The Right Way To Discharge Capacitor In Switch Mode Power Supplies by Jestine Yong
Switch mode power supply contain some large filter capacitors that can hold dangerous charges even if the unit has not been used for several days. Typical values of this type of filter capacitor are 220uf 250volt and 330uf 400volt! If you are going to work on the power supply circuits, it's a... The reason for not using the screw driver to discharge a capacitor is because -the printed circuit board or circuitry can be damage due to the spark generated while discharging the high voltage capacitor.

History of the Computer: Cooling, Part 2 of 2 by Tony Stockill
Computer manufacturers specified the heat load required to be handled, the required flow of conditioned air, and the temperature to be measured at the cabinet entry points. Most systems were installed on false floors, with a space of about 1 meter or 3ft below the floor. ... The Backplane was a large multilayer printed circuit panel, of varying size, depending on the system, but normally around one metre or 3ft square. ... The computer logic circuits were assembled on multilayer PCBs ( or PCAs - Printed Circuit Boards or Arrays) which were 'plugged in' to the backplane.

Choosing a PCB Printing Solution by Chuck Raymond
The electronics Printed Circuit Board industry is evolving as new production technologies become available at low cost. Direct digital printing is making inroads into the traditional photolithography and screen printing processes that have been used to manufacture PCB for the last twenty years. ... A newer approach is to have the circuit boards printed with ink patches, the ink patch is then selectively removed (ablated) by the laser creating the mark to be printed. ... The goal is to print a unique mark on each board that can be used to identify the board.

What is ESR Meter? by Jestine Yong
All capacitors have a certain amount of resistance to the passage of AC current. ESR (Equivalent Series Resistance) is the sum of all internal resistances of a capacitor measured in Ohms. An ideal capacitor has ZERO ohms ESR. From the diagram below you can see a resistor in series with a... High ESR will cause complete circuit failure, over heating of capacitor, loading of the circuit, overstressing of other circuit components and other undesirable effects. ... » Short-circuit in the track, usually trace to the components - You can use the ESR meter to locate short-circuits on printed...

ATX Power Supply Repair And Troubleshooting by Jestine Yong
Customer ATX power supply came in with the complaint of intermittent no power. When testing it with power on, I could see that the fan is not rotating. Not only that, some filter capacitors also became bulge because of the heat accumulated inside the power supply. ... Scrap it off with your test pen and use Thinner solution to clean the printed circuit board. ... Diodes run a little bit hotter in filter circuit than diodes in other circuits due to the high current present at the secondary output line.

How To Read SMD Resistor Code by Jestine Yong
SMD stand for surface mount device and if you repair LCD monitors, you would come across lots of SMD components. CRT monitors rarely use SMD thus it is quite easy to find out the components value. In this article, I’m going to talks about SMD resistor code and how you could calculate the values. ... There are two types of surface mount resistors used in an electronic circuit board-the 3-digit and 4-digit code SMD. ... Surface mount resistors is very much smaller in size than the normal carbon film resistor and because of this the numbers and letters were stamped upon or printed on the top...

How to Read Zener Diode Code by Jestine Yong
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. The look and shape of a zener diode sometimescan be mistaken to be a normal signal diode. To differentiate it, is by looking at the codenumber on it's body- whether... However, from my experienced some printed circuit board the marking of 'D' also can represent zener diode. ... The only way to find out is by referring the code number printed on the component's body from a semiconductor data book.

Small Wonders: Single Board Computers by Paolo Basauri
What are Single Board Computers When most people think of computers, the image of a PC or laptop comes to mind. Some may even recall the football field size computers of the 1960's and 70's before the emergence of the PC. Very few people would picture single board computers , even if there was... A single board computer is the terminology used for a printed circuit board that contains a processor, memory, I/O (input/output) and a clock. ... Usage of Single Board Computers Also commonly referred to as embedded computers, single board computers are used in products from airplanes and...

Laser Marking of ECC 200 2D Matrix Codes on Printed Circuit Boards by Rick Stevenson
Manufacturers of electronic devices, from home audio equipment to automotive keyless entry systems, are increasingly seeking a reliable, cost effective method for uniquely identifying and tracking products through the manufacturing cycle, sales distribution and after-sale warranty verification. ... The code must be durable enough to survive manufacturing processes including wave solder and board cleaning, must not affect circuit performance, and must store information in the small space available on real-estate conscious printed circuit boards.

How Data Is Stored On A Hard Drive by Jason Perry
When a file is saved on a computer, the data is stored on the hard disk platter's magnetic coating. This magnetic coating on the platters is the 'glue' that keeps your data. Any damage to that magnetic coating means that there is data loss as each piece of missing coating contains data. ... Firmware Firmware is the program instructions located on the chips on the Printed Circuit Board (PCB). ... Printed Circuit Board (PCB) The PCB of the hard drive is the electronics of the hard disk that manages and operates the hard drive.