. There are three main types of power plants - thermal, hydroelectric, and nuclear. Robots can be used for mobile monitoring in thermal plants using sensors. One robot described is a "line scout" with a robotic arm that can inspect and perform maintenance on high-voltage transmission lines. Robots are also useful in nuclear plants for hazardous environments like areas with radiation. One robot highlighted is a "snake-arm" robot that can perform inspections and navigate confined spaces to reach areas that are difficult for humans, such as being used currently in nuclear plant maintenance and inspections.
now a days power requirement is increasing day by day.
to meet the requirements new power plants constructing, for maintenance of these plants skilled man power is not sufficient. in such cases a robot which can maintain the power system satisfies the requirements.
Electronics is the branch of science dealing with the controlled movement of electrons. Electronics has applications in communication, entertainment, industry, medical science, and defense. There are two main types of electronic components - active components and passive components. Active components like transistors and logic gates can amplify or process electrical signals, while passive components like resistors, capacitors, and inductors cannot amplify or process signals. Transistors act as switches to regulate current or voltage, and logic gates are basic building blocks of digital circuits. Resistors limit electrical current, capacitors store energy electrostatically, and inductors store energy magnetically.
Introduction to HMI (Human Machine Interface) | Just EngineeringJustengg1
Introduction to HMI is (Human Machine Interface) software designed for the interface between the user and the machine. HMI is a device that acts as an interface between the PLC and the operator. For More information visit : http://www.justengg.com or contact us: +91 7276030903 /+91 7756911229
The document discusses network interface cards (NICs) and hubs. It provides details on:
- What a NIC is and its purpose of connecting a computer to a network and allowing communication. NICs come in wired and wireless varieties.
- The need for NICs to accommodate differences in processing speeds between computers and networks. NICs handle transmission and reception without requiring constant CPU processing.
- What a hub is and its purpose of connecting multiple devices on a network. Hubs operate at the physical layer and repeat signals to all ports, creating a single collision and broadcast domain.
- The different types of hubs including passive hubs that simply pass signals, active hubs that
Power electronics & power electronic systemAkshay Parmar
Power electronics involves efficiently converting electrical energy from one form to another using semiconductor devices. It deals with modifying electrical energy on a power level rather than signal level. Power electronic converters can be found wherever electrical energy needs to be modified, ranging from milliwatts to hundreds of megawatts. Power conversion systems can be classified based on their input and output power types, such as AC to DC, DC to AC, DC to DC, and AC to AC conversion.
This document discusses power supplies and switched mode power supplies (SMPS). It begins with an overview of power supplies and their basic components like transformers, rectifiers, and regulators. It then covers the categories of power supplies, including linear regulated and SMPS. The document discusses the components and workings of SMPS in detail, including the inverter, output transformer, rectifier and filter. It covers the advantages of SMPS like higher efficiency and smaller size compared to traditional power supplies. In the end, it discusses different feedback techniques used in SMPS.
The complete list of thyristor family members include diac (bidirectional diode thyristor), triac (bidirectional triode thyristor), SCR (silicon controlled rectifier), Shockley diode, SCS (silicon controlled switch), SBS (silicon bilateral switch), SUS (silicon unilateral switch) also known as complementary SCR or CSCR, LASCR (light activated SCR), LAS (light activated switch) and LASCS (light activated SCS).
This document provides an overview of programmable logic controllers (PLCs). It defines a PLC as a digital computer used for industrial control systems. The document outlines the history of PLCs, their major components including the processor, power supply, and I/O modules. It describes the operational sequence of a PLC including input scan, logic solve, and output scan. Programming methods like ladder logic and functional block diagrams are discussed. Examples are provided of ladder logic programs for starting and stopping a motor. Advantages of PLCs include reliability, flexibility, and cost effectiveness. The document concludes by listing some common industrial applications of PLCs.
This document discusses power quality and defines it as the ability of a power system to supply voltage continuously within tolerances. It outlines various power quality events like sags, swells, interruptions, harmonics, and their causes and effects. It then describes various techniques to mitigate power quality issues, including dynamic voltage restorers, harmonic filters, static VAR compensators, and unified power quality conditioners. Maintaining high power quality improves system efficiency and equipment lifespan while eliminating problems like voltage fluctuations, harmonics, and reactive power issues.
This document discusses different types of sensors and their characteristics. It covers the differences between active and passive instruments, as well as null-type and deflection-type instruments. It also discusses analogue versus digital instruments and some key sensor performance characteristics such as accuracy, precision, threshold, resolution, sensitivity, linearity, hysteresis and more. Key factors that influence sensor selection are resolution requirements, cost, accuracy needs, and application environment. Proper sensor selection depends on balancing these factors for each unique measurement scenario.
An electric circuit is a closed loop that allows electric current to flow from a power source through various components like switches, fuses, and loads, and back to the source. The main parts of a circuit include an electrical source that delivers power, controlling devices that regulate the current, protection devices that prevent damage, conducting wires or paths, and loads that use the power. Circuits can be open or closed, and classified as series, parallel, or a combination depending on how the components are connected.
The presentation explain principal, working and construction and application of Potentiometer it is useful for senior secondary students of Indian school
ELECTRICAL AND ELECTRONICS MEASUREMENT Dinesh Sharma
This document discusses measurement techniques and instruments. It covers the basic components, classifications, functions, and errors of measurement instruments. The key points are:
- Measurement instruments have components for deflection, control, and damping of the pointer. Deflection indicates the measured quantity, control opposes deflection, and damping reduces oscillations.
- Instruments can be classified as analog or digital, absolute or secondary. Accuracy depends on design, materials, and errors like systematic, random, and environmental errors.
- Measurements involve comparing an unknown quantity to a standard and expressing the result numerically. Direct comparison is used when possible, otherwise indirect methods are used. Proper standards and methods are required for meaningful results.
This document appears to be an excerpt from a textbook on mathematical methods. It includes exercises and solutions involving various mathematical concepts like functions, derivatives, integrals, and equations. Specifically, it is from Chapter 9 and is exercise 9.7 spanning pages 1 through 3. The text includes mathematical expressions, equations, and workings out steps to solve problems.
The document appears to be an excerpt from a textbook on mathematical methods. It contains mathematical expressions and equations. Specifically, it discusses:
1) Functions of a variable and their derivatives, including notation for derivatives.
2) Rules for differentiation, such as the power rule and chain rule.
3) Taking the derivative of various functions, such as exponential, logarithmic, trigonometric and inverse trigonometric functions.
