lcd panel cof repair pdf free sample

Disclaimer And/ Or Legal Notices The reader is expressly warned to consider and adopt all safety precaution that might be indicated by the activities herein and to avoid all potential hazards. This E-Book is for INFORMATIONAL PURPOSES only and the author do not accept any responsibilities or liabilities resulting from the use of this information. While every attempt has been made to verify the information provided here, the author cannot assume any responsibility for any loss, injury, errors, inaccuracies, omissions or inconvenience sustained by anyone resulting from this information. Most of the repair tips and solution given should only be carried out by suitable qualified electronics engineers/technicians. Please be careful as all electrical equipment is potentially dangerous when dismantled. Any perceived slights of policy, specific people or organizations are unintentional.

Thank You for Contribution Here is to thank you to Mr. Vladimir, Mr. Lei Yang, Mr. Jonathan, Mr. Maronga Tapera, Mr. Ganesh and Mr. Huang. Because they had contributed the good repair information in part of this repair guides.

Part-1: Basic Theory of How an LCD Screen Work ........................ 12 How LCD/LED TV Works? ............................................................................ 14 How an LCD Display Work ............................................................................. 16 What are LCD Screen and LCD Panel? ........................................................ 19 T-con Boar Part Number ................................................................................. 20 TAB/COF IC Part Number ............................................................................. 20 LCD Panel Part or Model Number ................................................................. 21

Part-2: How an LCD/LED Screen Panel Works ................................ 22 Types of LCD Panel and Their Structure ...................................................... 23 The TFT LCD Structure .................................................................................. 24 Learn About LCD TV and TFT LCD Displays ............................................. 25 History of TFT LCD ......................................................................................... 25 What is TFT LCD? .......................................................................................... 25 TFT LCD - Electronic Aspects of LCD TVs and LCD Monitors ................ 26 Passive and Active Matrix LCDs ..................................................................... 27 Structure of Color TFT LCD TVs and LCD Monitors ................................. 29 Driving Circuit Unit .......................................................................................... 30 How TFT LCD Pixels Work ........................................................................... 31 Generating Colors ............................................................................................. 34 The TFT LCD Pixel .......................................................................................... 35

LCD/LED Screen Panel Repair Guide The Resolution of an LCD Panel with TAB/COF.......................................... 37 A Block Diagram of Driving an LCD Panel ................................................... 38 Gate Driver Signals & Supply Lines ............................................................... 38 How a CPT CLAA320WB02 LCD Panel Work ............................................ 39 Terminology of the T-con Board and LCD Panel.......................................... 40 Typical Waveform of Gate Driver Control Signals ....................................... 46 Timing Control (TCON) IC CM2681A-KQ Diagram................................... 51 If These Supply Voltages & Control Signals Missing What will Happen in LCD Panel? .................................................................................................. 52

Part-3: How to Troubleshooting & Repairing LCD/LED Screen & Panel ............................................................................................................. 53 Tools and Equipment for LCD Screen Panel Repair .................................... 54 How to Isolate Display Problem from Mainboard, T-con Board or LCD Panel? ................................................................................................................ 57 What is TAB Bypass Modification? ............................................................... 59 What is LCD Panel Cut Off Modification? ................................................... 63 TAB Bonding Machine ..................................................................................... 67 Laser Repair System ......................................................................................... 69

Part-4: LCD/LED Screen Panel Repair Case Histories ................... 71 How to Repair Double Images Problem on Samsung LCD Screen ............. 72 Samsung LTA320AP Series LCD Panel with Double Images Problem Solved ................................................................................................................. 87 Samsung LCD Panel with Display Problem Causing by Gate Driver Sides ............................................................................................................................. 90

