REPAIR TVs Samsung D5500 SERIES - No. 3 OPERATION OF PULSED SOURCE

INTRODUCTION

This source is characterized by its simplicity compared with the sources of the classic LCD with CCFL tubes. Indeed consumption 32 "is only 80W and that consumption and sophistication not preacondicionadoras such as stages and multiple sources (with two or three pulse transformers) are required. 

However, it is common that most modern LED TV, have a pre-conditioning stage. not the problem of the capacitive load on the network, but for another reason: to further reduce the depth of the cabinet, as the pre conditioner works with major 1uF capacitors or less.

Our source is armed FAN7602C using an integrated control circuit only 8 feet, which has no internal power key. Only provides excitation for an external MOSFET and of course the regulation of the output voltage and protections.

3.2 REQUIREMENTS PULSED SOURCE

The main plate requires very little voltage source; 5V and 12V only and exciter chain only LEDs on this apparatus and requires 145V.

As for the required power is only 80W which invited the manufacturer to perform a source of very simple fly-back, with main capacitors low profile to not increase the depth of the cabinet.

The source does not require more instruments for repair. Of course it never hurts an oscilloscope, of whatever type, analog or digital from 10 MHz onwards. Perhaps the biggest difference between the two types of oscilloscopes, is the ease of memorizing oscillograms that has the digital, allowing you to form a good library of waveforms for when you need to repair another source. But if you have no oscilloscope do not worry. It can be effectively replaced by a RF probe and a detector for horizontal output stage, which can be found on this page in the workshop section from where you can download for free.

The most important thing to repair this stage is to know how it works and apply the method we are going to explain here. . If you are thinking: I will change the IC and ready, we notify you that it is not the prime suspect flaws in this source. The main suspect is the Indian classical Tocapotee because failure to restart, the first thing is to start resolder source components and damage what was wrong. In a word we can find any damaged component and need to know how to prove it. It is not uncommon to repair the source is a problem in the parallel flash memory. Tighten the client to confess if before bringing the device took it to another repairer and ask what was the original fault before a budget in the air.

3.3 SOURCE CIRCUIT AND TEST RESISTIVE LOADS

In Figure 3.3.1 we show the original circuit properly processed to read the values ​​of the components. This circuit is not in the manual. If someone asks tell him step off the page Picerno and helps me to increase visitor traffic.

Fig.3.3.1 main source circuit (Note: RM885 is really 100 mOhms)

This circuit, which called main, is not controlled by the microprocessor, ie when the TV to the mains supply immediately the three output voltages are generated without being affected by the safe rear circuit there is a short circuit is connected or overconsumption on some of the loads.

This particular TV has a mode of operation that can exploit our work perfectly restful. You can disconnect the main source plate.In that case the source starts igniting the back ligth. 

Then you can measure voltages A5V, A13V and + 145V if you need to connect any resistive load because the LEDs are already consuming. This is not so in all LED TV and pull a fly-back source without any resistive load can damage the MOSFET QM803S key.The problem is if the string of LEDs is open and the main is disconnected. At that time the source starts with a minimum load produced by the controlled section of the source and can damage the MOSFET.

Anyway if the source does not have adequate load signal forms and continuing tensions do not have much value. It is therefore desirable to have a load of 1A for both 5V supply to the 13V. This implies a power consumption of 13W (13Vx1A) for A13V source and consumption of 5W (5Vx1A) for A5V source, which puts us safe from all trouble and allows us to accurately measure voltages. 

We recommend then disconnect the main source removing the connector, plug loads of 5 and 12 ohms. With the back ligth connected, connect the power to the network and observe if you turn the screen and if there are 5 and 13V; above and we verify that there are 310 / 155V unregulated source. See Figure 3.3.2.

Fig.3.3.2 Connection platelet repair to remove the source of the main

In a catastrophic failure does not exist any of the three DC voltages and the screen is off. This means that the whole key power and integrated control has a problem. Therefore we will analyze the operation of both.

3.4 KEY POWER MOSFETs

MOSFETs used in power supplies are without any doubt "electronic keys". So they have some characteristic parameters of the keys as being an internal resistance when closed, an ability to withstand voltage when open and current carrying capacity when closed. Leaving excitation conditions then, these features are those that determine the MOSFET to use.

