| |
| |
|
Hardware Information |
|
|
|
Testing a Transformer- How To Accurately Test A Transformer
There is two types of transformers in the market- linear transformer and switch mode power transformer. The transformers design is different. Sometimes it is just referred as ac transformer. Linear transformer mostly used in radio, project kits, VCD and etc while switch mode transformer can be found in Monitor, Tv, Fax and so on. A transformer consists of two or more coils wound on the same core. For power transformers, the core material is usually iron. For a radio-frequency transformer, the core material is usually ferrite or air. The basic property of a transformer is to change AC voltage. A transformer cannot change direct current voltage. A step down transformer has a lower AC output voltage at its secondary winding than the AC input voltage to its primary winding. Conversely, a step up transformer has a higher secondary than primary voltage. The transformer laminations or coating of shellac, enamel or varnish is to insulate adjacent turns from shorts between winding. I will not go too details about how transformer work and transformer calculation as you can read more details from most electrical and electronic transformers books. How to test transformers: Transformer failures are relatively rare in most electronic equipment, compared with other components. If too much current goes through a coil or winding, the winding heats up and can either open up completely, or the insulation between turns of wire can break down, causing the coil to be partly or completely shorted. Just like a coil, you can check continuity of any primary or secondary transformer winding. The actual value of DC resistance you read is rather meaningless, but at least you will know whether a winding is open. Checking linear transformer is quite straight forward. Apply the ac voltage to the primary winding and expect output voltage at the secondary side. No or low output voltage means the transformer winding has open or shorted winding. Look for any evidence of overheating, such as darkened or blackened areas or a burnt smell. About how to test a power transformer-it is a little bit complicated. You cannot apply ac voltage to the equipment and expect the desire output at the secondary side without connect to load otherwise over voltage will happen (because you have removed all the secondary load) and will blow the power section which consist of power fet, pwm ic and etc. Swith mode power supply are designed to run with load while linear transformer can be test without load. The best way to test a switch mode power transformer is first remove it from the board. Check only the primary winding as secondary winding failures are exceedingly rare. How do we know which one is the primary winding? Trace from the big filter cap the positive pin to see where the circuit goes. It will go to one of the pin of the transformer. Then look for the power fet middle pin which is the Drain and it will lead to another pin of the transformer. This two pins is the primary winding of the transformer. Checking the resistance of the primary winding only can reveal whether it is open but it cannot check if it has developed a shorted winding. Only by using a ringer test you will know if it shorted or not. A shorted turn in the primary winding can cause the power section to blow. The cheapest ringer tester that i came across is Dick Smith LOPT METER or flyback tester. Just connect the probes to the primary winding and the result are instantly seen from the Led bar graph. 4-8 bar represent a good winding, 1-2 bar represent partial short and if the led goes off means there is a heavy short in the winding. Besides checking the transformer it can be use to check B+ COIL, horizontal yoke coil and flyback primary winding and ballast (choke). The expensive ringer tester is from sencore equipment. Sencore LC102 and LC103C besides checking capacitor it also have the capability to check all kind of winding. Whether it is a low voltage transformer, high voltage transformer, current transformer, pulse transformer, electric transformer, custom transformer this equipment will be able to check and test it. If you do not wish to invest on this tester you may use a light bulb to check it. Remove one of the primary winding pin and connect a 60 watt light bulb. One end to the circuit while the other to the transformer pin. If the bulb light and didn't goes off suspect a shorted winding and if the light goes off, the winding is ok. Transformer repair is not easy and it require a good skill to do it. Most of the transformer repairer preferred to rewind bigger winding such as fan, car alternator and starter. Swith mode power transformer is a little bit difficult to rewind because of the small size and low price. Jestine Yong is a electronic repairer and a writer. For more information about electronic repair please visit his website at http://www.noahtec.com/electronic-repair-articles.htm
MORE RESOURCES:
Hardware - Google News |
