Шура Люберецкий

Оригинал на русском: http://shura.luberetsky.ru/2010/01/25/pro-podsvetku-zhk-monitorov/

Most modern LCD displays use the backlight technique – the semi-transparent image on the LCD panel is lighted from the back, and the visible image is formed by the light passing through the matrix and filters. A rather bright white light source should be used as a backlight, because the LCD matrix is quite dark – comparable to dark sunglasses.

Traditionally cold cathode fluorescent lamps (CCFL) were used for that. This lamps look as thin (2-3 mm in diameter) white glass tubes. The inner surface of the tube is covered with luminofore, and the tube is filled with mercury vapor. When an electric voltage is applied to gas, it is ionized, making the luminofore glow. For CCFL, you need to supply it with high frequency (40-50 kHz) alternating voltage of about 1500 V.

One of the most common failures of LCD panels is breakdown of backlight or invertor – a device which transforms DC voltage of about 12-18 V into AC foltage for the lamp. You can notice that either in partial darkening of the screen, usually near one of its sides, or in complete darkening – in this case you can see the dim image only when you light the screen with a bright lamp.

In authorised services this malfunction is repaired by changing the entire panel, especially in case of notebook screens. That is quite expensive, and the price can be compared to that of a brand new display. Luckily, there are not only authorised services, but a quite large number of “handymen” who are able to replace the backlight or inverter.

Replacing of a backlight lamp is quite easy, and is sometimes possible without full disassembling of a display. It is described in Igor Pichugin’s article at RadioCat website, as the article is in Russian, I’ll briefly retell it.

The lamps are mounted along a side of a display in special casing. To dismount the casing, you need to disassemble the panel – take off the metal case and the glass panel with some electronics. The electronics is a thin (0.5 – 1 mm) circuit board, connected to the glass panel with some flat ribbon cables. The cables are protected with sticky film, which you have to unglue carefully (never cut it! if you accidentally damage the ribbon cables, you will be unable to repair them).

For demonstrating of “classic” CCFL technology I use the LG Flatron L1970H display.

The disassemly begins with removal of a stand. You need to take off a plastic cover in the back, which hides the connectors and screws of the stand.

After removing the stand we can disassemble the plastic case. The front bezel is mounted on several clips and can easily be removed.

The LCD module is in its metal case. Through the holes you can see the transformers of the invertor with scary cautions.

Unscrew the case and remove the metal covers.

We can see the control board of the display and a separate inverter board.

The control board is connected with the decoder of the matrix, the latter is covered with protective film.

The decoder is connected to the matrix with thin flat ribbon cables. It you have to take off the matrix, you have to peel the protective film carefully – the damaged cables can not be restored, and any damage to them renders the matrix unusable.

The inverter, if broken, often can be changed to a compatible one. You need to know the supplied voltage and the number of the lamps. Also, the inverter is quite big, and often can be repaired with widespread tools.

The lamps are connected to the inverter by standart plugs.

In this display you can unmount the lamps casing without taking apart the whole panel. Undrive a screw…

…and pull the lamps casing.

The lamps are mounted in pairs. You can distinguish an old lamp by a dark ring across its end. When the lamp ages, the ring gets darker an darker.

I needed the lamps to test the inverter of a notebook PC Fujitsu-Siemens Amilo M7800, which had symptoms of backlight failure. The authorised service charged incredible money for replacing the panel, so I decided to use Igor’s article to revive this PC cheaply.

To access the panel, you should take away the besel. It is mounted on clips, but sometimes there may be screws fixing it.

In the lower part of the display one can see the inverter in protective case.

To test the inverter, you should connect a working lamp to it.

If the inverter of a notebook appears broken, it is considered unrepairable and is replaced by another one. If you can not find the original part, you can try to use “compatibles”, which can be found in many shops, including online, such as Dealextreme.

When replacing the inverter one should be sure about control signals of dimming and switching on/off. The cable of the inverter usually contains DIM and ENABLE signals, which change from 0 to about 3 V (always measure actual values!), 0 V means disabled/zero brightness, 3 V means enabled/full brightness. Usually their proper commection is not mandatory, but it allows to use power-saving features.

To replace the lamp we need to take off the LCD panel. Unscrew its mounting to the plastic cover and hinges and pull out.

Take off the metal guides on the sides of the panel.

In this panel you can get to the lamp without full dismounting. You only need to take off one side of the metal frame and open the plastic case.

The following seemed to be obvious – go to a spare parts shop, buy a lamp and put it on its place. But there were no shops with the lamps of the needed length in Moscow. At Mitino market I was advised to use a LED line designed specially for backlighting LCD panels.

A width of this LED line is about 3 mm. The diodes are grouped by three, with the length of each group about 15 mm, so you can cut the needed length.

Today, when ultra-bright white LEDs are easily available, LED backlight is installed in some LCD displays and TVs. Really, anyone can touch this breakthrougth technology, installing LED line backlight instead of a broken “lamp”. The 300 mm line which I bought costs about 8$ (250 roubles, which roughly equals the cost of a spare lamp).