This document appears to be an exercise from Chapter 9 on mathematical methods from a textbook. It includes mathematical expressions and equations regarding functions, derivatives, and integrals. The goal of the exercise seems to be practicing taking derivatives and integrals of various functions, as well as using mathematical rules and properties to simplify expressions.
The document presents mathematical methods for solving differential equations. It introduces the concept of a differential equation and gives examples of basic differential equations like separable, linear, and exact equations. It then describes various methods for solving differential equations including:
- The method of separation of variables for separable differential equations
- The method of integration factors for exact differential equations
- The method of undetermined coefficients for non-homogeneous linear differential equations
The document provides solutions to various mathematical problems using techniques of differentiation and integration. Some of the problems involve finding derivatives of functions, evaluating definite integrals, and solving differential equations. The steps for solving each problem are shown using mathematical notation along with explanations of the techniques used.
The document is illegible and contains no discernible words or meaningful information. It appears to be random characters and symbols with no context or substance that could be summarized.
This document discusses an organization that was considered to be irresponsible and whose name should not be connected to a Bureau even though they were working together. As a result, the organization's name was not to be used. The document also references someone named John Laval and discusses the impact of the organization's actions.
This document is a response from the FBI to a correspondent regarding an organization called the Committee on Aerial Phenomena. The FBI has not investigated the organization and has received no complaints against them alleging violation of any laws under the FBI's jurisdiction. The FBI provided the correspondent with several pamphlets about combating communism, but the document contains no identifiable information referring to the correspondent.
This document is an intern performance evaluation survey for an intern named [Intern Name]. It asks the evaluating manager to rate the intern on various success factors like quality of work, leadership, excellence, business orientation, and interpersonal skills on a scale of 1 to 5, with 1 being "Does Not Meet Expectations" and 5 being "Exceptional Performance". It also asks the manager to provide an overall rating of the intern's general development throughout the internship. Additional questions ask if the manager would consider the intern for a future internship or full-time employment. The manager provides positive feedback about the intern's strong performance, work ethic, and potential for future opportunities.
The National Investigations Committee on Aerial Phenomena (NICAP) is forming to investigate UFO sightings and determine if "flying saucers" exist. The committee is led by Thomas Brown and plans to elect a board of governors. It will operate as a privately funded fact-finding group to serve the public interest. Membership levels range from $7.50 to $1,000 and the goal is to raise $2-3 million for research.
PowerPoint version of ACAD CD Demo originally published in Irfanview. Disregard onscreen navigation prompts. Prepared to demonstrate the capabilities of CAD in the Theatrical Construction environment - and to showcase my skills in 2D Drafting
1. The document provides calculations and solutions for derivatives of various orders.
2. Equations are derived for nth order derivatives of functions containing terms like (a-x) and (a+x).
3. The derivatives are expressed in terms of factorial terms involving n.
This document discusses implementing compressed air leak repairs at an industrial facility. It begins by providing background on the presenters and outlining common issues with compressed air systems, including leaks that can account for 25-55% of generation costs. The document then discusses how to perform a leak survey by gathering information about the system and layout. It presents different methods for calculating the financial opportunity of fixing leaks, including an old formula and a new spreadsheet approach. Finally, it discusses making air leaks visible using ultrasonic detection tools and pressure gauges to more accurately quantify leak volumes and savings.
A woman reported seeing an unidentified flying object on April 5, 1956 while driving near Henderson, North Carolina. She described the object as very bright and luminous, shaped like an egg and making no sound. She was unable to determine the exact size but estimated it was less than 25 feet away. The letter seeks John Edgar Hoover's input on whether any similar reports were made to the FBI regarding two men who supposedly came from Venus and met with a journalist in Los Angeles in March 1953.
This letter from J. Edgar Hoover, the director of the FBI, acknowledges receipt of a letter from a correspondent reporting a sighting of an unidentified flying object. The correspondent saw an object in the sky that changed shapes and appeared to trail something below it, leading them to think it may have been a flying disc. However, given the limited information provided and possibility it was just a weather balloon, no further investigation was deemed necessary.
this work took many years as this case was much suppressed by british-The sui...Agha A
- Lieutenant Colonel John Mawson was an officer in the 14th Light Dragoons who compiled records of General Sir Charles Napier's orders and remarks while commander of the British forces in India.
- These records discuss an incident where Colonel William Locke, commander of the 14th Light Dragoons, committed suicide at Meerut in 1849 on the eve of the Second Sikh War.
- The records also mention Major John Hall, another officer who originally served in the 14th Light Dragoons in 1824 during the First Anglo-Burmese War and was later killed during the actions along with 4 troops of the 14th Light Dragoons.
Satellite images bring the ability to capture a wide area in one go, and to acquire systematic, standardized and up-to-date information for both farmers and nature managers. However, cloud coverage often blocks satellite views of crop fields during crucial periods. Where satellite imagery lacks sufficient resolution, coverage, or timing, BIOSCOPE will use unmanned aerial systems to provide higher resolution imagery as a more sustainable alternative to airplanes. The goal is to create an on-demand satellite and UAS service to make imagery more reliable, robust and adaptable to user needs.
1) The document lists various measurements taken at different times.
2) Measurements include temperature, wind speed, and other weather variables.
3) Data is recorded on multiple dates over an unspecified time period.
Similar to Easy laser printer maintenance and repair (20)
Build the Next Generation of Apps with the Einstein 1 Platform.
Rejoignez Philippe Ozil pour une session de workshops qui vous guidera à travers les détails de la plateforme Einstein 1, l'importance des données pour la création d'applications d'intelligence artificielle et les différents outils et technologies que Salesforce propose pour vous apporter tous les bénéfices de l'IA.
Impartiality as per ISO /IEC 17025:2017 StandardMuhammadJazib15
This document provides basic guidelines for imparitallity requirement of ISO 17025. It defines in detial how it is met and wiudhwdih jdhsjdhwudjwkdbjwkdddddddddddkkkkkkkkkkkkkkkkkkkkkkkwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwioiiiiiiiiiiiii uwwwwwwwwwwwwwwwwhe wiqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq gbbbbbbbbbbbbb owdjjjjjjjjjjjjjjjjjjjj widhi owqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq uwdhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhwqiiiiiiiiiiiiiiiiiiiiiiiiiiiiw0pooooojjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj whhhhhhhhhhh wheeeeeeee wihieiiiiii wihe
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Sri Guru Hargobind Ji - Bandi Chor Guru.pdfBalvir Singh
Sri Guru Hargobind Ji (19 June 1595 - 3 March 1644) is revered as the Sixth Nanak.
