The problem can come from many sources, like heat, power surges, and old age. Conducting smps troubleshooting is excruciatingly difficult, youre better off becoming a rocket scientist. Smps repair guide switch mode power supply repairing tips. In this article scott dorsey tells us how to repair switching mode power supplies.
A switchedmode power supply switchingmode power supply, switchmode power supply, switched power supply, smps, or switcher is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Thus, if it is operating a circuit and the ac power fails, the power supply will again start supplying power when the ac power comes back on. Troubleshooting switching power converters a handson guide. Fusetp1 tp3 tp4 tp5 tp6 tp8 tp7 dc voltage output tp9. Sep 16, 2018 troubleshooting switching power supply. How to repair a switchmodepowersupply smps homemade.
Bench evaluation of semiconductor ics used in power conversion describing standard and unusual techniques mastered by the author, while testing similar chips at national semiconductor. Troubleshooting a power supply circuit troubleshooting is the application of logical thinking combined with a thorough knowledge of circuit or system operation to identify and correct a malfunction. Switching power supply technical manual adm instrument. Troubleshooting a switching power supply part 2 february 27, 2015 march 11, 2015 admin in troubleshooting a switching power supply part 1, we had replaced u1 and cr12 based on the analog signatures from the huntron tracker showing them as bad. Learn to troubleshoot power supply problems techrepublic. This is why experienced pc technicians often look first at the psu when diagnosing pc hardware issues. Mode power supply reference manual should prove useful. A technician is troubleshooting a power supply circuit that outputs substantially less dc voltage than it should. Paula the astron sl series of power supplies are a low profile linear power supply not a switch mode design.
It highlights the fact that practice and theory are two sides of the same coinone of the first things one requires to be aware of while troubleshooting switching converters is that one must develop an ability to look at a practical problem through the eyes of supporting theory, and vice versa. This is especially useful for switching power supply circuits, where transistors are used to switch power on and off very rapidly in the voltage transformation and regulation process. Here i would like to share another article with you that talks about how i have solved a slightly. Secrets of smps repair and troubleshooting switch mode power supply smps repair sometimes can be easy and sometimes are quite difficult to solve the problem. To make the best choice of a solution, it is essential for designers to be familiar with the merits, drawbacks and design concerns of each approach. Do not expose the power supply to sun, high humidity, or dusty environments. Mosfet failure modes in the zerovoltageswitched full. Troubleshooting and repairing switch mode power supplies can be extremely confusing thing unless you have some one that will help you through the whole process. One is the main 5vdc output that powers the computer system.
About a year ago, i felt like going bonkers because i couldnt find the right instructional guide for troubleshooting switching power supply. Power supplies are sometimes equipped with emirfi filters on their inputs, to prevent highfrequency noise voltage created within the power supply circuit from getting back to the power source where it might interfere with other powered equipment. A systematic approach to troubleshooting consists of three steps. Troubleshooting switching power converters sciencedirect. May 23, 2018 in this article scott dorsey tells us how to repair switching mode power supplies. Power supply troubleshooting and repair tips youtube. Also using a square wave to drive the switching transistors switched mode operation ensures that they dissipate much less power than a conventional series regulator transistor. Troubleshooting list for powersupply startup issues step issue symptom solution prior to hooking up any cables, visual inspection. This allows a switching power supply to enjoy a much smaller form factor than linear regulators. Apr 24, 2001 troubleshooting pc power supplies by rodrigo zamora in data centers on april 24, 2001, 12. Whether you are an experienced power supply designer, designing your first switching power supply or responsible for a make or buy decision for power supplies, the variety of information in the switch. Again this means that, for a given amount of power output, smaller and cheaper transistors can be used, than in similarly rated linear power supplies. As switching supplies become ubiquitous in electronic devices today, it becomes that much more important to understand how they work and just as importantly how they fail.