LCD/LED Screen Panel Repair Guide TAB Bypass Modification Repair Case Histories .......................................... 93 How to Solve LG LCD Panel Display Upside Down Problem ...................... 98 How to Solve BOE HV320WXC-200 Panel Upside Down Problem .......... 102 Display Left Right Reverse Problem Solved ................................................ 104 White Screen Problem on V315B3-C04 T-con Board ................................. 106 No Display or Grey Screen - Common Fault on LG 370WX4-SLA1 (6870C-0158A) ................................................................................................ 108 AUO T460HB01 V0 (46T12-C01) T-con Board with Randomly No Display Problem ............................................................................................................ 109 LG 470WU5-SLA1(6870C-0140B) No Display Problem Solved ................ 110 How to Solve Samsung LCD TV Oil Painting Display Problem ................ 112 How to Repair LCD TV Symptom with Blue Screen and Vertical Bars .. 116 How to Repair the Display Washed Out Screen Problem .......................... 118 How to Easily Remove AS-15F or AS-15HF IC without 3 Minutes .......... 120

Part-5: All Good LCD/LED Screen Panel Repairing Information and Bonuses ......................................................................................124 TAB/COF IC Equivalent List ........................................................................ 125 TAB/COF Bypass List .................................................................................... 129 How to Login to the Universal LCD/LED TV Mainboard Factory Setting ............................................................................................................... 147 How to Solve Display Distortion (Oily Painting Display) Problem in Universal LCD/LED TV Mainboard ............................................................ 153 How to Solve Display Upside Down Problem in Universal LCD/LED TV Mainboard ....................................................................................................... 155

LCD/LED Screen Panel Repair Guide Samsung Display Distortion (Oily Painting Display) Repair Solution ...... 159 This LCD Panel Display Problem is Beyond Repair ................................... 164

BONUS-A: LG LED/LCD TV Interconnect Schematic Diagrams 32LD350-Interconnect…………………………..168 32LG40-Interconnect……………………………171 42LG70-Interconnect……………………………173 42LH20-Interconnect……………………………177 42LK520-Interconnect…………………………..179 42SL80-Interconnect…………………………….186 47GA6400-Interconnect…………………………190 47LG90-Interconnect……………………………202 47LH85- Interconnect……………………………206 55GA6400-Interconnect…………………………210 55LX6500-Interconnect…………………………222 79UB9800- Interconnect………………………...225

* Collection of T-con Board Repairing Information (Over 50+ Models of T-con Board) * LG TFT-LCD-Production-Process-Explained * LG 2012 Understanding T-con Troubleshooting & Training Guide

LCD/LED Screen Panel Repair Guide Highly recommended other great related repair information for you: With all these great repair information, it will help you in troubleshooting and repairing electronic and the other display devices: (Please click on the ebook cover to get more details) 1) Flat Screen TV Troubleshooting & Repairing Ebooks:

How to Use This Repair Guide 1) Yes, this repair guide not only can save you time and money, it also can earn more profit from repairing LCD/LED panel. Because of LCD/LED Panel is the most expensive spare part inside the TV and Monitor. If we can repair it, so the profit is quite high to compare repairing other section like PSU in TV.

2) Inside this repair guide, I will NOT or I will seldom to provide the repair case about the failure of “Bulged” or “Bad ESR” values of Electrolytic Capacitor/s. As a TV repairer it is a very first step to see and measure the PCB boards inside the TV. Because it is a very basic things as a repairer need to know or know how to measure it. I highly recommend using the Blue ESR tester to testing electrolytic capacitor.

3) If you don’t want to start from the basic theory, but just want to solve your TV display problem, you can direct refer to the chapters 3, 4 & 5. So it will directly to show you what’s wrong on this type of display symptom. Also the LCD and LED Backlight is not writing in this ebook, because I had wrote a lot this title in my V2, V3 and V4 ebook series. 4) When I’m mention “LCD” word in this ebook, actually it is included the “LED” at the same time. So I don’t to write too many LED word in this ebook to save more space and reduce some file sizes in this ebook.

5) After you have finished reading this repair guide, I believe that you will have the confident to repair LCD/LED TV Panel now. It is because of we know how the LCD/LED Panel is working, why this display symptom is occur and also know how to troubleshooting it! The LCD/LED Screen is the most expensive cost of the TV. Normally when the Panel is beyond repair, this TV will no point to continue repair. Either replaces a new or working Panel with reasonable price, or just selling their PCB board as it to the used spare part market. Nowadays, repairing the LCD/LED Panel has a high profit margin in TV or Monitor repair!