• On 25 May 1606 Guru Arjan nominated his son Sri Hargobind Ji as his successor. Shortly
afterwards, Guru Arjan was arrested, tortured and killed by order of the Mogul Emperor
Jahangir.
• Guru Hargobind's succession ceremony took place on 24 June 1606. He was barely
eleven years old when he became 6th Guru.
• As ordered by Guru Arjan Dev Ji, he put on two swords, one indicated his spiritual
authority (PIRI) and the other, his temporal authority (MIRI). He thus for the first time
initiated military tradition in the Sikh faith to resist religious persecution, protect
people’s freedom and independence to practice religion by choice. He transformed
Sikhs to be Saints and Soldier.
• He had a long tenure as Guru, lasting 37 years, 9 months and 3 days
Blood finder application project report (1).pdfKamal Acharya
Blood Finder is an emergency time app where a user can search for the blood banks as
well as the registered blood donors around Mumbai. This application also provide an
opportunity for the user of this application to become a registered donor for this user have
to enroll for the donor request from the application itself. If the admin wish to make user
a registered donor, with some of the formalities with the organization it can be done.
Specialization of this application is that the user will not have to register on sign-in for
searching the blood banks and blood donors it can be just done by installing the
application to the mobile.
The purpose of making this application is to save the user’s time for searching blood of
needed blood group during the time of the emergency.
This is an android application developed in Java and XML with the connectivity of
SQLite database. This application will provide most of basic functionality required for an
emergency time application. All the details of Blood banks and Blood donors are stored
in the database i.e. SQLite.
This application allowed the user to get all the information regarding blood banks and
blood donors such as Name, Number, Address, Blood Group, rather than searching it on
the different websites and wasting the precious time. This application is effective and
user friendly.
This study Examines the Effectiveness of Talent Procurement through the Imple...DharmaBanothu
In the world with high technology and fast
forward mindset recruiters are walking/showing interest
towards E-Recruitment. Present most of the HRs of
many companies are choosing E-Recruitment as the best
choice for recruitment. E-Recruitment is being done
through many online platforms like Linkedin, Naukri,
Instagram , Facebook etc. Now with high technology E-
Recruitment has gone through next level by using
Artificial Intelligence too.
Key Words : Talent Management, Talent Acquisition , E-
Recruitment , Artificial Intelligence Introduction
Effectiveness of Talent Acquisition through E-
Recruitment in this topic we will discuss about 4important
and interlinked topics which are
3. Oscilloscope startup procedures 6]
Voltage measurements 62
Time and frequency measurements 64
Service guideiiries 65
The troubleshooting cycle 65
Define your symptoms 66
identify and isolate 66
Repair or replace 6'7
Re-test 68
Gathering technical data 68
Electricity hazards 69
Static electricity '71
Static formation 72
Device damage '72
Controlling static electricity '78
Reassembly and disassembly hints '74
Housing disassembly '74
Electromechanical disassembly '74
Reassembly '75
Eiectrepiiutograpiiie teeitnolcgy 7'7
The electrophotographic approach 78
Cleaning '79
Charging 80
Writing 8]
Developing 82
Transfer 88
Fusing 84
Writing mechanisms 84
Lasers 85
LEDs 88
LCSs 89
The electrophotographic cartridge 90
Protecting an EP cartridge 91
Power supplies 98
Power supplies—~ac and linear dc 94
Transformers 94
The ac power supplies 96
Rectifiers 96
Filters 98
Regulators 99
Troubleshooting ac and linear dc supplies 102
Construction and operation of dc switching supplies 107
4. Troubleshooting dc switching supplies 1 J 0
High~voltage supply troubleshooting 1 J4
irnagefliurntatiuri system tin
System start-up problems J 1 '7
Laser-delivery problems Z Z 9
Fusing-assembly problems Z22
image-formation problems 124
R/ieeiiariieai systerns rs?
Paper problems Z88
Sensor and interlock problems J46
Resistive sensors Z46
Mechanical sensors J4'7
Optical sensors J48
Troubleshooting sensors and interlocks J48
SC&l'll1@l‘-1I10llO1‘/11183111-I‘fiOtOI‘ problems J 50
EP cartridge problems J 51
Tire eleetrunie euntrui paeirage E54
Communication J 55 ‘
Printer communication background 1 56
ASCll explained J 56
Control codes Z 5'7
1lumber systems J 5'7
Binary digits J 58
Communication links 159
Communication standards Z 60
Parallel communication Z 60
Serial communication J 6.8
lsolating the communication interface J 64
Troubleshooting a parallel interface Z 64
Troubleshooting a serial interface J 6'7
Memory J 69
Permanent memory Z 69
Temporary memory J '70
Troubleshooting memory 1'7]
Control panel 1'71
Sealed switches 1'72
Troubleshooting a control panel 1'78
Main logic J 78
Microprocessor operations 1'74
The system clock 1'75
ASIC operations 1'75
Troubleshooting main logic 1 '76
5. APPENDTQES
A Typieai eieaning and inaintenanee E 78
R Qnnipreiiensiye trnublesiinuting guides E84
Q Vendors W2
Glcssary f%
index 268
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8. 2 T/ize c?[8C7Z7i"'Op/‘2.i»OZOQ'i"CZ.QU/'Z»’ZlC? _];)'?""’Z1"lr'ZiZi6")"
world. This book shows you how modern laser printers work and explains how to
maintai.ii them effectively.
..-art verview
The intense competition between printer manufacturers has resulted in a stag-
gering variety of laser priiiter models—each with different sizes, shapes, and fea-
tures. ln spite of this physical diversity, every laser printer ever made performs the
same set of functions to 'f.l.'&l.l.SCl‘l.DO the output of a computer into some permanent
paper form. The process seems simple enough, right‘? in reality, however, it requires
a complex interacti.on of electncal, electronic, and mechanical parts all working to-
ether to make a practical laser printer. Stop for moment and consider some things
rat a laser printer must be capable of.
First, the laser printer can do nothing at all without a host computer to provide
data and control signals, so a conununication link must be established. To operate
with any computer system, the printer must be compatible with one or more standard
communication interfaces that have been developed. A printer must be able to use a
wide variety of paper types and thicknesses, which can include such things as en-
velopes and labels. it must be capable of printing a vast selection of type styles and
sizes, well. as gifaphics images, then mix those images together onto the same page.