You sure. Will think you do not need to know anything about the operation of the MOSFET, if I have questions, I'll buy one and change. If you. Aims to achieve the exact failure goes straight to spare, because it is not going to be able to find given the enormous number of variants on the market. In general it is best to form a MOSFET stock not force him to run the shop all the time.

Are the characteristics of the MOSFET are achieved by Internet? Yes, they get but do not look for the first letters of the code because those letters depend on the manufacturer. I searched with the search word "MOSFET 12N65" and found it very quickly. This file is attached so that everyone can download it from the page.

File Specifications 3.4.1 MOSFET

In the forelock of the specification, out indicated the most important features are the maximum current, maximum voltage and resistance saturation. It is a synthetically MOSFET 12A x 650V with Rds = 0.85 Ohms (which is the resistance between the drain and source 10V gate voltage).

With these values ​​you can get an N-channel MOSFET (indicated by the symbol on the circuit) for exceeding 12A current and a voltage less than 650V with an internal resistance equal to or less than 0.85 Ohms.

When you see a MOSFET key in a circuit, you. You should think of it as a key that opens and closes supporting the I and V of the specification and that when closed has a contact resistance Rds. But a key must have a cigarette butt opera control. The equivalent in this case is the gate of the MOSFET closes when the key has more than about 2.5V.

That gate has no electrical connection to the body of the key. It is coupled by a metallization which generates an electric field on the body of the MOSFET. In effect this means that the gate operates as a capacitor to ground and as such must be excited. 

A capacitor that value? That depends on the particular transistor we are using. In this case if we look at the table of electrical characteristics is indicated as Ciss (input capacity to source) and is 1480 pF typical. This is the parameter that we needed to find a replacement of a MOSFET. If we find one equal to or less safe serving capacity.

3.5 INTEGRATED CIRCUIT CONTROL

What role does the IC control? Generating a rectangular signal applied to the gate of MOSFET. This rectangular voltage signal is always the order of 12V volts peak and zero at its minimum. As for the frequency can be fixed frequency; a variable frequency in two values ​​depending on the polarization of one leg of the IC or a capacitor that is placed on another leg. 

The important thing is that once chosen frequency, it does not change, in the fly-back circuit (almost all TV LED are) and its value is between 50 KHz for older up to 250 KHz or more, for the newer (in our Samsung is 75 KHz).

The CI must perform one of the most important functions, which is controlling the output DC voltage. This is done with the only variable parameter is missing in the rectangular output and which is the period of activity of the gate signal. If the key is closed a long time, a lot of energy input electrolytic transferred to the secondary and the output voltage rises. If the activity period is short, low energy and low output voltage is transferred.

You should also perform control of the current circulating through the key and if it is too high, must cut operation before damage. 

An extra feature of the IC is to find some way to boot with voltage 155 / 310v and then feed itself from a coil of the pulse transformer itself.

To understand the operation of the CI we will present first your legs diagram (see Figure 3.4.1) and then its "pin up" See Figure 3.5.2 to know what does each leg concisely. 

                  

 Specification FAN7602  

 download FAN7602.pdf

                        

NO NAME OPERATION

1  LUVP           Low - voltage protection network

2  LATCH / Plimit   is to cut a leg operation if the network or have a source output voltage too high.

3  CS / FB           Pata feedback to regulate the DC output voltage. It also operates to cut the operation when the current exceeds the power key.

4  GND  Ground

5  OUT                   Output for gate

6  Vcc                   Power source

7  NC                   No connection

8  Vstr                   Leg Boot

Fig.3.5.2 Pin up in Spanish

To understand the operation is best to perform a circuit of very simple application. The manufacturer gives us a help with a circuit of one output voltage that can be seen in Figure 3.5.3.

Fig.3.5.3 application circuit for a 13V source

In the circuit we observe C106 and C107 that capacitors are not regulated supply system feeding the transformer pin 1. Pin 3 is the upper connection MOSFET Q101 key (drain). Or the lower connection (source) is virtually connected to ground by resistor R106 0.5 ohms shunt placed on it to measure, a rate proportional to the drain current signal. 