The output voltage rating of a power supply operating in the constant current mode analogous to the output current rating of a supply operating in the constant voltage mode. This manual includes basic information for switching power supply, general. Whether you are a novice engineer or an industry veteran, you know that sinking feeling. View and download radio shack dc power supply owners manual online. Troubleshooting switch mode power supplies on giangrandi. A nice feature for unattended operation is that the power supply can be set to have its output on at the last poweron settings. Switch mode power supply measurements application note. Learn to troubleshoot power supply problems by marsha glick in data centers on july 19, 2001, 12.
About a year ago, i felt like going bonkers because i couldnt find the right instructional. The power supply operates under high voltage and current. As switching supplies become ubiquitous in electronic devices today, it becomes that much more important to understand how they work. Apr, 2016 how to repair a switching switch mode power supply. Secrets on power supply repair and troubleshootingsolving problems and failure in switch mode power supplies. Repairing switching power supply modern power supplies are known as switching regulator power supplies. Intermittent issue see what we find this feature is not available right now. Troubleshooting a switching power supply part 1 circuit. How switch mode power supply works smps troubleshooting. Switchmode power supplies power supply fundamentals a typical line connected power supply must perform the following functions. This circuit is used to convert the dc supply into high frequency, high current ac, which by various means. Troubleshooting switching power converters a handson.
Old fashioned linear power supplies based on mains frequency. In most switching supplies, the 110 volt ac input is first rectified by two diodes and filtered by a pair of capacitors. The continuous switching of the capacitor maintains the voltage at the required level. We recently received a switching power supply that failed in the field so we took the opportunity to do some troubleshooting and discuss the process here on. Tips on repairing smps power supplies without published schematics.
A switching regulator does the regulation in the smps. Astron only make an 11 and 15 version peak current of 11 and 15 amps, respectfully of this series. This reference manual contains useful background information on switching power. Troubleshooting switching power supplies by jeff dixon overview this application note provides insight on troubleshooting and taking measurements in switching power supplies. Understanding the functions of switch mode power supply troubleshooting linear power supply is extremely straightforward as opposed to smps or switch mode power supplies. The manual is perfect as a reference guide for computer power supply repair. In this daily drill down, rodrigo zamora gives you a troubleshooting process to isolate these power related problems. Troubleshooting a power supply circuit instrumentationtools.
Dont waste anymore of your precious time to search from the internet to learn the basic repair. Power supply repairtroubleshooting, testing, problems and. A switchedmode power supply switching mode power supply, switchmode power supply, switched power supply, smps, or switcher is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an smps transfers power from a dc or ac source often mains power to dc loads, such as a personal. Secrets of smps repair and troubleshooting switch mode. Never remove the metal cover of the power supply while ac power is connected. Applications of different topologies and their pros and cons are also discussed in detail. And a large part of that detail lies in the practical domain. Power supply problems often masquerade as device or software problems. Blown fuse in general conditions, blown power fuse indicates problems in internal circuits.
Notes on the troubleshooting and repair of small switchmode. Alright, alright, im just jokinghowever, the fact remains that troubleshooting. It is an irreplaceable tool for troubleshooting and repairing electronic equipment by determining performance and health of electrolytic capacitors. In some cases the power supply boots up and attempts to regulate. A faulty pc power supply belies many intermittent computer problems. Secrets of smps repair and troubleshooting switch mode power. The power supply repair is one of the most challenging tasks for an electronic repairer and once you have mastered the circuit and repair technique, to troubleshoot other types of circuit such as the color, vertical, audio, high voltage. View and download rosewill power supply user manual online. Discover some awesome tips on how to repair switch mode power supply smps. Switchmode power supply troubleshooting safety the primary danger to you is from the input side of the supply which is directly connected to the ac line and will have large electrolytic capacitors with 320 v or greater dc when powered often, even if the supply does not work correctly and for some time after being unplugged especially if the power. A technician is troubleshooting a power supply circuit with no dc output voltage.