The laser printer miist be fast. lt must communicate, process, and print infor-
riiation as quickly as possible. Laser printers must also be easy to use. Many features
and options are accessible with a few careful strokes of the control panel. Paper in-
put and output must be convenient. Expendable supplies such as toner should be
quick and easy to chaiige. Fiiilitll}/', laser printers must be reliable. They must produce
even and C.OlIl.SlSlI€1ill print over a long working life»-often more than 300,000 pages
(expendable items must be iI‘€plEtC€C;l more ;l’requently).
as-e*i.e
i it- -{*1 . -» 1 -- ..- T
'3 Er _ M .5 _ V -_ it @
You are pi'obably woiidering why people use the term eLccti"ophotogmpitic
_']3"7"’Zl’7"Z.Zi€7"‘ when talking about laser printers. ln truth, electrophotographic (or EP) is a
broad l1€lf'll1 that refers to a 131‘.ilj1il€1I‘ that functions using the electrophotographic
proces Laser" printers are electrophotographic printers that use a laser beam to
write image data, but there are also LED (light-emitting diode) page printers that
use a bar of mici*oscopic LEDs, instead of a laser beam, to write image data. Both
laser and LED printers are electrophotographic printers (although laser-type print»
ers more conunon). You can learn much more about the electrophotographic
process and see how laser and LED printers work in this book. In this book, the
terms EP];>rr"2Irrz.te1", l(Tt88"'l"])7"Z-"12.-t€'?"‘, and LED ];>r/2'/utc/2" are interchangeable.
U3
nQ51? nRifleatnr seeifieatis
Make it point to know your laser printer specifications and features before you
begin any repair. The specifications and features give you a good idea what the
9. Fca.tw"es cmd specifications 3
printer can do, which might help you to test it more thoroughly during and after your
repair. A listing of specifications is usually contained in an introductory section of
the printer instruction manual or at the end in an appendix. If you do not have a copy
of the printer documentation on hand, the manufacturer can often fax a copy of the
specifications directly to you. Remember that there is no standard format for listing
printer specifications. The format is up to the preferences of each manufacturer. Re-
gardless of how the specifications are listed, you will most often find the following
subjects: power requirements, interface compatibility, print capacity, print charac-
teristics, reliability/life information, environmental information, and physical infor-
mation. Each of these specifications has some importance, so you should be familiar
with them in detail.
Puwer requirements
As with any electrical device, a printer requires power to function. Voltage, fre-
quency, and power consumption are the three typical specifications that you will find
here. Domestic U.S. voltage can vary from I05 to I30 Vac (alternating-current volts)
at a frequency of 60 Hz (hertz). European voltage can range from 210 to 240 Vac at
50 Hz. Many current laser printers have a power selection switch that toggles the
printer between 120 and 240 V operation. Power consumption is rated in watts (W).
Depending on the particular model, laser printers can use up to 900 W during print-
ing. However, most models use an automatic power-down mode that shuts down the
major power-consuming components after the printer is idle for several minutes.
Chapter 6 discusses the operation and repair of laser printer power supplies.
interface cninnatihiiity
A printer is a pc’r'2Ip/teral device. That is, it serves no purpose at all unless it can
communicate (or Z/nterfctce) with a computer. A communication link between
printer and computer can be established in many different ways, but three interface
techniques have become standard: RS-232, Centronics, and IEEE 488. Only a prop-
erly wired and terminated cable is needed to connect the printer and computer.
Printer communication and troubleshooting are discussed in chapter 9.
RS-282 is a serial interface used to pass binary digits (or bits) one at a time be-
tween the computer and printer. Serial links of this type are very common, not just
for printers, but for other serial communication applications such as modems and
simple digital networks. RS-232 is popular due to its high speed, physical simplicity,
and its ability to handle data over long distances.
Ceittrom'cs is the standard for parallel communication. Although one used ex-
clusively by printers, parallel communication has become popular for other peripher-
als such as parallel-port tape drives and portable CD-ROIVI (compact disc read-only
memory) drives. Centronics is a de facto standard, so it is not officially endorsed by
standards organizations such as the IEEE (Institute of Electrical and Electronic En-
gineers), EIA (Electronic Industries Association), or CCITT (International Consulta-
tive Committee for Telephone and Telegraph). Instead of passing one bit at a time,
Centronics interfaces pass entire characters from the computer to the printer as sets
of bits. Centronics is popular because of its functional simplicity. Although parallel
10. 4 The electrop/totog?/up/1'20 ]J7”Z7’?/Z6’?
connections require more interconnecting signal wires than an RS-232 cable, the
hardware required to handle parallel information is simpler.
[EEE 488, also known as GPIB (general-purpose interface bus), is an official
IEEE standard for parallel communication. It is not as widely used as Centronics or
RS-2-32, but GPIB supports network and bidirectional communication between in-
struments. The GPIB technique Was originally developed by Hewlett-Packard Goin-
pany, where it is still widely used in their line of printers and plotters.
Print capacity
Pi'"mt co;-pdc/tip is a generic term including several different laser printer specifi-
cations that outline what a printer can do. One of the most common print capacity
specifications is p7"’Z’7”?,l§ speed, which is measured in pages per minute (ppm). Inex-
pensive EP printers work at 4 ppm, but 8 to 10 ppm printers are available. Next, you
must be concerned with '1/'esoZ.ut'io"r"2., which is the number of individual dots that can
be placed per linear inch. Typical EP printers offer 300 >< 300 dpi (dots per inch) res-
olution (300 lines per inch at 300 dots per linear inch, or 90,000 dots per square inch).
A resolution this high is adequate for most business and personal graphics. The cur-
rent generation of laser and LED printers is capable of 600 >< 600 dpi resolution.
You might find a section on paper specrfijcdtions. Although dot matrix and ink
jet printers are very flexible in accepting a wide variety of paper thicknesses and fin-
ishes, the paper used in laser printers must fall within certain weights and finishes if
the EP process is to work correctly. In most cases, standard letter-size, Xerography-
grade paper (16-24 pound bond) will work. The paper also should have a plain fin-
ish. Shiny or gloss-finished papers will cause problems with the EP process. Most
laser printers will handle envelopes, transparencies, and labels. Before choosing
such materials, be certain that they are labeled as safe or tested with laser printers.
Poor-quality materials can jam and damage your printer.
