We turn the monitor into a TV. DIY translucent display Which monitor is better

Surely many of you, having bought yourself a new monitor, have wondered what can be done from an old monitor. I was also puzzled by this thought, although I was puzzled by this thought for a very long time, but then there was not such a large selection of different devices. But the Chinese brothers are not asleep and are inventing devices with an unprecedented combination of capabilities. One of these devices was a TV set-top box, which I purchased to add capabilities to my old TV.

• Nexbox A95X TV Box: making Smart TV from a regular TV

But having connected it to the TV set-top box, I was a little disappointed in the clarity of the picture, the set-top box was a little difficult to use, but it helped possibility of remote control from a smartphone or tablet. As a result, the set-top box exceeded my expectations because it was used to watch a bunch of videos from a home server, but the functionality of the set-top box turned out to be much wider and in the end this small box turned a simple TV into computer controlled by remote control. Why am I doing all this? Read on and you will understand everything.

Since my parents do not like to throw away equipment, the Samsung SyncMaster monitor (CRT monitor), after purchasing an LCD monitor, was carefully taken to storage in a barn at the dacha and safely forgotten there. Once again, while putting things in order in the “junk storage”, my father came across a monitor and wondered whether it was possible to watch news on it at the dacha. But he could only get the answer from his advanced son, that is, from me, which he did by calling me one evening.

The monitor itself:

Because a monitor, to put it simply, is a kinescope with a scanner without a radio receiver, which is in the TV, and without a sound system. In other words, it is a TV, but simplified and devoid of some parts. In fact, the monitor contains only a power supply, a scanner and a video amplifier. The only signal source is the VGA(D’SUB) plug, which supplies an analog signal. What does this mean? This means we just have to find a device that will be the source of the signal.

If you have a newer monitor, then it’s probably even easier, because some monitors, if we’re talking about LCD, were equipped with speakers, and newer ones even have an HDMI input. If you have one, then you have a very wide choice of options on how to make a TV out of a monitor.

First experiment: Smart TV from a monitor

Remembering that I had an adapter from HDMI to VGA lying around, I decided to look for it and, having found the adapter, I took the set-top box and went to my parents. After wiping the monitor from dust and dirt, we connected it to the network and then to the set-top box. Despite the small diagonal, using the set-top box was very, very comfortable due to the clearer picture, since the monitor, unlike a TV, is designed for high resolution and the relatively small font is easy to read.

HDMI to VGA adapter

Now you’re probably thinking: “Cool, I’ll buy myself a console!”, but don’t rush. This was just an experiment because we don’t have sound, VGA only provides a picture. Therefore, if you want to go this way, you will have to purchase an HDMI to VGA adapter with an audio output, something like this:

You can order a similar adapter on Aliexpress, here is a link to the seller: buy an HDMI-VGA converter.

When you go to the product page, all you have to do is find the adapter that suits you, it’s not at all difficult, the main thing is to pay attention to the fact that the adapter has a power connector and an audio output.

Thus, we can make a “smart TV” from a monitor, but we will also have to buy active speakers, which will also have to be connected to the audio jack on the adapter. As a result, we will give the monitor a second life and get a good option for the kitchen or work.

Advantages

Within the dacha, there are no advantages due to the lack of full communications.

Flaws

1. This set-top box is useless without the Internet.
2. Cost of the set-top box.
3. The need for an adapter.
4. Lack of speakers.

Second experiment: ordering a special TV tuner

Since the place where the barn is located is a place remote from communications and, accordingly, there is no Internet there, the set-top box could not function fully there. In addition, the old father was no longer eager to master another high-tech device and asked to find a TV receiver with a remote control for it.

I present to you a wonderful device that makes a TV from a monitor:

But against the backdrop of recent events with digitalization, this set-top box has lost its relevance.

Digital TV set-top box

Realizing that the presence of digital TV support may be critical for some people, a similar set-top box was found, but with different parameters. You can still connect a monitor to it, but it is no longer possible to connect a computer, and there is no audio output or built-in speaker, which means you will have to connect external speakers.

As you can see, it doesn’t look much different from the previous version, but that’s until we look at the back panel.

As you can see, there is still the same VGA, but in addition to it there is also HDMI. By the way, if you connect this set-top box via HDMI, the sound will come through it. For example, my TV in the kitchen has HDMI, but it does not have digital TV, and if you connect such a set-top box to it, the sound will come from the TV. In addition, this set-top box was also equipped with a USB connector, which makes it possible to watch videos from a flash drive and more.

Just like the first version of a TV tuner for a monitor, this set-top box has RCA (CVBS) sockets.