LCD/LED Screen Panel Repair Guide Nowadays, lots of the LCD & LED TV is in the market now. And this is the “peak season” these LCD & LED TV need to repair. But I found that, lots of the LCD TV or even LED TV I can found it in the recycling centers or factory! All these TV will be send to scrap and disposal as reuse their material only. So it is not only cause the money waste but it also increases the electronic waste on the earth. Finally found the answer is because of these scrap LCD/LED TV problem can’t be repair or not worth to repair it. Most of the symptom is because of “Display Problem”! The TV repairer told customer that this “Display Problem” is because of the Panel issue and no spare part to replace/repair or the repair cost is very expensive. But I can say their answer is not 100% true! Because I had tried before to repair these scrap LCD/LED TV, if the TV not crack screen, leakage their liquid crystal in the panel or Samsung Panel without Gate/Y- TAB, their success rate to repair these scrap TV is about 60~70%! ! So the actual the answer is because lots of the TV repairer they don’t know how to repair the LCD/LED Screen Panel. That’s why I created this ebook to help TV repairer to increase their troubleshooting & repairing knowledge in LCD screen panel repair. And the highest profit to repairing TV is repair the TV screen/panel problem. 

How LCD/LED TV Works? Before we repair the LCD/LED TV, we must know how it works. So when we repair the LCD/LED screen or panel, we need to know how it works too.

2) Inverter Board/ LED Driver Board * For LCD TV, the inverter board receives 24V (normally) from PSU and received a backlight on signal from Mainboard, it will generate and output the AC voltages to start-up the CCFL lamps. So the backlight unit (BLU) can working properly and supplies the light to Panel. * For LED TV, the LED Driver board receives 24V (but different design will have different voltages. Please refer to their appropriate LED Driver board specification) from PSU and received a backlight on signal from Mainboard, it will step-up the DC voltage and output the DC voltage to start-up the LED Strip.

4) T-con Board When T-con board received the voltage supplies and LVDS signals from Mainboard, the T-con board will start working. The T-con Board converts the LVDS signal to TTL signals and through Timing Control circuit. After that generate the Data signals send to Source Driver Board. T-con board also generates the DC-DC voltages, Gamma circuit and control signals to control the Panel Glass working. For more details on how T-con board work, please read on chapter-2, How T-con Board works.

5) LCD Screen When the LCD Screen received the voltage supply and LVDS signals from Mainboard, it can show the display on the screen. But we also need the backlight to supply the light to Panel, so that we can see the picture or movie on the screen. If no backlight, it looks like no display but using a torch light shot to the screen, we can see the images on the screen. So LCD Screen is use to convert the videos/digital signals to images and the images can see by our eyes.

How an LCD Display Work Liquid Crystals In school you learned that matter has three distinct states; solid, liquid, and gas. However, there are states of matter that may fall between these states, like liquid crystals. Basically they are crystals that hold their orientation (shape) but can flow similar to liquids. Their molecules point in same direction with respect to each other like in a solid, but they are free to change position like in a liquid. Think of a handful of pencils. They collectively hold their shape at rest, but change shape when you squeeze or let go of them.

There are different phases and types of liquid crystals that perform differently. Small amounts of pressure, heat, and/or electricity can cause liquid crystals to change in some way. For LCDs we are interested in the electricity aspect, but pressure and heat are side effects that have to be dealt with. This is why LCDs have a limited operating range and distort when you press on the screen. Liquid Crystal Display A Liquid Crystal Display is composed of a light source (backlight), a Liquid Crystal Panel, and a driving circuit. We start with a light source at the back of the panel composed of thin fluorescent bulbs (CCFLs - Cold Cathode Fluorescent Lamps). This light passes through filters to help create a uniform light source. Then the light passes through the Liquid Crystal Panel which is composed of thousands of pixels that control the flow of light through the panel to make images.