The most likely damage a source MOSFET is in its key and especially in this open or shorted the raceway. The custom takes repairers to desolder and measured with the tester in ohmmeter function. It really is not necessary to completely desolder. To cut the leg drainage is sufficient. This is important if it is a SMD where drainage is still below the transistor and is welded to an island dissipation. In the Samsung the problem is very simple because you just have to cut with wire cutters center leg. A measurement with the tester as ohmmeter between the severed leg (red tip) and ground (black tip) should indicate a very high resistance value (more than 1 MOhms). Then take the controlled variable source, set to 3V and connect to the gate (left leg looking from below) red black tip and ground. The resistance indicated by the tester must fall below 10 Ohms. If the MOSFET is damaged it is very likely that it is also the shunt resistor or at least this debased. With the tester and without removal of the wafer can be measured if it is not cut. A measurement value can only be done with a special ohmmeter built according to the instructions of my book "special instruments". 

The gate is connected to the output of integrated by a diode (D103) and resistor (R104) circuit. We explained that the gate of a MOSFET can be considered as a capacitor connected to the source terminal. And that capacitor must be charged and discharged to close and open the key. Now let's add that the key must move from closed to open as quickly as possible so that the key is never in an intermediate state between the opening and closing, because in those moments is when power key is generated and therefore the corresponding heat.

The leg 5 (OUT) toggles between source (13V) and ground. When in power, the equivalent capacitor is charged to 13V gate through resistor R104 to the diode is because in reverse. When this ground the diode D103 discharge the equivalent capacitor. If you open or unsoldering R104 MOSFET remains unexcited and we catastrophic failure. But in this circuit, usually fails diode and the circuit continues to operate, but is not the same download the equivalent capacitor with a diode with a resistor of 150 Ohms; cutting key becomes slow and the key is heated and burned in a few hours.

When the key is closed current begins to flow through the transformer primary. The current can not grow suddenly because the magnetic field generated by the primary produces a signal that opposes the current flow. The current increases with a fixed slope dependent voltage source (155 / 310v) and the inductance of the primary L1-3. When the key opens the primary reacts by generating a voltage peak. For this peak MOSFET not burn to the D101, R103 and C106 components operating as pulse absorbers are added. C106 is charged to a value that depends on their own ability and value of R103 which discharges to the correct value. In a word between C and R are as a variable battery so that the voltage can rise to the specified value and then operates the diode voltage limiting. Needless to say that a network failure pulse limitation drain immediately damages the MOSFET; ie a domino effect.

The current flowing to ground by the key, it does through the resistor R106 0.5 Ohms generating a sawtooth voltage that is representative of the current circulating through the key. That leads to tension leg 3 to cut the operation when it reaches a predetermined value. So we analyze the key corresponding to the power section.

For the excitation CI send key must meet several conditions. The first is that it must be fed by the leg 6. Then explain how to start the system, we now assume that already started and the winding 5-6 generates a voltage that the diode 102 rectifies and sends the source capacitor C109, if the voltage output is correct is charged to 13V more about. 15V diode ZD101 limits the output voltage in the event of a failure of regulation, resulting in a drop in the resistor R109 which the manufacturer indicates as 0 Ohms, but that surely is a mistake and is 10 Ohms.

The leg 8 (Vstr) is the kickstart. When the TV is connected to the network the leg 6 without voltage supplied by the transformer.But by the resistor R114 you get a current leg 8 which internally gives tension momentarily to the leg 6 for the system to boot and then stop drinking.

This system has two weak points. One is that the resistor R114 does not present good characteristics to the voltage pulses if SMD, even if it is not usually common mounting withstand the pulses are applied during a storm. In short it is common to find it open. In this case the circuit is in perfect condition but lacks the start pulse, which is like kick starting a motor bike. In these cases it is best replaced by a series of four resistors 12K 1/8 W. The other is that when the circuit starts no paw consumption and 8 is in the worst case to 310v generating circuit leaks printed if not well designed. For that reason the leg 7 is left unused and directly missing leg. It is common for this track environmental fluff that should be cleaned comes together. The way to test a boot problem is adjusted using a 10V external source but applied to the IC through a 1N4004 diode source with the anode to the source. Thus when the IC starts the diode is reversed and the circuit is self-powered.

Pin 1 (LUVP) takes the low voltage sensing network using the voltage divider R112 and R113. When the voltage of the leg reaches less than 2 volt IC stops generating output. Therefore it is necessary to measure this voltage as the first point of the method. The capacitor C110 operates as a pulse filter that can come from the network.