But unlike the first set-top box, where it is an AV input, in this case these sockets are an AV output, that is, this set-top box, in addition to a monitor and relatively modern TVs, can also be connected to very old TVs.

Features of the console

Since the set-top box accepts digital TV, in addition to everything else, we get a lot of goodies. But first we need to find channels, this is done simply. Press “menu” on the remote control and use the volume buttons to select the appropriate menu item (see photo):

Select “auto search” and press the volume up button. We see the picture:

After some time we will see the found channels and radio stations:

The search for channels is completed, as you can see there are 20 of them in our city, in other cities the number of channels may be different.

By pressing the “info” button on the remote control, you can see what is going on and what will happen next. If you click this button again, you will see more detailed information:

Using the “up” and “down” buttons we switch between gears, and with the yellow and blue buttons we scroll through the description if it is not completely displayed.

To display the program guide, we need to press “EPG” on the remote control:

Use the “left” and “right” buttons to scroll through the channels, and use the “up” and “down” buttons to scroll through the programs.

And here the most interesting thing awaits us. If we press the “OK” button on a particular gear, we will see a strange picture, but if we press the red button, we will see this:

This is adding a schedule for recording a program. Click “OK” again and the task will be added to the queue. The most interesting thing is that we can easily turn off the set-top box, it will turn on itself and record the program. The only thing needed to successfully complete this task is the presence of a flash drive in the USB connector of the set-top box.

A flash drive is also necessary for the “timeshift” function, or “pause” in Russian. Yes, you heard right The set-top box can pause TV. But the set-top box will not be able to keep the TV paused for a long time, since the volume of the recorded stream is limited by the settings of this function. By default the volume is 1Gb, but you can increase it. This is done in the menu:

To do this we need to select “PVR Configure” and click “OK”.

Select “Record device” and click “OK” again.

Actually, here we select our flash drive, and just below we set the amount of memory available for recording.

You've probably wondered why choosing a flash drive if there is only one connector. Nobody forbids us to connect a USB-hub to the connector, and to it a flash drive, an external hard drive, and a card reader.

Three radios are a nice bonus:

Flaws

1. No audio output
2. There is no built-in speaker, you will have to connect external speakers
3. Unable to connect computer

Advantages

1. Digital TV reception
2. USB availability
3. Availability of HDMI
4. Availability of AV output

In general, to summarize, we can state a wide range of options. The option with an Android set-top box is suitable for those who want to turn a monitor into a TV for the kitchen or other room where there is access to the Internet. Two options for a TV tuner for a monitor are suitable for those who do not want to depend on the Internet and have a very simple solution for watching TV on a monitor. The first option of a TV tuner is suitable for those who want to supplement their computer with the ability to watch TV, and the second option is suitable for those who simply want to give a second life to the monitor and be able to receive digital TV.

Despite the fact that progress is advancing by leaps and bounds, you should not throw away seemingly unnecessary, outdated things, as we see they can still serve you, but in a slightly different capacity. You just need to buy an additional device and a useless thing becomes not only useful, but also acquires an incredibly wide range of capabilities.

Modern electronics stores offer an extremely wide range of television equipment: from budget models to expensive new products. However, not every consumer can afford to purchase a new TV.

What is the way out of this situation? It’s all very simple, convert the monitor into a TV, especially since it’s really not difficult to do. Firstly, today probably everyone has a computer monitor. Secondly, even if it doesn’t exist, a new one is still much cheaper than a TV device.

How to make a TV from a monitor? There are several different ways. Anyone can set up a TV with their own hands, the main thing is to follow the instructions. In the future, it can even be used to receive cable channels.

Monitor as a TV

Many may think that turning a monitor into a TV is impossible, but this is not so. To implement this plan you will need some free time. Let's start with choosing a monitor - which one is best suited for such functions?

Experts have conducted extensive testing, checking the performance of a huge number of different monitors, we invite you to familiarize yourself with the results of the study in order to make an objective decision. The leading position is held by the popular South Korean manufacturer Samsung. Converting such a display into a TV is quite simple.

Second place was shared by Sony and LG, offering consumers updated screens with exclusive designs. You can use a computer monitor as a TV, regardless of the manufacturer.

When using a monitor as a TV, you need to take into account such a parameter as screen resolution. Naturally, if it is high, then the image quality will be appropriate.

Perhaps the main difficulty for a beginner will still be the lack of special skills. For example, not everyone will be able to solder a module or connect a component. To avoid mistakes, follow the instructions or seek professional help. You don't need a system unit, the main thing is that you have a screen and a power supply for it.

TV from an old CRT monitor

Cathode ray tube displays fell out of favor with the advent of liquid crystals. However, few people sold or threw out CRT monitors that had gone out of use; prudent owners hid them, as they say, “for later.” Actually, today the moment has come when you can make a TV out of an old screen, breathing a second life into unnecessary equipment.