LCD/LED Screen Panel Repair Guide Liquid Crystal Panel Below (on the left) is a cross section of a liquid crystal panel. The key to an LCD"s operation is the polarizer. The polarizers only allow a certain wavelength of light to pass through. These two polarizers are mounted at a 90 degree angle with respect to each other, which prevents light from passing through. The liquid crystals are used to twist the light beam 90 degrees and allow light to pass through that cell. Color comes from a simple light filter.

What are LCD Screen and LCD Panel? The words of LCD or LED screen or LCD or LED panel, actually both are different things. The LCD screen is meaning whole screen included Backlight, Metal Box (hold the backlight), T-con board and Panel Glass. Some LCD Screen also included the inverter board together and it is call as LCD Module. The LCD Panel is meaning the Panel Glass only. Sometime it also included the T-con board or Timing control section in their Source Driver board.

The above picture is to show different types of LCD Panel. Type (1) & (2) is the old technology of LCD Panel used. The latest technology is using the (3) and (4) types design now. One more LCD Panel design is without the external Gate Driver COF/TAB on both sides.

History of TFT LCD Liquid crystal was discovered by the Austrian botanist Fredreich Rheinizer in 1888. "Liquid crystal" is neither solid nor liquid (an example is soapy water). In the mid-1960s, scientists showed that liquid crystals when stimulated by an external electrical charge could change the properties of light passing through the crystals. The early prototypes (late 1960s) were too unstable for mass production. But all of that changed when a British researcher proposed a stable, liquid crystal material (biphenyl). Today"s color LCD TVs and LCD Monitors have a sandwich-like structure (see figure below).

What is TFT LCD? TFT LCD (Thin Film Transistor Liquid Crystal Display) has a sandwich-like structure with liquid crystal filled between two glass plates.

TFT LCD - Electronic Aspects of LCD TVs and LCD Monitors Electronic Aspects of AMLCDs The most common liquid-crystal displays (LCDs) in use today rely on picture elements, or pixels, formed by liquid-crystal (LC) cells that change the polarization direction of light passing through them in response to an electrical voltage. As the polarization direction changes, more or less of the light is able to pass through a polarizing layer on the face of the display. Change the voltage, and the amount of light is changed. There are two ways to produce a liquid-crystal image with such cells: the segment driving method and the matrix driving method. The segment driving method displays characters and pictures with cells defined by patterned electrodes. The matrix driving method displays characters and pictures in sets of dots. Direct vs. multiplex driving of LCD TVs.

The segment drive method is used for simple displays, such as those in calculators, while the dot-matrix drive method is used for high-resolution displays, such as those in portable computers and TFT monitors. Two types of drive method are used for matrix displays. In the static, or direct, drive method, each pixel is individually wired to a driver. This is a simple driving method, but, as the number of pixels is increased, the wiring becomes very complex. An alternative method is the multiplex drive method, in which the pixels are arranged and wired in a matrix format. To drive the pixels of a dot-matrix LCD, a voltage can be applied at the intersections of specific vertical signal electrodes and specific horizontal scanning electrodes. This method involves driving several pixels at the same time by time-division in a pulse drive. Therefore, it is also called a multiplex, or dynamic, drive method.

LCD/LED Screen Panel Repair Guide In passive-matrix LCDs (PMLCDs) there are no switching devices, and each pixel is addressed for more than one frame time. The effective voltage applied to the LC must average the signal voltage pulses over several frame times, which results in a slow response time of greater than 150 msec and a reduction of the maximum contrast ratio. The addressing of a PMLCD also produces a kind of crosstalk that produces blurred images because non-selected pixels are driven through a secondary signal-voltage path. In active-matrix LCDs (AMLCDs), on the other hand, a switching device and a storage capacitor are integrated at the each cross point of the electrodes. The active addressing removes the multiplexing limitations by incorporating an active switching element. In contrast to passive-matrix LCDs, AMLCDs have no inherent limitation in the number of scan lines, and they present fewer crosstalk issues. There are many kinds of AMLCD. For their integrated switching devices most use transistors made of deposited thin films, which are therefore called thin-film transistors (TFTs). The most common semiconducting layer is made of amorphous silicon (a-Si). a-Si TFTs are amenable to large-area fabrication using glass substrates in a lowtemperature (300°C to 400°C) process. An alternative TFT technology, polycrystalline silicon - or polysilicon or p-Si-is costly to produce and especially difficult to fabricate when manufacturing largearea displays. Nearly all TFT LCDs are made from a-Si because of the technology"s economy and maturity, but the electron mobility of a p-Si TFT is one or two orders of magnitude greater than that of an a-Si TFT. This makes the p-Si TFT a good candidate for an TFT array containing integrated drivers, which is likely to be an attractive choice for small, high definition displays such as view finders and projection displays.