|
|
|
RELATED ARTICLES
Personal Asset Preventive Maintenance Software Personal asset preventive maintenance software exists to help people manage and maximize the value of their assets. Common types of personal asset preventive maintenance software deal with taxes and investments. How to Add or Remove an IDE ROM drive CD ROMS - If you're adding or removing an internal cd-rom, dvd-rom, or just about any internal ROM that has an opening CD door, read on. Almost all IDE devices such as CD-ROM, DVD-ROM, etc. Two Essential Accessories For Notebook Computers A Good Notebook BagForget those that are bundled with your notebook computer. Get yourself a good notebook bag that is well-padded both on its load-bearing straps, and 100% around the notebook itself. High Definition DVD High definition DVD, also known as HD-DVD (which actually stands for High Density DVD), is one of two competing high definition storage format - the other being Blu-ray.The need for a new, high capacity storage format, has been primarily brought about by the rapid rise in popularity of HDTV in Japan and the US. How To Buy A Printer That Won't Break The Bank OK I confess I've bought at least 10 inkjet printers in the last 5 years and finally found one that I really like. I'm not going to mention the brand here but I will tell you what the must have features are for me. Pixel Disruption To Cause Nausea From User of Computer Screen As we study the issues associated with teaching kids in the classroom we find that fluorescent lighting can plague the learning abilities. A slight flicker from such a light can cause disruption in normal brain patterns. Laptop Notebook - Inexpensive Business Laptops Laptop Notebook - Your Portable OfficeIn much of today's business world, portability and mobility are the keys to success. Having a laptop notebook computer provides business men and women with portable computing capability, and these notebooks help them take their mobile business functionality to a new level. How To Choose The Best Gaming Laptop The gaming laptop is coming of age! It is steadily increasing in popularity as performance quality goes up. Gamers now regularly consider laptops or notebooks when searching for that perfect gaming machine. ESR Meter - The Capabilities To Check Beyond Electrolytic Capacitor There is something good about esr meter because besides electrolytic capacitor it can be use to measure other type of capacitors such as the non polarity capacitor. From esr meter specification, it is usually mentioned only checking the electrolytic type. A Review of HP Laser Toners Hewlett-Packard is, along with Brother and Samsung, one of the most readily available brands of laser toner. This is due, in part, to the fact that HP was first to release a laser toner inexpensive enough to catch the attention of the average consumer, in 1984. SED is Coming One of the bigger challenges facing display manufacturers is to develop a picture with the same warm characteristics as Cathode Ray Tube, but with far less weight and size.The disadvantage of CRT, however is the size, weight and power consumption. Discover Everything About Wholesale Bar Code Reader And Software! It is a given fact that buying wholesale would make us save more money than buying individual items at retail. Purchasing in bulk means more profit for the seller that he could be afforded the leeway of granting discounts. How To Refill Your Ink Cartridge Forget about emptying your wallets every time you see the blinking light. Quit worrying and start doing it yourself! It's an easy process that won't take you more than five minutes. How To Purchase A Quality Laptop Computers Case So you finally have that new laptop you have been drooling over for the past 3 months, only there is one problem -- You don't have a case for it. You've probably already laid down over a grand for the notebook and you're telling yourself that you don't want to spend another $70 for a case. Three Must Have Accessories For Notebook Computers An Optical MouseNotebooks are normally equipped with touch pads which can be awkward. There's no substitute for the mouse. Basics of RAID A couple of the recent Tech Tips from www.geeks. Ink Cartridge Recycling 101 Let's take a moment to think about the topic of ink cartridge recycling. In our modern world we just keep throwing our trash away without sparing it a second thought. How to Read Zener Diode Code Many technicians are confused on how to really read a zener diode code. There are many types of code number indicated on it's body. 5 Ways To Backup Your Data... The data on your hard drive is the most critical item inside your computer, and the only item which can not be replaced. It may be an unwanted hassle and expense to replace a defective memory module, monitor, or processor, but there is no replacing data once lost. Ten Ways (plus 1) to Save on Printer Ink and Toner Cartridges Are you getting tired of the high cost of printing? You're not alone. Many consumers are up in arms.
|
| home | site map |
| © 2006 |