How to make a TV? We answer the main question, which is undoubtedly of interest to absolutely everyone. The easiest way is to remove the control unit and graphics card. You also need to purchase additional components; they can be found at any TV equipment store.

The main condition is the presence of a VGA connector; without this interface, turning an old CRT monitor into a full-fledged TV device will absolutely not be possible. However, all old screens were equipped with this port for connecting a PC system unit.

If you know absolutely nothing about connection diagrams and basic computer components, then it is unlikely that you will be able to turn an old monitor into a TV; certain skills and knowledge will still be required to achieve the task.

The created product requires the following components and components:

1. The most important functional device of television equipment is the module responsible for adjusting the color of the image. The quality of the broadcast image depends on the correct operation of this node.

Color module from AIWA TV-1402KE TV

1. Radio channel – this module selects intermediate frequencies among all incoming signals, necessary for television broadcasting.

Radio channel modules 40-32V6GM-NIUI2XG

1. The control unit is a part responsible for setting up and controlling the TV in manual and remote modes.

Samsung TV control unit UE32F4500AKXKZ

To make your own TV, connect the missing nodes and insert them into the screen body, after connecting them with cables to other basic modules. It is possible that to enhance image quality you will need resistors; they need to be soldered. A comprehensive audit is then carried out.

TV from LCD monitor

The modern consumer is gradually abandoning the desktop PC. It’s not surprising, because you can buy more compact and no less functional laptops and netbooks. Therefore, if you still have one, don’t rush to throw it away or sell it, because you can make a TV out of it.

Again, first you have to visit a store or radio market to purchase the components necessary to implement this idea:

• splitter and cord for connecting digital television;

• antenna and cable for connecting it.

To connect a new TV, you will need at least 2 sockets - for the tuner and the power adapter. Connect the antenna cable and plug the plugs into the outlet. You need to attach the tuner and power adapter to the back.

The tuner is equipped with a built-in speaker, its sound will fully satisfy the needs of the average user. Aesthetes and music lovers will have to additionally purchase an external speaker system to expand the sound range. What options? For example, you can take a soundbar or DC with a subwoofer; even ordinary speakers will do.

A TV from an LCD monitor will pick up channels perfectly, but TV broadcasting in HD quality will remain unavailable - perhaps this is the main drawback.

If we compare the image quality of liquid crystal and CRT displays, then the advantage is on the side of the former.

How to make a TV with a high-quality picture from a monitor? When making a TV from a monitor, you must consider several important points that largely determine the image quality:

• signal response time;
• viewing angle;
• illumination;
• depth of dark tones;
• contrast.

The LG 710 monitor, like LCDs from other manufacturers, is characterized by a long response to the signal. The viewing angle is also very small. These are too significant shortcomings. The bottom line is that the broadcast image will be of high quality as long as you sit clearly in front of the screen; a slight tilt will cause black spots to appear and the picture will be distorted.

It is impossible to solve problems associated with insufficient black depth, which is why LCD monitors have lost the competition to LED displays.

In most cases, tuners are connected to the TV via a VGA connector. However, if the required interface is missing, you can always use an adapter.

I think that for most computer owners, the word “modding” no longer raises questions. Modding is for a computer geek what tuning is for a car driver. Coming from the English modify (modify, change), this concept has grown into a whole direction, with an ever-increasing number of fans. And all thanks to enthusiasts who tried to elevate the boring and nondescript gray boxes that so quickly appeared in our apartments. Moding is plastic surgery for your computer and its peripheral devices. With the help of paint, lighting and some modifications, you can achieve a unique, individual design.

I am not inclined to classify myself as a “modder”, although I visit sites devoted to this topic with great pleasure. In practice, I encountered this completely unexpectedly. But first things first.

Where it all started

It all started with a simple renovation in the kitchen. The TV, which returned to its rightful place after the renovation was completed, ended up right under the ceiling - the fact is that the new refrigerator is twenty centimeters higher than the old one. As a result, watching the morning news with a cup of tea became very difficult. After a week, this began to irritate not only me, but the whole family.

At the family council, it was decided to retire the “old hard worker” and replace him with a new modern liquid crystal “perfection” with further placement of it on the wall. There is nothing easier - go to the nearest consumer electronics store and choose a suitable copy. But the prices for these TVs are very, very impressive. There are, of course, inexpensive models, but they don’t inspire confidence in me. And those that attract attention are in the price range from 17,000 to 32,000 rubles. If you take a closer look at the technical characteristics of televisions in this group, there are almost no differences between the matrices of LCD monitors and the matrices of LCD TVs. And often with the same screen resolution (1024x768), they are inferior to them in brightness, contrast and viewing angles. So what's stopping us from combining an inexpensive LCD monitor with an external TV tuner? It’s decided, we’ll assemble the TV with our own hands.