The LED line perfectly fits on its place.

To test the LED backlight we need to connect it to any suitable power source (we need 12 V DC, observe polarity :) ). The unplugged screen should glow bright white.

Assemble in reverse order.

Instead of a non-needed inverter you can install a schematic like this:

The resistor values may vary in different notebooks, so I do not write them here – knowing DIM/ENABLE parameters and supply voltage, one can easily calculate them.

Finally, a few words on disadvantages of home-made LED backlight.

First of all, LED spectrum differs from CCFL spectrum. If you need accurate color reproduction, i. e. on a high-quality graphic workstation display, you should use only CCFL.

Also, there exist “smart” inverters which are controled not by analog voltages but by some digital bus, usually I2C, but more exotic variants exist. If such inverter is absent, the LCD may automatically switch off.

The third and main bad feature of this “do-it-yourself” backlight is non-uniform lighting near the lamp.

In the photo you can notice that the lower part of the display has some darkenings, and the lower right angle is completely dark as the LED line happened to be short a bit.

In any case, replacing a CCFL lamp with LEDs can be a cheap and easy way of restoring LCD displays. The drawbacks are not critical, and in case of non-standart lamp lengths it is quite a reasonable decision.

Недавно в жежешечке кто-то выложил видео с чеченцами, расправляющимися с русскими солдатами. Жежешечка дружно решила, что все это, так сказать, абсолютно нормально и законно. А вот elyssov считает иначе, и выложил пару роликов, изображающих кровавую расправу с американцами в Ираке с целью “доказать” обратное.

These videos contain bloody massacre of American soldiers in Iraq.

Просьба всячески пиарить оригинальный пост с целью вывода его во все мыслимые и немыслимые топы:

http://elyssov.livejournal.com/1246.html

Скоро ли набигут ребята из Abuse Team?

ALL HAIL LJ ABUSE TEAM!

In December 2008 on a Russian HAM radio forum a new Russian-designed receiver was introduced. It is called Vega RP-007, or, in Russian, Вега РП-007. The name utilises a well-known Soviet electronics brand Vega, together with a number starting from zero, which means “highest class” according to GOST standarts. Well, it is really a great receiver.

The receiver was ordered by Russian military as a replacement for “political officer receiver” Sinitchka MP-64 (Синичка МП-64), that caused its “camouflage” design and anti-shock, dust- and waterproof body. Also, the receiver has a built-in flashlight and can be powered from any voltage source from 6 to 30 volts.

As you can see, the package of the receiver is not a carton box, but a very useful plastic case, where all the needed accessories can be carried. The package includes headphones, two power adapters – for 12-30 V DC and 220 V AC, both of them could be used as chargers, an external extra-long antenna on a reel, 4 AA rechargeable accumulators and a cloth bag for the receiver.

The schematic of the receiver is traditional for high-class all-band receivers, it is a superheterodyne with two frequency transformations. First IF is 55.845 Mhz, second IF – 455 kHz. Though, the receiver is slightly improved compared to popular Degen 1102 and Sony 7600. Better electromagnetic shielding is added, which reduces interference.

The technical characteristics is similar to other receivers of comparable class. There are MW (530-1710 kHz), SW (3000 – 29999 kHz) and two FM bands: Russian (66-74 MHz) and “traditional” (88-108 MHz). The tuning step in MW bands is 9/10 kHz, in SW – 5 kHz with possibility of entering the frequency manually with 1 kHz step. In FM, the automatic tuning step is 100 kHz, and the manual step is 10 kHz. The sensitivity is quite good: 20 uV on SW, 1 mV/m on MW, and 10 uV on FM bands.

As any PLL tuned receiver, Vega RP-007 has memory for frequencies – total 300: 100 for FM, 100 for SW, 100 for MW. Also, there is an alarm clock with its separate memory cell. We have a full set of connectors – the external antenna, the headphones and a line-out. All the sockets can be protected from dust with rubber stoppers.

The only disappointing feature of the receiver is its size and weight. It is quite big due to its protected casing – 190 х 119 х 35 mm dimensions, and 720 g weight. Though, it can be used in any environment – the working temperature is from -10 to 40 degrees Celsius, the case is dust- and waterproof and can stand more than 100 kg load.

Also, there are no rotating or protruding parts, all the control is made by the waterproof keyboard. This can seem unconvenient, but try to imagine the receiver being thrown in a wall. I am more than sure that all the valcoders and beatiful knobs of a “civil” receiver will not survive that, while Vega will continue to work allright, thanks to impact protection. The telescopic antenna can be totally hidden inside the case.

The price of the receiver is unannounced, though it is known that one of the members of the forum has bought this receiver for 4000 roubles, that is around 120-130 $. The production was limited, but there were talks of an improved version, with SSB and 12 kHz DRM converter, so you can connect a computer with some software, like Dream, to listen to digital shortwave radio.