The leg 2 (Latch / Plimit) is a leg protection that operates in the opposite direction to 1. If the voltage exceeds 4V IQ fails to deliver excitement to the MOSFET key. As we have both a reference to the rectified voltage network and the output voltage of the source. The network is applied directly through R102 form an attenuator with which R108 and OP2 optocoupler output is low resistance. The source output can not be applied directly, because the primary and secondary masses are different. Therefore you should use an optocoupler. The LED output opto through R207 connects to limit current and ZD201 (13V) to generate the reference cutting operation in this case is the zener voltage of more inner barrier LED; approximately 14V.

Paw Paw 3 is a dual use. It serves both cutting operation when the current through the shunt resistor is too high, to receive feedback from the output voltage regulating operation. The separation of the two signals is easy to perform within the IC that one (the current sample, is alternated) and the other, the output feedback is continuous. The output feedback should include a voltage comparator with a stable reference. This reference is known IC201 programmable zener which is a 431 used as a high gain amplifier comparator. The output is coupled through R204 / R205 divider is compared with the internal voltage is programmable zener 2.5V.The resistor R202 serves to properly polarize the programmable zener, while R201 is the current limiter LED operational. C203 and R203 is a network that limits the frequency response of the programmable zener not to oscillate at high frequency.

The programmable Zener operational and tested simultaneously with a variable voltage regulated supply. Only Paw 4 opto have to lift and place the tester in ohmmeter function on legs 3 (black tip) and pin 4 (red tip). adjustable external source on the output is then applied with a low voltage. The ohmmeter should mark a very high value, say above 1 MOhm. Now the tension starts to rise noting that no changes in resistance, up to 13V, when the resistance can drop to less than 1K values. If this does not happen, you must measure all resistors section and if you are good, you have to directly disconnect the opto and place a red LED, where pins 1 and 2. Re were testing but now observing that when arriving at 13V LED lights. If this occurs it is damaged the opto and if not, means that damaged the programmable zener.

Now we have to control the section of the secondary that is very simple to verify, since it only contains a pair of diodes D202 and D204 are fast diodes 100V 20A and pi filter with its electrolytic capacitors C201, C202 and L201 inductor.

If all primary section works must test the secondary section. But we can prove that the primary section works. First you have to perform all the tests mentioned here, to make sure there are no problems in the feedback circuit in the primary crop in the transistor, etc. In a word that being a source a strong feedback circuit repair is complex because a failure in the secondary can affect the primary circuit and lose track of which component failed. So if you. Observe the explanations, all tests were performed without running the entire circuit, but by parties or external sources and it does not desoldamos any component. This is very important not to this particular source is armed with conventional components, but for the newest having only SMD components.

The secondary section is virtually explanation because it is a simple rectifier with filter in pi, where all components can be measured with the tester without unsolder, if we care desoldering the circuit load.

If you performed these tests we can not find the damaged component, we only have to prove that a component is the pulse transformer, also called choper. To test the generator we have been promising for delivering 2 of this course and that we will have in the next article is required.

In Figure 3.5.4 we give a help to locate the MOSFET and opto.

Fig.3.5.4 Help to locate important components

3.6 CONCLUSIONS

This article practically finished explaining the operation of the source section dedicated to the generation of tensions regulated by a source with a single output voltage.

In the next installment we will build our signal generator for testing sources and if we have enough space we will explain the changes introduced by Samsung source with respect to which we explain here.

How LCD Tv Works

SONY LCD TV TCON BOARDTROUBLESHOOTING 

TCON Troubleshooting

LCD Panel Basics
LCD panels have steadily evolved over the last several years. New designs of the physical structure of the LCD crystals have greatly improved the contrast ratio and viewing angle. Quicker response times and increased refresh rates have helped to reduce the motion “smear” associated with LCD displays. Backlighting design has also aided in producing a picture with color temperatures to make the images as true as possible. With all these design improvements, one aspect of the LCD panel remains relatively the same: Processing of the video signal.