Selection criteria

Here we need to clearly understand what we want to get in the end, and, based on this, draw up a certain list of conditions by which we will select applicants.

We can immediately divide our conditional list into two groups. Group “A” will include mandatory requirements; failure to fulfill at least one will result in rejection of the applicant. In group “B” there will be desirable ones - those that we can, if necessary, compensate on our own. All this, of course, is subjective, and what I have identified for myself may not coincide with the conditions of others.

Monitor (from 9000 to 10500 rub.)

Group A requirements

1. Appearance or design - it’s up to anyone. But if we want to get a TV, and not the feeling of a monitor operating in “screen saver” mode, then we should pay special attention to this point.
2. Viewing angles. A very important parameter, and we are interested in both horizontal and vertical viewing angles. The higher these values, the more comfortable the viewing experience.
3. Brightness and contrast reserve. This parameter, like the previous one, will allow you to achieve satisfactory image quality.
4. Illumination uniformity. Screen illumination is not always uniform. In many inexpensive models, the lower part of the screen is noticeably brighter, especially on uniformly dark images. The better this is implemented, the more evenly the light is distributed. The most common backlight is bottom lighting, when the lamp illuminating the matrix is ​​located at the bottom. Another implementation is possible, but it is more relevant to more expensive monitors or widescreen screens.

Group B requirements

1. Built-in sound system. If you are satisfied with the quality of the sound reproduced by the built-in speakers of the monitor, then the problem of implementing sound for the TV will be solved. Otherwise, in the future you will have to choose an additional sound system, and also look for an additional outlet for it. Powering our TV from three outlets is too much, although this can be easily bypassed if desired.
2. Built-in power supply. The external unit will have to be hidden somewhere.
3. Monitor stand. Ease of dismantling and non-violation of the design features of the monitor will allow you to maintain the warranty on the device. There are stands that allow you to mount the monitor on the wall. It is also advisable to avoid stands with connectors located on them. But all this is subjective, and everyone will choose what they are looking for.

It is advisable to check all these parameters at a stand, and when purchasing, do not really trust the manufacturer’s technical characteristics - sometimes they are disingenuous.

TV tuner (from 2000 to 3000 rubles)

Group A requirements

1. Confident, high-quality reception. The resolution of a conventional TV is slightly lower than the resolution of an LCD monitor, and the more noticeable will be the interference associated with a bad antenna cable, unsatisfactory wiring on the panel and uncertain signal reception. If you can try to solve the first two components on your own, then the latter can only be solved by replacing the device.
2. Fine tuning. Ability to adjust the channel after automatic tuning.
3. Broadcasting system. You need a tuner that automatically adjusts to the broadcast system of the selected television channel, or with the ability to set these values ​​for each channel separately. In accordance with the existing standard in Russia, broadcasting is carried out in the SECAM system, but some regional cable channels use a different encoding for generating color signals.
4. Remote control operation. A convenient remote control and the ability to switch from channel to channel with one click of a button, that is, so that when switching to channels from one to nine you don’t have to dial zero at the beginning, and then 1, 2, 3 ... 9. It’s not difficult, but believe me, it’s inconvenient .
5. Menu. The more convenient the menu is, the more settings that allow you to make corrections after auto scanning, the easier it is to achieve high-quality picture and sound.

Group B requirements

1. Russified menu and documentation. Of course, this is an optional requirement, but it allows you to more comfortably navigate the menu and study the documentation.
2. Channel preview function. It is very convenient, without flipping through channel by channel, but by looking at the preview window and selecting what you are looking for. As a rule, 9-12 channels are displayed on the screen.
3. Return function. Conveniently switch between two channels by pressing just one button. Almost every TV has this feature, and I’m sure many have gotten used to it.

I deliberately do not give specific numerical values ​​for various characteristics, since a discussion on this issue would be inevitable. In addition, for some this may become an unnecessary limitation when choosing devices.

After a short but productive search and comparison, two devices were selected that met my needs. This is BenQ FP591 LCD monitor and GOTVIEW TV tuner - BOX.

In my opinion, BenQ's designers did a great job - I'm sure no one will remain indifferent when they see this monitor. Plus very decent sound with the SRS function and a built-in card reader. As for the tuner, it is also very good. The model, originally designed for the Russian market, has very good reception and a convenient settings menu in Russian.

Assembly

Having everything we need in hand, we begin to implement our plans.

