TechLore - The Tech's Files

Why does a fuse blow?

zapdbf — Thu, 07 Feb 2008 20:58:33 GMT

First off we need to understand what a fuse is. A fuse is a safety device, primarily designed to protect something from fire or damage. A normal fuse is simply a small wire running from one electrode to another electrode and encapsulated in some kind of fire proof casing. A fuse should not be confused with a circuit breaker. A circuit breaker has the same purpose as a fuse, but it can be re-set and used again. A fuse has to be replaced when it blows. Fuses, especially ones found in a television, can be very deceiving and hard to find. They come in many shapes and sizes. Other components like; resistors, or coils, may also do double duty and act like a fuse. This behavior is engineered into the component. A fuse under normal conditions will allow the free flow of electricity to the circuit it is feeding. Normally, if everything is working correctly, the fuse has absolutely no effect on the circuit. If the circuit that the fuse is feeding draws too much current, the fuse wire will get very hot, very fast, causing the wire to disintegrate or burn open in one spot. Once that wire has...

Sony Recall !

zapdbf — Mon, 12 Nov 2007 16:01:55 GMT

From time to time people have been upset because they feel that their tv or electronic device made by sony should have been re-called. In truth Sony will issue in-warranty maitnance repairs or recalls that your device needs. If you registered your product, they will usaly send you a letter outlining the problem and the required repair. Not everyone will receive this letter. Sony has a place on their website where you can type in your model number, and it will tell you of any recalls or other important information about your Sony product. I suggust that you visit this site before your warranty runs out. To see if any updates have been issued for your sony products click below. http://esupport.sony.com/?ref=http%3A//www.sony.com/index.php

The Pixel Kunumdrum

zapdbf — Thu, 08 Nov 2007 00:59:18 GMT

All televisions have a small display unit of the screen called a pixel; a pixel is the smallest picture element on the screen. It will produce a number of colors with varying intensity, comprised of three primary colors red, green, and blue. Take a magnifying glass and get real close to your tv and you can see the three separate colors that form a pixel. On the older crt type of televisions an electron beam was scanned across a set of pixels to illuminate the pixel. The pixel was made up of a phosphor coating that illuminated each of the three pixel elements at different intensities generating the color for that spot. In all of the new modern displays each pixel is a separate electronic component, independent from the pixel next to it. Because each pixel is on its own, it is possible for just one of these pixels to become defective over time. It will do one of three things, it will stick on (always emitting light) or stick off (always black) or intermittently stick on or off. There is no way that a technician can remove the defective pixel and replace it with a good one. If this...

Sony Convergence Repair(My Sony TV has a distorted picture)

zapdbf — Fri, 02 Nov 2007 15:22:36 GMT

There has been a large amount of chatter on Techlore about Sony convergence ic problems. Luckily Most Sony projection tv's no matter what model you have should be similar to my explanation below, Since Sony rarely fully re-engineers a tv what I am about to say will apply to most Sony projection TV's. A service manual is generally not needed to perform the repair. WARNING! If you don't have any electronic experience this is not for you, I assume no liability for any harm that may come to you or your tv. Perform this procedure totally at your own risk. High Voltages exist in your tv and on the boards I am going to talk about, and can have high voltages on them even after the tv is unplugged. What has happened to your tv: What has normally happened is that the convergence output driver ic's either one or both of them has shorted. Causing your picture to be un-converged, The Symptom of your failure can take on many different looks, so one explanation of what the failure looks like will not be adequate. It will be basically one or more (red,Green,Blue) crt's are not aligned correctly, and colored shifted,...

Rain And Your Handheld Device

zapdbf — Tue, 23 Oct 2007 15:59:05 GMT

Water we encounter every day will conduct electricity very well. Even on a very small scale with your hand-held devices. This is a common hazard that we have to deal with on a daily basis and some hand-held devices are more prone to this kind of damage than other devices. So, then why is water such a problem? There are two ways that water can cause damage. One is its ability to conduct small amounts of electricity, so if a drop of water happens to bridge across two pins of a very sensitive ic, the proper electrical paths set by the engineers is altered causing the wrong signals to be sent to the wrong part, even to the point that it can cause the part to burn out. The second reason is more insidious and will not cause your device to fail immediately, if a tiny drop of water just settles on a single copper trace, that trace will be slowly eaten away by the water drop. When the water drop finally evaporates, it will leave a corroded mess that can bridge between two or more electrical points on the board, it can also eat through the copper causing that...

A Warranty Is Not Insurance

zapdbf — Thu, 18 Oct 2007 20:49:39 GMT

They seem to be very similar, both pay for broken things. What a warranty does is to protect the customer from a MANUFACTURER defect. We have customers who don’t either understand this concept or just hope that it will get fixed for free. When you lose control of that WII and launch it through your new plasma television, Warranty will not fix it. It wasn’t designed to withstand the impact of the WII. That is the key! “Wasn’t designed for this”. The same is true for big screen crt televisions that are on the shopping channel all day with the price in a static location on the screen. The manufactures said that these tv’s were not designed for this kind of use, and warranty will promptly decline any claim made on a set that has phosphor burns. A warranty is a liability for a manufacturer, not a profit center. So then the question is why do manufacturers offer a warranty? Besides any lemon law that may exist in your state, Manufacturers don’t have any obligation to provide a warranty. The reason should be simple, to make us believe that the product is built soundly. It gives us the feeling of...