Me’n'zio'r*p is another important specification for EP printers. Because laser print-
ers assemble images as full pages of individual bits, the more memory that is avail-
able, the larger and more complex an image can be printed. Typical laser printers
offer 512 K (kilobytes) to 1 l/lb (megabytes), but 2-8 Mb is required for full-page
graphic images that might be produced with software such as CorelDraw. l/lost laser
printers offer memory upgrade options.
Print ciiaracreristics
Print characteristics specify just how printer images will appear, how they will
be produced, or how characters from the printer will be interpreted. Fonts, software
emulation, and character sets are the three specifications that you should be most
familiar with.
Ajbrit is a style of type with certain visual characteristics that distinguish it from
other type styles. These characteristics might include differences in basic character
formation, accents, and decorative additions (that is, Courier versus Helvetica type).
Figure l-.2 is an example of several basic printer fonts. Early laser printers relied on
font cartridges that contained ROl/is (read-only memories) that held the image data
for each font. To change a font, you changed the cartridge. However, with the rise of
Microsoft Windows and improved memory systems, most current laser printers use
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soft fonts, where the data for desired fonts is downloaded to the printer during the
actual printing process. Soft fonts also allow easy enhancements such as underlin-
ing, bold, italic, superscript, subscript, and so on.
All printers use their own built-in software “language” that is in the printer per-
manent memory. The language specifies such things as font formation (dot place-
ment) and size, h.ow to i'ecognize and respond to control codes or control panel
input, and more. This software language also tells the printer how to operate, coin-
nninicate, and respond to problems.
l/lost of these languages were originally developed by leading printer manufac-
turers such as Hewlett-Packard, IBM, and Epson. Other manufacturers that wish to
make their printers functionally compatible must use a software language that enm-
ldtes one or more of the existiiig language standai'ds. For example, most laser print-
ers will emulate the operatioir of a Hewlett-Packard Lasenlet lll. E~niitldt?lo'2r. in this
use means that even though a laser printer is physically and electronically different
from a LaserJet lll, it will respond as if it were Lasenlet lll when connected to a
host computer. Another typical printer language is Postscript.
Ordinarily when a character code is sent to a printer, it is processed and printed
as a fully formed alphanumeric character or other special symbol. However, because
a character code is not large enough to carry every possible type of text or special
symbol (for example, foreign-language characters or block graphics), characters are
grouped into Cf/ZCZ/)"CtCf€i" sets that the printer can switch between. Switching a char-
acter set is often accomplished through a series of computer codes or control panel
commands. A standard character set consists of 96 ASCII (American Standard Oode
for information Interchange) ch.aracters. The 96 characters include 26 uppercase
letters, 26 lowercase letters, l0 digits, punctuation, symbols, and some control
codes. Other character s can include 96 italic ASOll characters, international
characters (German, French, Spanish, etc.), and unique block graphics.
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Reiiability/iife inierniarien
Reliability and life ea¢pectcmc;y information expresses the expected working life
of the laser printer or its components in pages or time. For example, a typical EP
12. 0 1'/re etecwop/ziotog/mp/tic pm/rite*i"
toner cartridge is rated for 200»-250 pages, and the image-formation “engine” is rated
for up to 300,000 pages. Many printers are rated at 5,000 pages per month (about
200 pages per workday). You might see this same information expressed as MTBF
(mean time between failures).
Envirenrnentai inferinatien
Environmental specifications indicate the physical operating ranges of your
printer. Stomge Z€’l%]3€7"CLf2L’l/'8 and opercutmg rempemtitre are the two most
common environmental conditions. A typical laser printer can be stored in tern-
peratures between -10 and 50°C, but can only be used from 10 to 82°C (on aver-
age). It is a good idea to let your printer stabilize at the ambient temperature and
humidity for several hours before operating it. Reldtipe /in/n/2.vjd'1lty can often be al-
lowed to range from 10 to 90% during storage, but must be limited to a range of
40 to 70% during operation. Keep in mind that humidity limits are given as non-
condensing values. NO7ZCO'7Z-(.i€’l”L5i’)'Z-Q means that you cannot allow water vapor to
condense into liquid form. Liquid water in the laser printer would certainly dam-
age its image-formation system.
Your printer also might specify physical shoclr or mLb'2"dttoi"2, limits to indicate
the amount of abuse the printer can sustain before damage can occur. Shock or vi-
bration is usually rated in units of Q-force. Keep in mind that laser printers are re-
markably delicate devices; any substantial shock or vibration might disturb the
optics that direct the laser beam. LED printers are a bit more rugged, but also use
optics that can be damaged or misaligned by rough handling.
Pliysicai inforinatien
Physical information about a printer includes such routine data as the printer
height, width, depth, and weight. ln some cases, an operating noise level specifica-
tion is included to indicate just how loud the printer will be during operation and
standby. Noise specifications are usually given in dBA (A-weighted decibels).
icalasseies
No matter how diverse or unique EP printers might appear from one model to
another, their differences are primarily cosmetic. lt is true that each printer might
use different individual components, but every laser printer must perform a very
similar set of actions. As a result, most laser printers can be broken down into a se-
ries of typical sections, or functional areas as shown in Fig. 1-3. Before you trou-
bleshoot a printer, you must understand the purpose of each area.
The ac pewer suppiy
An ac power supply is usually a simple electronic module that provides en-
ergy for the fusing assembly heaters and erase lamp assembly. There is typically
little that goes wrong with the ac supply unless a serious fault in the fuser or erase
assemblies damages the supply. You can learn about power supply operation and
repair in chapter 6.
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i--3 Diagram of a typical laser printer.
The dc power supply
The dc (direct current) power supply converts main ac entering the printer into
one or more levels of dc that are used to power the printer electronics and electro-
mechanical devices (such as motors and clutches). Like the ac supply, a dc power
supply is a fairly rugged and reliable device unless a fault in some part of the printer
circuitry damages the supply. A cover interlock in the dc supply shuts down printer
operation if a protective cover is opened. You can learn about power supply opera-
tion and repair in chapter 6.
l-ligh-wvolrage power supply
The EP process relies on high-voltage (1,000 V or more) that is used to create
and dissipate the powerful static charges that move toner Within an EP printer. Even
though specialized components are used in high-voltage supplies, high voltages
place a great deal of stress on electronic parts, so high~voltage supplies tend to fail
more commonly than ordinary ac or dc supply modules. See chapter 6 for more in-
formation on power supplies.