The first thing we need to do is check how well all the devices perform their functions. Only after we make sure that our tandem is working can we begin the main part of the work.

The monitor stand is secured with four screws, which will come in handy later. We unscrew the stand and select a place to mount our LCD panel on the wall. The optimal mounting height, taking into account vertical viewing angles, is approximately 1.5-1.6 m from the floor. We outline the contours of the panel, and also mark the depth of the “pocket” where all the connectors will be located. The two top screws that held our panel on the stand will now hold it on the wall, which means we also mark these places with a pencil. Loops for fastening can either be purchased or made using part of the stand for this purpose (I will not dwell on this, since there is nothing complicated at all).

Next, we estimate and mark the place where we will place the tuner. You need to approach this issue creatively and choose a convenient location for the wires from the tuner connectors. I positioned the device so that the connectors faced to the left - for me it was convenient, although not entirely rational. Considering that the top cover of the tuner will be removed, we make a recess in the wall, approximately 30-35 mm. If the wall is concrete, then you can’t do without a hammer drill. It was somewhat simpler for me - the air duct box is made of plaster, and it lends itself well to a simple chisel (taking this into account, the forces had to be controlled so as not to fall a hole into the shaft).

Next, we carry out preliminary assembly to mark the places where we will hide our numerous wires. Then we make a groove and put everything back in its place, but this time with the laying of the wires.

Next is the most inconvenient, but important moment. Since all the wires will subsequently be closed, and we will not have the opportunity to change their length, we measure as accurately as possible the length of the remaining uncovered wires that will connect the tuner to the monitor. We assemble the entire system and note the length that allowed us to later assemble everything together without interference.

Considering that in the future the visible area of ​​the tuner and the wires will be covered with a layer of mortar and wallpaper, it is necessary to resolve the issue of ventilation and push-button control of the TV tuner.

The issue of ventilation is easily resolved. One option could be a small oblong hole in the air duct shaft, which can be covered with fiberglass or metal mesh. That's exactly what I did.

Push-button control of the tuner was implemented as follows. Wires were soldered to the buttons on the device, as well as to the IR receiver and a diode signaling the operation of the device; a regular IDE cable was used for this. Duplicator buttons were placed on the monitor stand, which in turn was a decorative panel covering part of the tuner.

The panel is attached in the same way as the monitor - using two standard screws on the edges of the stand, which in turn use hinges made from a regular tin can.

Also on the panel were placed: an LED indicator and an IR receiver. To make it easier to dismantle the panel, I connected the wires from the tuner and panel via a standard IDE connector.

The upper part of the buttons was made of colored diodes from the old hub. In my opinion, it turned out very attractive. But I didn’t backlight these very buttons - the abundance of glowing diodes does not give me pleasant feelings. Very reminiscent of a server rack, although this is a matter of taste. You can duplicate and display all the tuner connectors on the panel. It all depends on whether you want to use them in the future or not.

Conclusion

As a result, after finishing the painting and plastering work, wallpapering and final installation, we get an excellent multifunctional TV, of very decent quality, at a price of 12,500 rubles. Plus a bonus for our efforts in the form of a built-in card reader.

The bonus, although exotic, is very useful. Whatever you say, it’s nice, sitting at a good table, in the circle of friends or family, to show on the screen photographs of a recent trip to the sea or to the World Cup. What exactly to show is up to everyone to decide for themselves.

The goal of this project is to create a solar backlit display that can be mounted on your window.
By creating a device, you will get an energy-efficient display without backlight and inverter.
It's nice to look out the window overlooking your garden and see the time, current weather and weather forecast in the left corner of the window.

For this project we will need:

Old computer LCD monitor (see next step);
A Windows-based laptop, laptop, or personal computer (or in my case, a simple client that connects to a virtual machine on the server for improved energy efficiency);
VGA cable of sufficient length;
Gluing gun;
Optional: transparent glue cartridges that require heating.

Step 1: LCD Panel Requirements

There are some requirements for choosing an LCD panel.
As shown in the image above, the top images are the LCD panel without the ribbon cable running behind it.
Some panels, which are shown in the image below, have a ribbon cable that runs from the input PCB (top board) to the output PCB (PCB on the side of the panel). These panels CANNOT BE USED in this project as the cable will be visible and noticeable when illuminated by sunlight. Only panels with two separate boards will work (top image).

Step 2: Disassemble the monitor

At this step you need to completely disassemble the monitor.
Almost everything needs to be taken out.

Here is a list of components that need to be left:
LCD panel (tinted glass like a panel with a printed circuit board attached to it);
Control board (if you can remove the board with the inverter, then remove it);
Flat cable between control board and LCD panel.
!!!BE EXTREMELY CAREFUL WHEN HANDLING THE LCD PANEL, IT IS VERY FRAGILE!!!
!!!THE FLAT PANEL CABLE CAN EASILY BE BREAKED!!!