Structure of Color TFT LCD TVs and LCD Monitors A TFT LCD module consists of a TFT panel, driving-circuit unit, backlight system, and assembly unit. Structure of a color TFT LCD Panel:

1. LCD Panel - TFT-Array Substrate - Color Filter Substrate 2. Driving Circuit Unit - LCD Driver IC (LDI) Chips - Multi-layer PCBs - Driving Circuits 3. Backlight & Chassis Unit - Backlight Unit - Chassis Assembly It is commonly used to display characters and graphic images when connected a host system. The TFT LCD panel consists of a TFT-array substrate and a color-filter substrate.

The TFT-array substrate contains the TFTs, storage capacitors, pixel electrodes, and interconnect wiring. The color filter contains the black matrix and resin film containing three primary-color - red, green, and blue - dyes or pigments. The two glass substrates are assembled with a sealant, the gap between them is maintained by spacers, and LC material is injected into the gap between the substrates. Two sheets of polarizer film are attached to the outer faces of the sandwich formed by the glass substrates. A set of bonding pads are fabricated on each end of the gate and data-signal bus-lines to attach LCD Driver IC (LDI) chips

Driving Circuit Unit Driving an a-Si TFT LCD requires a driving circuit unit consisting of a set of LCD driving IC (LDI) chips and printed-circuit-boards (PCBs). The assembly of LCD driving circuits.

To reduce the footprint of the LCD module, the drive circuit unit can be placed on the backside of the LCD module by using bent Tape Carrier Packages (TCPs) and a tapered light-guide panel (LGP).

How TFT LCD Pixels Work A TFT LCD panel contains a specific number of unit pixels often called subpixels. Each unit pixel has a TFT, a pixel electrode (IT0), and a storage capacitor (Cs). For example, an SVGA color TFT LCD panel has total of 800x3x600, or 1,440,000, unit pixels. Each unit pixel is connected to one of the gate bus-lines and one of the data bus-lines in a 3mxn matrix format. The matrix is 2400x600 for SVGA. Structure of a color TFT LCD panel.

LCD/LED Screen Panel Repair Guide Because each unit pixel is connected through the matrix, each is individually addressable from the bonding pads at the ends of the rows and columns. The performance of the TFT LCD is related to the design parameters of the unit pixel, i.e., the channel width W and the channel length L of the TFT, the overlap between TFT electrodes, the sizes of the storage capacitor and pixel electrode, and the space between these elements. The design parameters associated with the black matrix, the bus-lines, and the routing of the bus lines also set very important performance limits on the LCD. In a TFT LCD"s unit pixel, the liquid crystal layer on the ITO pixel electrode forms a capacitor whose counter electrode is the common electrode on the color-filter substrate.

A storage capacitor (Cs) and liquid-crystal capacitor (CLC) are connected as a load on the TFT. Applying a positive pulse of about 20V peak-to-peak to a gate electrode through a gate bus-line turns the TFT on. Clc and Cs are charged and the voltage level on the pixel electrode rises to the signal voltage level (+8 V) applied to the data bus-line. The voltage on the pixel electrode is subjected to a level shift of DV resulting from a parasitic capacitance between the gate and drain electrodes when the gate voltage turns from the ON to OFF state. After the level shift, this charged state can be maintained as the gate voltage goes to -5 V, at which time the TFT turns off. The main function of the Cs is to maintain the voltage on the pixel electrode until the next signal voltage is applied. Liquid crystal must be driven with an alternating current to prevent any deterioration of image quality resulting from dc stress. This is usually implemented with a frame-reversal drive method, in which the http://www.LCDRepairGuide.com/Screen-Repair/

LCD/LED Screen Panel Repair Guide voltage applied to each pixel varies from frame to frame. If the LC voltage changes unevenly between frames, the result would be a 30-Hz flicker. (One frame period is normally 1/60 of a second.) Other drive methods are available that prevent this flicker problem. Polarity-inversion driving methods.