Easing asseruhiy
images are developed on paper using a fine powder called toner. The toner must
be fixed to the paper (otherwise, the toner would smudge or simply blow off the
page). Heat and pressure are used to fuse toner to the paper. The fusing assembly
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uses a set of two rollers in compression, where the top roller is heated to melt the
toner. A paper‘ exit sensor detects the passage of paper through the printer, and the
thermistor sensor is used to regulate temperature in the heated fusing roller. Chap-
ters £5 and '7 present more detailed information about the fusing assembly.
Erase lamp assembly
The image that appears on a printed page has been transferred there as a latent
image written to a special photosensitive drum. Each time the drum rotates, the la-
tent image must be erased before a new image is written. The erase lamps clear the
drum thoroughly and allow the photosensitive surface to accept a new image. Erase
lamp failure is usually easy to spot as you can see in chapter 7.
lllain motor
EP printers rely on substantial mechanical activity. Paper must be drawn from a
supply tray, fed to the image formation system, fixed, then fed to the output tray. The
mechanical force needed to support all of these activities is provided by a single mo-
tor and mechanical drive assembly. Chapter 8 describes mechanical systems in detail.
Writing rneebariism
The data that makes up an image must be transferred (or “written”) to the pho-
tosensitive drum. As you can see in chapter 5, this transfer is achieved by directing
light across the drum surface. For a laser printer, writing is accomplished by scans
ning a laser beam across a drum. For an LED printer, the light generated by individ-
ual microscopic LEDs (one LED for every dot) transfers image data to the drum.
Writing is controlled by the main logic assembly (or ECP).
Scanner»-inotor assembly
When a laser is used as a writing mechanism, the beam must be scanned back
and forth across the drum surface. This scanning process uses a hexagonal mirror
that is rotated with a motor. Note that scanners are not needed for LED printers be~
cause there is no beam to scan across the drum. You can find more information on
scanner assemblies in chapter 8.
Papeneontrol assembly
Paper must be grabbed from the paper tray, registered with the latent image,
passed through the image foi‘niationl§ybten1, fused, and passed out of the printer. Al-
though the main motor turns constantly, not all portions of the paper handling sys-
tem can be in motion at all times. The paper control assembly provides the sensors
that detect the presence of paper in the paper tray, the presence of paper in the
manual feed slot, and the sensitivity of each EP cartridge for optimum printing. in
addition to sensors, the papencontrol assembly provides the paper pickup and reg»
istration roller clutches that grab and register the page during printing. Chapter 8
discusses the paper-handling assembly in detail.
15. Typ/Zeal assemblies 9
Main logic assembly
The main logic assembly (or electronic control package—-ECP) is the heart and
soul of your EP printer. The main logic assembly has most of the circuitry that oper-
ates the printer, including electronics that communicates with the computer and
control panel. l/lain logic is also responsible for checking and responding to input
provided by a variety of sensors. Problems that occur in main logic can range from
subtle problems to major malfunctions. Chapter 9 covers the main logic circuits
found in EP printers.
EP cartridge assembly
The Electrophotographic (EP) cartridge of a printer is a remarkable piece of en-
gineering that combines the toner supply and much of the printer image-formation
system into a single, replaceable cartridge. By replacing the EP cartridge, you also
replace delicate, wear-prone parts such as the primary corona, EP drum, and devel-
oper roller. The modularity of the cartridge simplifies the maintenance of your
printer and improves its overall reliability. The image-formation system is discussed
in chapter '7.
Qontrol-panel assembly
Users must be able to interface with the printer to select various options or op-
erating modes. llot only do current control panels provide multifunction buttons,
but most also provide an LCD display for printer status and menu prompts. The con-
trol panel is covered with main logic in chapter 9.
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To troubleshoot any electromechanical system, you must be familiar with the indi-
vidual electronic and mechanical components that you find inside. This chapter in-
troduces you to a cross-section of components found in most typical laser printers.
Your troubleshooting efforts are simplified if you can identify important components
on sight, understand their purpose, and spot any obvious defects. Keep in mind that
this chapter is by no means a complete review of every possible type of component,
but it will give you a good idea of what to expect.
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For the purpose of this discussion, mechanical parts basically serve a single pur-
pose--to transfer force from one point to another. For example, a laser printer uses
a single motor to operate the printer paper transport and image-formation systems.
The physical force of a motor must be transferred to the paper, as well as to the var-
ious rollers and mechanisms that make the printer work. This transfer is accom-
plished through a series of gears, pulleys, rollers, and belts. Whenever mechanical
parts are in contact with one another, they produce friction that causes wear. Lubri-
cants, bushings, and bearings work to minimize the damaging effects of friction.
Chapter 8 presents troubleshooting procedures for mechanical systems.
Qears
Gears perform several important tasks. Their most common application is to
transfer mechanical force from one rotating shaft to another. The simplest arrange-
ment uses two gears in tandem as in Fig. 2-1. When two gears are used, the direction
of secoi'ic£cz.ry rotation is opposite that of-the p'rimcm"y shaft. If secondary direction
must be the same, a third gear can be added as shown in Fig. 2-2. The orientation of
applied force can be changed by using angled (or beoeled) gears shown in Fig. 2-8.
By varying the angles of both gears, force,,can be directed almost anywhere. Several
secondary gears can be run from a single drive gear to distribute force to multiple lo-
cations simultaneously, which is a critical feature for laser printer operation.
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Not only can gears transfer force, they also can alter speed and amount of force
that is applied at the secondary shaft. Figure 2-4 shows the effects of simple gear ra-
tios. Gecrr ?"CtlL~’ZO8 are usually expressed as the ratio of the size of the primary gear to
that of the secondary gear (or of the number of gear teeth on the primary to that of
the secondary). For a Zirigli ratio, the primary gear is larger than the secondary gear.
As a result, the secondary gear will turn faster, but with less force. (For mechanical
parts that rotate, the force in the rotating parts is known as torqrue). The effect is
just the opposite for a low ratio. A small primary gear will turn a larger secondary
slower, but with more force. Finally, an equal ratio causes a primary and secondary
gear to turn at the same speed and force.
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Fuiieys
Pulley assemblies are common in many laser printers. Like gears, they are used
to transfer force from one point to another. Instead of direct contact, however, pul-
leys are joined by a CIZ'7""Z'/U6 Z/miactge, which is usually a belt, wire, or chain. The action
is much the same as the fan belt in your automobile or the drive chain on your bicy-
cle. A basic pulley set is shown in Fig. 2-5. A motor turns a drive pulley that is con-
Drive pulley
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2-5 Top view of a basic pulley set.