Step 3: Attaching to the Window

To attach the LCD panel to the window, use glue that requires heating.
This glue will provide excellent and reliable fastening of the panel to the window.

I attached my panel on September 1, 2015, and now it is January 18, 2016. It has now been four months without any work being done to reattach or adjust the position of the panel.

Step 4: Attaching the LCD Control Board

The control board is also attached to the ceiling with glue.
It adheres perfectly to the wallpaper and does not come off over time.

Step 5: Cable Routing

Route the cables from the control board to the computer.
It is necessary to extend the power cable of the control board.
You can cut the power cable and take a longer piece of cable, then strip it and solder them together.

Step 6: Software

This project requires:
Google Chrome browser https://www.google.com/chrome/browser/desktop
Currently (chrome extension) https://chrome.google.com/webstore/detail/currentl…
Auto Refresh (chrome extension) https://chrome.google.com/webstore/detail/auto-ref…

First install the chrome browser.
Then install the extensions according to the footnotes listed above.
Typically, if you close and reopen the chrome browser, you will see the Currently page (current time and weather readings).
If not, then open a new tab.

Then configure the Currently page by clicking the three bars in the upper left corner.
It is recommended to use light colors for maximum visibility and set the zoom level to “zoomed in” for better readability.
Set the page to automatically refresh every 15 minutes (the usual interval for weather updates).

Job done, brainiacs!
Now you can enjoy the display in your window :).

Step 7: Known Issue

If the panel is attached for a long period of time, bugs may appear between it and the window. Perhaps the reason for their appearance lies in the small amount of heat emitted by the panel. If the bugs start to irritate you, then remove the panel using a hair dryer or heat gun on the lowest setting, clean it, and then put the panel back.
In the end, the bugs are not visible at a distance of one and a half meters from the panel.

Step 8: Final Result

This video demonstrates the operation of the device on the first day after installation.

Good luck with your new brain projects!

In order to repair an LCD monitor with your own hands, you must first understand what main electronic components and blocks this device consists of and what each element of the electronic circuit is responsible for. Beginning radio mechanics at the beginning of their practice believe that success in repairing any device lies in the availability of a circuit diagram of a specific device. But in fact, this is a misconception and a circuit diagram is not always needed.

So, let’s open the cover of the first LCD monitor that comes to hand and in practice we will understand its structure.

LCD monitor. Main functional blocks.

The LCD monitor consists of several functional blocks, namely:

LCD panel

The liquid crystal panel is a complete device. As a rule, the assembly of an LCD panel is carried out by a specific manufacturer, who, in addition to the liquid crystal matrix itself, embeds into the LCD panel fluorescent backlight lamps, frosted glass, polarizing color filters and an electronic decoder board that generates voltages from digital RGB signals to control the gates of thin-film transistors (TFTs). ).

Consider the composition of the LCD panel of a computer monitor ACER AL1716. The LCD panel is a complete functional device and, as a rule, there is no need to disassemble it during repairs, with the exception of replacing failed backlight lamps.

LCD panel marking: CHUNGHWA CLAA170EA

On the back of the LCD panel there is a fairly large printed circuit board, to which a multi-pin cable is connected from the main control board. The printed circuit board itself is hidden under a metal strip.

LCD panel of Acer AL1716 computer monitor

The printed circuit board contains a multi-pin NT7168F-00010 chip. This microcircuit is connected to the TFT matrix and participates in the formation of the image on the display. From the NT7168F-00010 microcircuit there are many pins, which are formed into ten loops under the designation S1-S10. These cables are quite thin and appear to be glued to the printed circuit board on which the NT7168F chip is located.

LCD panel printed circuit board and its elements

Control board

The control board is also called the main board ( Main board). The main board houses two microprocessors. One of them is a control 8-bit microcontroller SM5964 with an 8052 core and 64 kB of programmable Flash memory.

The SM5964 microprocessor performs a fairly small number of functions. A button panel and monitor operation indicator are connected to it. This processor controls turning the monitor on/off and starting the backlight inverter. To save user settings, a memory chip is connected to the microcontroller via the I 2 C bus. Typically, these are eight-pin non-volatile memory chips of the series 24LCxx.

Main board of LCD monitor

The second microprocessor on the control board is the so-called monitor scaler (LCD controller) TSU16AK. This microcircuit has many tasks. It performs most of the functions related to converting and processing the analog video signal and preparing it for submission to the LCD panel.