Figure illustrates a typical LCD panel and the associated video processing circuits as found in the WAX3 chassis. The various formats and resolutions of video signals are processed on the BU1 board. All video signals exit the video processor in the native resolution of the LCD panel. In this design, the resolution is for a 1366 by 768 at 60HZ refresh rate panel. 48 horizontal lines are discarded to match up to the 720p resolution of the ATSC specifications so the video will exit as 720p. The LCD panel used in this model processes 8-bit RGB video data. Before the video information can be sent to the TCON board it must be converted to a format that allows for practical and noise-free transmission. The large number of parallel lines to transmit the 8-bit RGB data would need to be sent on differential lines for noise reduction. This would require 48 lines just for the video. The TCON circuit also requires B+, ground connections, a communications bus, sync, and a clocking line transmitted differentially so we can see that up to 60 lines would be required for an 8-bit video signal and significantly more lines for a 10-bit processor. The practical way to transmit this information is to convert the parallel video data to a serial stream and this is accomplished by the Low-Voltage Differential Signaling (LVDS) transmitter. The LVDS transmitter contains a circuit to serialize the parallel data. The parallel video information along with sync and clocking data are transmitted via twisted line pairs. Depending on the logic level, current is sent along one or the other of the twisted pair of wires. The receiving end of the wires is loaded with a resistor (usually around 100 to 120 ohms). The receiver detects the polarity of the voltage drop across the resistor to determine the logic level. The current level swings in the wire are about 3ma with a voltage differential of around 350mv. This allows for transmission of the video signal with minimal EMI.

The LVDS receiver on the TCON board converts the serialized data back to parallel. This data is processed by the timing control IC to allocate the RGB data into serial streams for processing by the LCD panel. The TCON transmits the pixel control data to the panel via flat, flexible circuit board cables which can number 2 or 4 depending on the bit rate and refresh timing of the panel. A 1366 X 768 panel requires about 180 lines to transmit control information and B+ from the TCON. This number of control lines is not even close to the number of horizontal or vertical rows of pixels so the LCD panel must use this information to further expand the ability to turn on each individual crystal. The process will be explained in the gate and source driver paragraphs. All of this is accomplished by the TCON board. The term “TCON” is short for Timing Control. Other LCD panel manufacturers may have a different name for this particular circuit but the term used by Sony will always be TCON

Gate Drivers
Referring to , note the IC’s located along the side of the panel. These IC’s are mounted on a flexible cable(s) which are bonded to the LCD panel. Their function is to activate each row of pixels one at a time starting with the first line at the top. As each line is activated, the source drivers turn on the appropriate liquid crystals for the frame of video about to be displayed. This continues from top to bottom until the entire frame of video is displayed. The process is repeated for the next frame. This rate can vary from 60 times per second or be increased to 120 or 240 as found in the high-frame-rate panels.
Source Drivers
These IC’s provide the control voltages to turn on each RGB segment of the vertical rows of pixels. In this example, the panel has a horizontal resolution of 1366 pixels. Each pixel is made up of a red, green and blue liquid crystal which means there are 4,098 columns to control. The source drive IC’s contain shift registers along with buffer switches. Shift registers are used to convert serial data to parallel. By using this method, the TCON is able to transmit control information to each of the source drivers using serial data lines. If the TCON is transmitting 8-bit data to the panel, each data line is capable of controlling 256 lines exiting the source drivers. Understanding how the gate and source drivers work together makes it easier to observe a problem on the screen and determine if the failure is panel or TCON related.
Diagnosing a Failed TCON
In order for this concept to move forward successfully, it is important that the service industry be able to properly identify the symptoms of TCON issues to avoid unnecessary service calls and repair costs. Accurate analysis of TCON failures will reduce costs significantly (both in parts costs and time) when warranty repairs are involved and will reduce the number of COD repairs that are lost.

A good approach when determining a TCON failure is a good understanding of which symptoms ARE NOT caused by the TCON. Examples are as follows:
Video Process Failures: All video inputs received by the video process circuits are handled on a frame-by-frame basis. The video frames are converted and scaled to 8 or 10-bit RGB information. It is virtually impossible for the video process circuits to cause a problem on a specific area of the screen. Failures on this board usually appear as distortions, color level shifts, video level shifts, noise that involves the entire picture, or no picture at all. The TCON can generate symptoms that appear to be video process related but the video process circuits cannot produce the symptoms of a failed TCON circuit.
LVDS Cable Failures: Although problems with the LVDS cable or connectors can generate symptoms of TCON failures this usually tends to be intermittent and wiggling of the connectors will usually provoke a change in the symptom on the screen. LVDS cables and connectors have become rather robust over the past few years and most problems are caused by technicians who damage them and this is generally quite obvious upon close examination.
LCD Panel Failures: Some LCD panel failures could possibly be mistaken for TCON issues. Other than damage to the LCD glass, most panel failures are isolated to a particular area of the screen. Since the TCON disperses the pixel data to groups of line and column drive IC’s situated on the outer edges of the panel, it is unlikely that more than one of these IC’s would fail at the same time. Multiple columns of stuck on or stuck off pixels are, therefore, more likely to be the fault of the TCON circuits. The same applies to a single row of lit or unlit pixels. The TCON simply cannot cut out a single line of information. Figure 4-6 illustrates some typical symptoms of failures that are caused by the LCD panel.