19. M8CflCZ7’?/ZCCLZ pciits 13
nected to a secondary pulley through a drive belt that is under tension. As the drive
pulley turns, force is transferred to the secondary through the linkage, so the sec-
ondary pulley also turns. Notice that both pulleys turn in the same direction. A pul-
ley/belt configuration is sometimes used as a conveyor belt to carry paper evenly to
the fusing rollers.
Pulleys and drive linkages will vary depending on their particular application.
Low-force applications can use narrow pulleys (little more than a wheel with a
groove in it) connected with a wire linkage. Wire is not very rugged, and its contact
surface area with both pulleys is small. Therefore, wire can slide when it stretches
under tension or if load becomes excessive. Belts and their pulleys are wider, so
there is much more surface contact around each pulley. Belts are usually stronger
than wire, so there is less tendency to stretch under tension. Greater strength makes
belt-driven pulleys better suited for heavier loads.
You can replace pulleys with sprocket wheels and a chain linkage. Because each
chain link meshes with the sprocket wheels, any chance of slipping is eliminated.
Chains are almost immune to stretching under tension, so chain drives are used to
handle the highest loads.
Boilers
Rollers are really a focal point of laser printer operation. Rollers not only serve
to grab a sheet of paper from the paper tray, but rollers position (or register) the pa-
per before printing. The image formation system uses several rollers to distribute
toner and transfer the image to paper. By passing the paper through a set of heated
rollers, the transferred image is fused to paper. Damaged, old, or dirty rollers might
have an adverse effect not only on paper handling, but on overall image quality.
Reducing fricrion
As with all mechanical systems, parts that are in contact with one another will
wear while the system operates due to unavoidable friction that occurs between parts.
Therefore, reducing friction will extend the working life of your printer. Lubrication,
bushings, and bearings are three commonly accepted methods of reducing friction.
Use of oils or grease is one way to reduce friction (and might prove effective in
small doses), but this Zabr'"iccttvLo'iv. must be replaced regularly for it to remain effec-
tive. Otherwise, it can wear away, dry out, or harden into thick sludge. Lubricants
also are notorious for collecting dust and debris from the environment, which even-
tually defeats any benefits that the lubricant can provide.
BU-S/’Z/Z71-Q8 are usually “throw-away” wear surfaces as shown in Fig. 2-6. A bush-
ing is made of softer materials than the parts it is separating, so any friction gener-
ated by moving parts will wear out the bushing before the other parts touch each
other. When a bushing wears out, simply replace it with a new one. Bushings are
much less expensive and easier to replace than major mechanical parts such as
slides or frames. Today, bushing materials are reliable, and can last throughout the
working life of the printer.
Probably the most effective devices for reducing friction between parts are
bearings. Bearings consist of a hard metal case with steel balls or rollers packed in-
side as shown in Fig. 2-7. Because each steel ball contacts a load-bearing surface at
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only one point, friction (and Wear) is substantially lower than for bushings. Unfortu-
nately, bearing assemblies are often much more expensive than bushings, so bear-
ings are used only to handle heavy loads, or in places that Would be too difficult to
change bushings. Most laser printers avoid the expense of bearings in favor of inex-
pensive bushings.
lectrecaicalcets
Electromechcm"iccil co'mpo’2'tents are a particular class of devices that convert
electrical energy into mechanical force or rotation. Relays, solenoids, and motors are
three common electromechanical components that you should understand. Each of
these important devices relies on the principles of electromagnetism.
Electromagnetisrn
Whenever electrical current passes through a conductor, a magnetic field is gen-
erated around the circumference of that conductor as shown in Fig. 2-8. Such a mag-
netic field can exert a physical force O11p67"’l’l’L8CLbl8 materials (any materials that can
be magnetized). The strength of a magnetic field around a conductor is proportional
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to the amount of current flowing through it. Higher amounts of current result in
stronger magnetic fields, and vice versa.
Unfortunately, it is virtually impossible to pass enough currentthrough atypical
wire to produce a magnetic field that is strong enough to do any useful work. The
magnetic field must somehow be concenitiated, usually by cro'tlrmg the wire as shown
in Fig. 2-9. When arranged in this way, the coil takes on magnetic poles just like a
permanent magnet. Notice how the direction of magnetic itlux always points to the
‘rt-O'7‘tlt pole of the coil. if the direction of current flow were reversed, the magnetic
poles of the coil also would be reversed.
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To concentrate magnetic forces even furtheif, a permeable core material can be
inserted into the coil center as in Fig. 2-10. Ty_3ica.lfly, iron, steel., and cobalt are con-
sidered the classical core materials, but iron-ceranuc blends are used as well. Coils
of wire such as these form the foundation of all electromechanical cleviceU2
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Reiays
A relay is simply a mechanical switch that is actuated with the electromagnetic
force generated by an energized coil. A diagram of typical relay is shown in Fig.
2-ll. The switch (or coittctct set) can be normally open (NO) or normally closed
(NC) while the coil is de~energi:z.ed. When activated, the magnetic field of the coil
causes normally open contacts to close, or normally closed contacts to open. Con-
22. l@* C';§' T;y,p'tcrz.l conrtpo~iz.ei2.ts
Contacts
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_ . _ __ A schematic view of relay
*~ Co1.l *- 1- . -configurations.
Normally Normally
Open (NC) Closed (NC)
tacts are held in their actuated positions as long as the coil is energized. lf the coil is
turned off, contacts will return to their normally open or closed states. Keep in mind
that a coil might drive more than one set of contacts.
Relays are not always easy to recognize on sight. l/lost relays used in electronic
circuits are housed in small rectangular containers of metal or plastic. Low-power re-
lays are available in oversized lC (integrated circuit) style packages and soldered
right into a PC (printed circuit) board just like any other integrated circuit. Unless
the relay internal diagram is printed on its outer case, you will need a printer
schematic or mamifacturer’s data for the relay to determine the proper input and
output functions of each relay pin.
Ruienuiris
SOZ-8"l‘2.-O'Z(Tt-S convert electromagnetic force directly into motion as shown in Fig.
2-l2. Unlike ordinary electromagnets whose cores remain fixed within a coil, a sole-
noid core is allowed to float back and forth without restriction. When energized, the
magnetic field generated by a coil exerts a force on its core (called a ptim.ge"r')that
pushes it out f'i'om its rest position.
Coil body
T Return Plunger
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lf left unrestrained, a plunger would simply shoot out if its coil and fall away.
Flungers usually retained by a spring or some other sort of mechanical return as-
sembly. Being retained, a plunger extends only to some known distance when the
coil is fired; then it automatically returns to its rest position when the coil is off.