With regard to an LCD monitor, you need to understand that it is inherently a digital device in which all control of the pixels of the LCD display occurs digitally. The signal coming from the computer's video card is analog and for its correct display on the LCD matrix it is necessary to carry out many transformations. This is what a graphics controller is designed for, or otherwise a monitor scaler or an LCD controller.

The tasks of the LCD controller include such as recalculation (scaling) of images for different resolutions, formation of the OSD menu, processing of analog RGB signals and sync pulses. In the controller, analog RGB signals are converted to digital via 3-channel 8-bit ADCs that operate at 80 MHz.

The TSU16AK monitor scaler interacts with the SM5964 microcontroller via a digital bus. To operate the LCD panel, the graphics controller generates synchronization signals, clock frequency and matrix initialization signals.

The TSU16AK microcontroller is connected via a cable to the NT7168F-00010 chip on the LCD panel board.

If the graphics controller of the monitor malfunctions, as a rule, defects appear related to the correct display of the image on the display (stripes may appear on the screen, etc.). In some cases, the defect can be eliminated by soldering the scaler leads. This is especially true for monitors that operate around the clock in harsh conditions.

During prolonged operation, heating occurs, which has a bad effect on the quality of soldering. This may cause malfunctions. Defects related to the quality of soldering are not uncommon and are also found in other devices, for example, DVD players. The cause of the malfunction is degradation or poor-quality soldering of multi-pin planar microcircuits.

Power supply and backlight inverter

The most interesting thing to study is the monitor's power supply, since the purpose of the elements and circuitry are easier to understand. In addition, according to statistics, malfunctions of power supplies, especially switching ones, occupy a leading position among all others. Therefore, practical knowledge of the device, element base and circuitry of power supplies will certainly be useful in the practice of repairing radio equipment.

The LCD monitor power supply consists of two. The first one is AC/DC adapter or in other words, a network switching power supply (pulse unit). Second - DC/AC inverter . Essentially these are two converters. The AC/DC adapter is used to convert 220 V AC voltage into a small DC voltage. Typically, voltages from 3.3 to 12 volts are generated at the output of a switching power supply.

The DC/AC inverter, on the contrary, converts direct voltage (DC) into alternating voltage (AC) with a value of about 600 - 700 V and a frequency of about 50 kHz. Alternating voltage is supplied to the electrodes of fluorescent lamps built into the LCD panel.

First, let's look at the AC/DC adapter. Most switching power supplies are built on the basis of specialized controller microcircuits (with the exception of cheap mobile chargers, for example).

In the documentation for the TOP245Y chip you can find typical examples of circuit diagrams of power supplies. This can be used when repairing power supplies for LCD monitors, since the circuits largely correspond to the standard ones indicated in the description of the microcircuit.

Here are some examples of circuit diagrams of power supplies based on TOP242-249 series microcircuits.

Fig 1. Example of a power supply circuit diagram

The following circuit uses dual Schottky barrier diodes (MBR20100). Similar diode assemblies (SRF5-04) are used in the Acer AL1716 monitor unit we are considering.

Fig 2. Schematic diagram of a power supply based on a microcircuit from the TOP242-249 series

Note that the above circuit diagrams are examples. Actual circuits of pulse blocks may differ slightly.

The TOP245Y microcircuit is a complete functional device, the housing of which contains a PWM controller and a powerful field-effect transistor, which switches with a huge frequency from tens to hundreds of kilohertz. Hence the name - switching power supply.

LCD monitor power supply (AC/DC adapter)

The operating diagram of a switching power supply is as follows:

Rectification of alternating mains voltage 220V.

This operation is performed by a diode bridge and a filter capacitor. After rectification, the voltage across the capacitor is slightly higher than the mains voltage. The photo shows a diode bridge, and next to it is a filtering electrolytic capacitor (82 µF 450 V) - a blue barrel.

Voltage conversion and reduction using a transformer.

Switching with a frequency of several tens to hundreds of kilohertz of direct voltage (>220 V) through the winding of a high-frequency pulse transformer. This operation is performed by the TOP245Y chip. A pulse transformer performs the same role as a transformer in conventional network adapters, with one exception. It operates at higher frequencies, many times higher than 50 hertz.

Therefore, the manufacture of its windings requires a smaller number of turns, and, consequently, less copper. But a core of ferrite is required, and not of transformer steel as in 50 hertz transformers. Those who do not know what a transformer is and why it is used, first read the article about the transformer.

The result is a very compact transformer. It is also worth noting that switching power supplies are very economical and have high efficiency.

Rectification of alternating voltage reduced by a transformer.

This function is performed by powerful rectifier diodes. In this case, diode assemblies labeled SRF5-04 are used.