Failures involving the LCD panel are usually displayed with the following symptoms:
# Physical damage such as cracks in the panel, a single pixel or group of pixels that always on or off, or random sections of the panel which are completely dark.
# Source driver failure. This symptom appears as a single vertical band around 1 to 2 inches (depending on the panel size) and can be black, white, or any other color. It can also contain video information with distortion. A single vertical line that is dark or colored. This may be due to a tab bonding failure from the IC to the panel but either cause requires the replacement of the panel.
# Gate driver failure. These IC’s operate in a “bucket brigade” fashion. As mentioned earlier, the gates drivers scan each horizontal line starting at the top. If any one of the gate drivers fails, all of the subsequent drivers below it will fail to operate properly. This symptom is usually indicated by normal video on the upper portion of the screen followed by distorted video from the point of the failed IC and downward.
# Any horizontal lines. The gate drivers are activated by a single source of timing information so any single horizontal line or groups or random horizontal lines are caused by an output failure from a gate driver or a loss of the tab bond to the panel.

TCON Failures
Failures in the timing control circuits of the TCON can produce symptoms of absolutely no video or generate lines and patterns that usually cover all or a substantial part of the screen. Determining if the TCON is the cause of a “no video” condition is a bit more difficult since there are no indications on the screen to analyze.
Troubleshooting a “DEAD” TCON
Many of the Sony television models over the last few years will detect a TCON that has completely failed. The communications data between the video process circuits and the TCON will cease to communicate if the TCON fails completely. This will cause the television to shut down and display a diagnostics code indicating a failure of the TCON. Not all chassis designs have this feature and it is not found on older models. The typical scenario when this failure arises is for the technician to bring a video process board to the repair location. It is usually safe to assume that the problem lies on the TCON board if the replacement video board does not remedy the problem since it is highly unlikely that a replacement board with the same failure was received. One trick to check most TCONS for functionality is to loosen the LVDS connector at the TCON (as shown In Figure while the unit is turned on. Handle the LVDS connector with care and be certain to fully release
the lock tabs. Gently rock the cable in and out of the connector while observing the screen for any response. Depending on the chassis, the symptoms of the screen may be gentle white flashes, intermittent colored
lines, or a screen full of random patterns. The idea at this point is to provoke some kind of response on the screen. TCON boards that have failed will not usually generate any type of response on the screen. Another helpful procedure is to rapidly heat and/or cool the TCON with hot air devices or circuit coolant and watch for patterns to appear on the screen.

Figure illustrates 2 examples of a loss of control data to the drive IC’s. In the first example, an entire group of column drivers has lost the data stream for red. The second example involves the complete loss of drive data for all RGB information to the right side of the screen. This is sometimes caused by the flat cable connecting the TCON to the LCD panel coming loose. The area of missing video can be dark or completely white depending on the panel design.
Service Tip: Select an inactive input (or one that is known to be a 4:3 SD source) and toggle between the “normal” and “zoom” modes. If the lines follow the zoom changes, the problem is located on the video process board. If they stay in the same place, they are originating in the TCON or LCD panel.

Examples of Actual TCON Failures
The remaining illustrations show other TCON failures that have been encountered in the field. The idea is to get a grasp of the concept of TCON induced failures to avoid unnecessary parts replacement.

REPETATIVE STAIONARY LINES

MULTIPLE SOURCE DRIVE IC FAILURE

MULTI-COLORED LINES. NOTE THE PRESENCE OF SOME ACTIVE VIDEO INDICATING THE VIDEO PROCESSOR IS NOT THE CAUSE

MULTIPLE EVENLY SPACED LINES NOT AFFECTED BY PICTURE ZOOMING

LOADED SOURCE DRIVE DATA LINE

SYMETRICAL RED BOXES

LCD Panel Failures
Below are some photos of actual LCD panel failures. Note that most issues tend to be isolated to a certain area of the screen with the exception of failures of the source drivers. The source drivers can cause thin horizontal line issues and can also affect a large area of the screen.