Оригинал на русском: http://shura.luberetsky.ru/2008/12/13/delaem-usilitel-dlya-kolonok/

The test of an anti-crisis loudspeaker proved that it does not work fine with a MP3 player as a source. So we will add a simle amplifier, like the one in “PC multimedia speakers”.

I have bought a Samsung KA2026 chip, as it is one of the simplest and cheapest chips for a small amplifier.

KA2206 as is

This chip costs about 0.75$ (18 rubles) in Moscow. There are many pin-to-pin compatible chips by different vendors, the most popular are: LA4180, LA4182, LA4183, LA4550, LA4555, LA4558, TEA2025. All this chips contain a two-channel audio amplifier, that also allows usage in a “bridge” circuit – with combined power of two channels. The parameters are good for a “multimedia system” – with 9-12 V supply the amplifier has a power of 2 W on a 8 Ohm load with 10% non-linear distortion. By the way, the “300 W” stickers on Chinese boomboxes and active loudspeakers are all lies. Most of them are built around a similar chip, that can’t deliver such power.

The datasheet stereo amplifier circuit is as follows:

The circuit

You will need just some electrolytic capacitors, which I get by desoldering old PC motherboards. You don’t even need to make a PCB – all can be done by point-to point wiring on a piece of copper-clad board.

Point to point - that is cool

I used the wires from a twisted pair cable for the audio connector and power wires – it’s a real pleasure to tin and solder them.

The amplifier is finished

After finishing the amplifier, we connect the speakers – the left and the right channel. As the power source, you can use a PC power supply – it has a 12 V channel, or a 9 V battery. The sound quality is similar to the chinese “active speakers” with “300 W PMPO” sticker.

In the second part of the video you can hear the “Corrosion of metal”, yeah!

Оригинал на русском: http://shura.luberetsky.ru/2008/12/11/antikrizisnyjj-dinamik/

Today, when all the world is struck by an economical crisis, a well-known Russian rock musician Pauk (Spider) advises to do some downshifting – for example, to go to the village and to grow pigs. Well, in the village you will need to listen to “Corrosion of metal” – the band of Pauk, so you need a powerful audiosystem to produce real hell madness. Today I will tell how to make cool loudspeakers out of trash. The original designer is Jose Pino of Mexico.

Tools and materials

All you need is some magnets, paper, piece of cardboard, thin enameled wire (I will tell where to get it from) and a styrofoam plate from the nearest supermarket.

Russian Moment glue - the joy of a glue sniffer

Also you will need some glue. I used “Moment” for paper and UHUpor for foam.

The magnets

You can get the magnets in the shop or just steal them from the office.

So, let’s start. You should turn some layers of a paper band on a magnet (I used three rather weak magnets put together) and glue it to get a paper cylinder.

Magnets and paper

Then make a second layer, but not glue it to the first. You should get two paper cylinders – a smaller and a larger one.

Paper cylinders and a magnet

Now throw away the smaller one, and the bigger will become a base for the coil of enameled wire. You will have to use the thinnest wire available, something like 0.1 or 0.2 mm – or AWG 32-38.

If you try to buy enameled wire, it will either be very expensive, or you will buy a several kilometres hank of cable. Nobody buys it, and if you need enameled wire, you could search it in old transformers, electric motors, CRT TVs and monitors and other similar things. In my box full of trash I found an output transformer of an old radio receiver “Mayak-202″, which had the wire I needed.

This transformer is five years older than me

Glue the paper cylinder to the centre of styrofoam plate and begin to wind the coil, leaving a free piece of wire of 5-7 inches. You could put the magnet inside not to crush the cylinder.

Winding the coil

The resistance of a coil should be from 8 to 32 Ohms. I made 100 wounds and then protected it from loosing with a piece of Post-it paper.

The coil is ready

After that I covered the ends of the wire with solder (you need not to crimp the insulating enamel – it will burn itself from the soldering iron heat) and measured the resistance, getting some 13 Ohms.

Checking the coil

Now we only need to hang the loudspeaker on some base. I used a big piece of cardboard, which can hold two loudspeakers and a simple amplifier. Take two business card-sized pieces of paper, fold them and glue to the speaker:

Also, I have cut the unneeded part of the paper cylinder

Now we make two holes for the wire in the cardboard and glue the suspension and the magnet to the speaker base. Be careful not to glue the magnet to the coil or the plate – the speaker will not work then!

Assembled loudspeaker

The loudspeaker is ready! To check it, you only have to take a battery and touch its terminals with the ends of the speaker wires. You should hear “clicks” when touching.

The sensitivity of the speaker is quite poor, so you will need an amplifier to build a really powerful anticrisis stereosystem.

This is the first post in the English section of my site.

This section is created specially for translations of my best posts, and is available by its adress – http://shura.luberetsky.ru/category/english. Sorry, no RSS or crossposting yet.

It will contain posts about electronics, HAM radio and, maybe, some photo reports. Enjoy!