To rectify high-frequency currents, Schottky diodes and conventional power diodes with p-n junctions are used. Conventional low-frequency diodes for rectifying high-frequency currents are less preferable, but are used for rectifying high voltages (20 - 50 volts). This must be taken into account when replacing defective diodes.

Schottky diodes have some features that you need to know. Firstly, these diodes have a low junction capacitance and are able to quickly switch - go from open to closed state. This property is used to operate at high frequencies. Schottky diodes have a low voltage drop of about 0.2-0.4 volts, versus 0.6 - 0.7 volts for conventional diodes. This property increases their efficiency.

Schottky barrier diodes also have undesirable properties that hinder their wider use in electronics. They are very sensitive to excess reverse voltage. If the reverse voltage is exceeded, the Schottky diode irreversibly fails.

A conventional diode goes into reversible breakdown mode and can recover after exceeding the permissible reverse voltage value. It is this circumstance that is the Achilles heel, which causes the burnout of Schottky diodes in the rectifier circuits of all kinds of switching power supplies. This should be taken into account when carrying out diagnostics and repairs.

To eliminate voltage surges that are dangerous for Schottky diodes and are formed in the transformer windings at the pulse fronts, so-called damping circuits are used. In the diagram it is designated as R15C14 (see Fig. 1).

When analyzing the circuitry of the Acer AL1716 LCD monitor power supply, damping circuits were also found on the printed circuit board, consisting of a 10 Ohm SMD resistor (R802, R806) and a capacitor (C802, C811). They protect Schottky diodes (D803, D805).

Damping circuits on the power supply board

It is also worth noting that Schottky diodes are used in low-voltage circuits with a reverse voltage limited to a few tens of volts. Therefore, if a voltage of several tens of volts (20-50) is required, then diodes based on p-n junctions are used. This can be seen if you look at the datasheet for the TOP245 chip, which shows several typical power supply circuits with different output voltages (3.3 V; 5 V; 12 V; 19 V; 48 V).

Schottky diodes are sensitive to overheating. In this regard, they are usually installed on an aluminum radiator to dissipate heat.

You can distinguish a diode based on a pn junction from a diode based on a Schottky barrier by the conventional graphic designation in the diagram.

Symbol for a diode with a Schottky barrier.

After the rectifier diodes, electrolytic capacitors are installed to smooth out voltage ripples. Next, using the resulting voltages 12 V; 5 V; 3.3 V powers all LCD monitor units.

DC/AC inverter

In terms of its purpose, the inverter is similar to electronic ballasts (EPGs), which are widely used in lighting technology for powering household fluorescent lighting lamps. But, there are significant differences between the electronic ballast and the LCD monitor inverter.

The LCD monitor inverter is usually built on a specialized chip, which expands the range of functions and increases reliability. For example, the backlight inverter of the Acer AL1716 LCD monitor is built on the basis of a PWM controller OZ9910G. The controller chip is mounted on a printed circuit board using planar mounting.

The inverter converts direct voltage, the value of which is 12 volts (depending on the circuit design), into alternating voltage of 600-700 volts and a frequency of 50 kHz.

The inverter controller is capable of changing the brightness of fluorescent lamps. Signals for changing the brightness of the lamps come from the LCD controller. Field-effect transistors or their assemblies are connected to the controller microcircuit. In this case, two assemblies of complementary field-effect transistors are connected to the OZ9910G controller AP4501SD(Only 4501S is indicated on the chip body).

Assembly of field-effect transistors AP4501SD and its pinout

Also, two high-frequency transformers are installed on the power supply board, which serve to increase the alternating voltage and supply it to the electrodes of the fluorescent lamps. In addition to the main elements, the board contains all kinds of radio elements that serve to protect against short circuits and lamp malfunctions.

Information on repairing LCD monitors can be found in specialized repair magazines. For example, in the magazine “Repair and Service of Electronic Equipment” No. 1, 2005 (pp. 35 – 40), the device and circuit diagram of the LCD monitor “Rover Scan Optima 153” are discussed in detail.

Among monitor malfunctions, there are quite often those that can be easily fixed with your own hands in a few minutes. For example, the already mentioned Acer AL1716 LCD monitor came to the repair table due to a broken contact of the socket outlet for connecting the power cord. As a result, the monitor turned off spontaneously.

After disassembling the LCD monitor, it was discovered that a powerful spark was formed at the site of the poor contact, traces of which were easy to detect on the printed circuit board of the power supply. A powerful spark was also formed because at the moment of contact the electrolytic capacitor in the rectifier filter is charged. The cause of the malfunction is solder degradation.

Solder degradation causing monitor failure

It is also worth noting that sometimes the cause of the malfunction can be a breakdown of the diodes of the rectifier diode bridge.