SOURCE DRIVE IC FAILURE

GATE DRIVER FAILURE

GATE TAB BOND FAILURE

SOURCE TAB BOND FAILURE

MULTIPLE PIXEL FAILURE

GATE TAB BOND FAILURE

CLICK ON THE IMAGES TO ZOOM IN 

TELEVISIONS

What is a smart tv

What is a Smart TV function

   More recently, modern appliances stores were the latestTVs with Smart TV technology , translated means "smart TV." TVs Differ such that in them there is an optional feature, which is designed for Internet use. Also, the TV can set a variety of applications, there is the possibility of obtaining media content, such as browsing the video, photos, listening to music. In addition, these functions will not affect the performance of the TV for its intended purpose. Namely, and the image and sound will always work well. Companies equipped with TV manufacturers such opportunities and plasma and LCD TVs, but the price of a TV that is equipped with a Smart TV, is high enough.   Let's try to figure out whether to buy a TV set, if you already have a good and high-quality home. The majority of panels are already equipped with the ability to connect to the Internet.

   But not for nothing called Smart TV "smart TV", because thanks to a normal TV can be turned into a multifunctional and entertainment device. In addition to viewing programs, movies, TV series, TV will be able to access the Internet, namely to any sites, services and social networks. You will be able to make video calls, including on Skype. This TV can also react with smartphones, tablets and other modern appliances. There is an opportunity to view the transmission in "online" mode, it is expanding the range of TV viewing around the world.

   And then, as in the science fiction film, you can not believe it, but it's true. Such TV sets, the set includes a remote control, where it is possible to change the channel "power of thought", the TV's power is through the air, since there are no wires in the same spirit. There is also a TV and a keyboard, the layout of the keys is the same as on a computer. The very small size of the keyboard, which is very convenient to use, it can be sold separately and can be combined with control. On one side of the panel are buttons to control the TV, the other - the keyboard for the web. There are five of the most important features that distinguish the Smart TV from normal TV .

   The first function - this is the Internet, where it is possible to connect to different sites, browse the channels in the "online" mode.

   The second function is considered to be listening to music and browsing the movies. In TV there are outputs for connecting flash drives.

   The third feature - the ability to obtain the necessary information. As soon as you press one or two buttons, the TV and tell you about the weather, and the latest news and so on.

   The fourth feature is that you can communicate in a variety of social networks.

   The fifth function - game. The TV is built sufficient number, both free and paid games.

   As a result, Smart TV will open your window to the world of opportunities.

Sony Bravia 40" Panel Problem Solution

Contact lcdledebooks@gmail.com

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Hisense LCD analysis

1, the power supply section - System 3.3Vstb

　　3.3Vstb standby 3.3V, converted from stand-by 5V, the standby is not controlled. PM power supply for the system, MbootFLASH power supply, power supply and other touch keys. This voltage is not normal will cause the machine does not start.

　　2, part of the system + 5V power supply ---

　　+ 5V system main 5V, stand-controlled design capacity? To 5A. For system + 2.5V_Normal, 33V_Normal, USB5V, 8G80 of nuclear power.

　　3, part of the power supply system --- 3.3V: 33V_Normal

　　3.3V system uses a dual layoutN5 and N4, the actual use of N5, namely AP1084-3.3V.The difference is not the same package, N5 temperature better, but the price is a little expensive.

　　4, the power part --- System 2.5V: + 2.5V_Normal

　　2.5V system for MST6i78 and 8G80-powered, stand-controlled.

　　5, the power part --- MST6i78 nuclear power: V the CC 1.2V

　　MST6i78 using nuclear power by 12V DC-DC converter and the size of about 1A. MST6i78 for the kernel. This voltage theoretical value of 1.26V, the actual design of the DC-DC is about 1.3V, the chip pin is about 1.27 ~ 1.28V.Noting chip pin voltage must be greater than 1.26V, below the words will cause the system to crash, reboot and other failures.

 

   

　　6, the power part --- LCD TCON supply: VCC-Panel

　　LCD TCON supply using the most commonly used MOS tube exchange circuit , switching power supply to achieve TCON control and input power options. If this part of the power output fault, such as U8 damage will cause the LCD screen has no output, the phenomenon manifested as black or gray screen (backlight time), or there is no sound in FIG.