Unlike other esr meters that only measure esr value this one measures capacitors esr value as well as its capacitance all at the same time. Debugging powersupply startup issues introduction you just received your assembled power supply printed circuit board pcb from the manufacturer. There are several topologies commonly used to implement smps. A technician is troubleshooting a power supply circuit that. Lcd and crt monitor power supplies, lcd tvs, dvd players, and many other electronic devices that contain a switch mode. For the first time, a systematic and thorough discussion of troubleshooting switching power supplies.
A series switching element turns the current supply to a smoothing capacitor on and off. Feb 06, 2011 switched mode power supply repair guide. Its most probably due to a burnt mosfet, the one which can be seen on a heatsink. The power supply fault could be an open start up resistor only or could be even more than ten components burnt due to heavy lightning strike. Never block the ventilation slots and cooling fan air intake window. Switch mode power supplies smps are now standard for the majority of our home appliances. Specific measurements include output ripple, line and load regulation, efficiency, and transient response. Jul 19, 2001 learn to troubleshoot power supply problems by marsha glick in data centers on july 19, 2001, 12. The voltage on the capacitor controls the time the series element is turned. Voltage conversion changing the 115230 vac line voltage into one or more other voltages as determined by application. All you require is a professional to maintain your hand over the process. Troubleshooting switching power converters 1st edition. An140 basic concepts of linear regulator and switching.
Switchmode power supply troubleshooting safety the primary danger to you is from the input side of the supply which is directly connected to the ac line and will have large electrolytic capacitors with 320 v or greater dc when powered often, even if the supply does not work correctly and for some time after being unplugged especially. Repairing switching mode power supplies audioxpress. Troubleshooting and repairing atx power supply brought to you by jestine yong i hope that you have enjoyed the short report of the easy way to understand switch mode power supply. The output voltage is supposed to be 15 volts dc, but instead it is actually outputting less than. This application note, which is the first of a twopart series, explains the basics of different smps topologies. In this ebook, you will learn all my advance troubleshooting and repairing secrets and you can become a professional in switch mode power supplies repair. Voltage fluctuations or surges of power grid often give rise to instant increase of current, which may result in blown power fuse.
Of course, like any good troubleshooters and according to the pcb troubleshooting flowchart we gave the power supply a good visual inspection. Apr 29, 2017 intermittent issue see what we find this feature is not available right now. The stepdown transformer in an smps operates at a high frequency which in turn reduces its volume and weight. Power supply repair and troubleshooting secrets dealing with difficulties and malfunction in switch mode power supply the power supply repair is read more. And a large part of that detail lies in the practical domain, largely because of the typically small number of microseconds of switching periods involved, and the even smaller tens of nanoseconds of switch transition times all these, in effect accentuating various secondorder effects, that eventually end up playing prime havoc with normal.
The green fps products help reduce the systems standby power to below 1watt with the burst mode operation. And a large part of that detail lies in the practical domain, largely because of the typically small number of microseconds of switching periods involved, and the even smaller tens of nanoseconds of switch transition times all these, in effect accentuating various secondorder effects, that eventually end up playing prime havoc with. This is especially useful for switching power supply circuits, where transistors are. Acdc switch mode power supply design guide fairchilds fps products are highly integrated offline power switches with a fully avalanche rated sensefet and a current mode pwm ic see burst mode operation figure below. This application note provides stepbystep instructions on how to perform a broad range of power analysis measurements on your switch mode power supply smps, as. When a pc suddenly goes on the fritz for no apparent reason, checking the pc power supply first may save a lot of time troubleshooting the system. Troubleshooting an unwell astron switching power supply. Smps troubleshooting 3 very startling tips to help you troubleshoot smps. The basics t he power supply is a large metal box, mounted inside the pc that provides power to the motherboard and various peripherals. Troubleshooting a switching power supply part 2 circuit.
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