Solenoids are commonly used as clutches in laser printer paper-handling systems.
Remember that the motor providing mechanical torque in the printer is constantly
running while a. page is being printed. However, the paper-grab and registration rollers
need only turn briefly during the printing cycle. Solenoid “clutches” are used to en-
gage and disengage the motor torque as needed.
23. Electrom.ec/trim/tcctl componems i7
Meters
./l/[otors are an essential part of every laser printer manufactured today. Motors
operate the entire mechanical transport system. Chapter 8 presents a detailed dis-
cussion of mechanical systems and service. For now, concentrate on the motor itself.
All motors convert electrical energy into rotating mechanical force (torque). ln
turn, that force can be distributed with mechanical parts to turn a roller or move a
belt. An "t"7’tCZ"L(.iCZ’Z-O71 motor provides torque through a series of powerful electromag-
nets (coils) around a permanent magnet core as shown in Fig. 2-13. The core
(known as a rotor) is little more than a shaft that is free to rotate as its poles en-
counter electromagnetic forces. Each coil (also called a phase or p/tctse 2.u“mct2Trtg) is
built into the motor stationary frame (or stcttor).
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2»-i3 Simplified view of a typical induction motor.
By powering each phase in its proper order, the rotor can be made to turn with
some amount of force. The amount of angular force generated by a motor is known
as torque. lnduction motors generally require two ac signals separated by a 90 de-
gree phase difference. These sinusoidal driving signals vary the strength of each
phase evenly to create smooth rotation. lnduction motors are rarely used in today’s
commercial printers because they do not lend themselves to the precise positioning
requirements of most printers. lnstead, a close cousin of the induction motor is used,
and the motor is called a ctc servo motor.
The dc servos are powered by bipolar dc signals rather than by sinusoidal ac.
Like the induction motor, a dc servo is turned by bipolar driver signals in rapid suc-
cession. Although dc servos are not very precise for positioning, they can hold a con-
stant speed very accurately. This characteristic makes dc servos ideal for driving the
scanner mirrors in laser printers that must rotate at a precise rate.
A popular variation of the dc servo motor is called a SZ§€].’)j_lJ’Z7’tQ motor. Physically,
a stepping motor (or stepper) is very similar to a dc servo, but the rotor/stator
arrangement is much more intricate. Like dc servos, stepper motors are driven by a
series of square wave pulses separated by a phase difference. The sudden shift in
drive signals coupled with the intricate mechanical arrangement causes the rotor to
jump (or step) in certain angular increments, not a smooth, continuous rotation.
Once the rotor has reached its next step, it will hold its position as long as driver sig-
24. i% Typiccil covrzpo'rze'mis
nals maintain their conditions. If driver? signals hold steady, the motor could remain
stationary indelimitely. A typical stepping motor can achieve 1.8 degrees per step,
which means a motor must make 200 (360 degrees divided by 1.8 degrees) individ-
ual steps to complete a single rotation. lilovvever, gear ratios can break down motor
movement into much finer divisions.
Stepping motors are ideal for precise positioning. Because the motor moves in
knovvn angular steps, it can be rotated to any position simply by applying the appro-
priate series of driver pulses. For example, suppose your motor had to rotate 180 de-
grees. ll’ each step equals l.8 degrees, you need only send a series ol’ lOO (180
degrees divided by 1.8 degrees) pulses to turn the rotor exactly that amount. Logic
circuits in the printer generate each pulse, then driver circuits amplify those pulses
into the high-power signals that actually operate the motor. Chapter 9 explains the
operation and repair of printer electronics.
h=_ _:,4-' - , ~,_ ._, ‘ »_‘ _, . ,‘»¢3,‘ . -V.
it .>.§;~_-.< =->. .~ ll is tr it 5::as-., it w ‘ii e 15='_ g; .4‘ rt,
li you intend to do any subassembly or component-level troubleshooting of laser
printer systems, you must have an unde1;'stan<;ling of the various electronic components
that are available. l/lost circuits contain both a.c:t"Z’ve and ,pcr».s.s/we components working
together. Passive components include resistors, capacitors, and inductors. They are
called pcissiue because their only purpose is to store or dissipate circuit energy.
Active components make up broader group of semiconductor-based parts such
as diodes, transistors, and all types of integrated circuits. They are referred to as ac-
tive because each component uses circuit energy to perform a specific set of func-
tions—they all do something. A component might be as simple as a recti.i’ier or as
complex as a microprocessor, but active parts are the key elements in modern elec-
tronic circuits. This part of the chapter shows you each general type of component,
how they Work, hovv to read their markiiigs, and how they fail.
Resistors
All resistors ever made serve a single purpose--to dissipate povver in a con-
trolled fashion. Resistors appear in most circuits, but they are usually used for such
things as voltage division, current limiting, etc. Resistoiis dissipate power by pre-
senting a resistance to the flovv of current. Wasted energy is then shed by the resis-
tor as heat. ln printer logic circuits, so little energy is Wasted by resistors that
virtually no temperature increase is detectable. ln high-energy circuits such as
power supplies, resistors can shed substantial amounts of heat. The basic unit of re-
sistance is the ohm. The symbol for resistance is the Greek symbol omega (Q). You
will see resistance also presented as kilohins (lrtl or thousands of ohms) or megohms
(Mil or nullions of ohms).
CCL7*"bO'7'L—f’ll7?'Z resistors, as shown in Fig. 2-14, have largely replaced carbon-com-
position resistors in most circuits requiring through-hole resistors. instead of carbon
filling, a very precise layer of carbon film is applied to a thin ceramic tube. The thick-
ness of this coating al’l’ects the amount ol’ resistance--thicker coatings yield lovver
levels of resistance, and vice versa. l/letal leads are attached by caps at both ends,
25. 1 i-ooo1,~c=n: L/L)!/L1./U‘Ibt7'l(/bib 17
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A swij‘crce-'n2..oin/2r2._t resistor is shown in Fig. 2-15. As with carbon-film resistors,
surface-mount resistors are formed by depositing a layer of carbon film onto a thin
ceramic substrate. Metal tabs are attached at both ends of the Wafer. Surface-mount
resistors a.re soldered directly on the top or bottom sides of a printed circuit board
instead of using leads to penetijate the PC board. Surface-mount resistors are in-
credibly small devices (only a few square millimeters in area), yet they offer very
tight tolerances. Surfa.ce-mount resistors are used extensively in computers and
printers.
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