　　7, the power part --- USB powered: 5V_USB1

　　8, the control section --- Standby control circuit: STANDBY

　　Standby control two-stage reverse way, when the power of the control pin PW_CTL MST6i78 default to a high impedance state so that the control terminal B V5 is high level , after two high reverse standby, power-up, output + 12V The system starts. After the system starts again based on EEPROM read control PM_CTL taken to the standby state, thereby controlling the whole organ is due to open state or standby state.

　　9, the control section --- backlight ON / OFF and dimming circuits

　　Adopt a common backlight control (BL-ON / OFF) circuit and a dimming circuit (BL-ADJUST). Dimming determined by the LCD screen, the DC dimming C1 bit 4.7uF; DC dimming system if C1 no welding , BL-ADJUST will cause voltage instability, resulting in the screen flashing fault. DC dimming voltage is too high or too low, dimming frequency and pulse width settings screen can also cause improper flashing, black and other failures.

　　10, the storage section --- MbootFLASH

　　mbootflash uses 32M of SPIflash, inside the storage system boot program and part of the system, the user data. System after power is directed through mboot first start, mboot complete system start and then start the main program (stored in NANDflash)

11, the storage section --- NANDFLASH

　　The main program is stored in the system in NANDFLASH, MST6i78 movement with a 1Gbit of NANDFLASH. Whether MBOOTflash or NANDFLASH, any fault will cause the machine can not start.

　　12, the storage section --- EEPROM

　　EEPROMN10 system, the main storage of plant data and user data; N13 is the HDMI HDCPEERPROM, using 24C04. EDID HDMI built-in to? The main program, namely NANDFLASH in.

　　13, the key circuit --- mechanical keys

　　Using mechanical buttons: XS8 to 3 the PIN ; R179, R180 to 2K2

　　14, remote control lighting and control circuits --- support, light

　　15, DDR circuit --- DDR3_H5TQ1G63BFR-12C

　　MST6i78 use of two 1Gbit DDR3, N15, N17. If DDR is faulty, causing the machine can not start back. By measuring the pin-by-pin impedance to determine whether the welding and other faults. Further work properly clk (R412, R413, R163, R164) DC level should be about 0.7V.

　　16, the interface section --- HDMI Interface

　　MST6i78 support 4? HDMI input, EDID using a built-in program mode. Meanwhile MST6i78 of ESD are strong, so close to the ESD HDMI interface devices do not need to mount. Lower right:

　　17, network interface chip interface section --- IP101A

　　6i78 integrates the MAC, but the need for an external PHY. The system uses the system as IP101A PHY interface chip, the power supply is 3.3V.

　　18, interface section --- HDTV and AV2 Interface

　　19, the interface section --- AV Interface

　　20, the interface section --- VGA Interface

　　Generic VGA interface circuits, and high-definition sound reuse. Note pin4 through VGA interface and can be programmed pin11 MBOOT, monitor print information.

 

21, the interface section --- AV output interface　　        conventional AV output amplification circuit .

 　　22, coaxial output circuit interface section ---

 

　　23, headphone output circuit interface section ---

　　MST6i78 headphone output directly from the output pin, through LRC (L45, R597, C455) to achieve the filtering effect, without any amplification, direct output. Headphone detection circuit PMD_MT directly directly on mute circuit, mute headset hardware control after insertion.

　　24, switch mute circuit

　　Universal switch mute circuit, pay attention to the audio output of the AV mute control is realized by this circuit, namely MUTE_602.

　　25, digital circuit for discharge

　　The system uses a new type of I2S? Word for discharge, N14 / TSA5707.

　　26, tuner section --- 5V-IF

　　12V After 10R / 2W of resistance partial pressure to the N24, N24 generated by linear regulator 5V-IF power , as the power tuner.

　　27, tuner section --- tuner

　　Digital tunerU1.

　　30, LVDS portion 28, tuner --- tuner part in the pre-amp circuit

　　Due to insufficient magnification tuner, in order to compensate for the acoustic attenuation of the signal, the tuner IF output needs to be increased in a pre-amplifier circuit. This is typical of the transistor common-emitter amplifier.

　　This part of the circuit parameters V18 prone to drift caused under TV image is not normal, the sound affect the image signal smearing and other issues. You can change or replace V18 R412 experiment.

   

　　29, tuner circuit portion --- SAW

　　Acoustic problems will cause a corresponding image or sound is not normal, can directly replace the SAW. SAW models need to use this machine, and can not be replaced.

　　30, LVDS part