In an active-matrix panel, the gate and source electrodes are used on a shared basis, but each unit pixel is individually addressable by selecting the appropriate two contact pads at the ends of the rows and columns. Active addressing of a 3x3 matrix

By scanning the gate bus-lines sequentially, and by applying signal voltages to all source bus-lines in a specified sequence, we can address all pixels. One result of all this is that the addressing of an AMLCD is done line by line. Virtually all AMLCDs are designed to produce gray levels - intermediate brightness levels between the brightest white and the darkest black a unit pixel

LCD/LED Screen Panel Repair Guide can generate. There can be either a discrete numbers of levels - such as 8, 16, 64, or 256 - or a continuous gradation of levels, depending on the LDI. The optical transmittance of a TN-mode LC changes continuously as a function of the applied voltage. An analog LDI is capable of producing a continuous voltage signal so that a continuous range of gray levels can be displayed. The digital LDI produces discrete voltage amplitudes, which permits on a discrete numbers of shades to be displayed. The number of gray levels is determined by the number of data bits produced by the digital driver.

Generating Colors The color filter of a TFT LCD TV consists of three primary colors - red (R), green (G), and blue (B) - which are included on the color-filter substrate. How an LCD Panel produces colors.

The elements of this color filter line up one-to-one with the unit pixels on the TFT-array substrate. Each pixel in a color LCD is subdivided into three subpixels, where one set of RGB subpixels is equal to one pixel. (Each subpixel consists of what we"ve been calling a unit pixel up to this point.) Because the subpixels are too small to distinguish independently, the RGB elements appear to the human eye as a mixture of the three colors. Any color, with some qualifications, can be produced by mixing these three primary colors. The total number of display colors using an n-bit LDI is given by 23n, because each subpixel can generate 2n different transmittance levels. .

Gate Driver Signals & Supply Lines: DIO1, DIO2, SCLK, R/L, XON, OE1, OE2, OE3, VGG, VEE, VDD, VSS. (This Gate Drive Signals & Supply lines information is use for the LCD Panel Cut Off Modification use)

This VGH (VGate High) voltage was generated by DC-DC circuits. And their voltage is about 20V ~30V but it will depends on the T-con board design. The feature of VGH voltage is to supply to the Gate Driver Board as a “Switch ON” feature. It can switch on the TFT cells in LCD Panel and display shows.

In order to solve the problem of image-retention effect of TFT-LCD, the technique of XAO function (power off control) is mostly used at present. XAO function means that XAO is set to low level when the display is turned off. For example, the logic low level is set to 0˜3.3 v, and thus all outputs of the gate driver will be shifted to high level at the same time and all TFT will be turned on. The charge stored on the CS can thus be discharged and the imageretention effect can be eliminated. However, the common method of using XAO function is to send XAO signal into logic control circuit and to convert low level to high level output through level shifter. After the display is turned off, much charge on the capacitor will be discharged since the voltage of power supply is maintained only by the capacitor and all TFT at low level will function at the same time. Therefore, when the pulse of XAO reaches, the gate voltage of all TFT are all shifted to VGH, and thus a large current is produced at the moment in which the gate of TFT on gate driver circuit is activated. This large current may cause the trace on gate driver circuit to burn. Furthermore, VDD voltage will also decrease rapidly and thus causes the conversion of the level shifter to fail and the XAO function to lose efficacy.

If These Supply Voltages & Control Signals Missing What will Happen in LCD Panel? (A) If missing or abnormal supply voltages of: 1.VGH (VON): Display will slow motion, white screen, display darkness or display blank. 2. VGL (Voff): Ghosting display, washed out display with vertical lines/bars. 3. VDA (Avdd): Display fully of vertical color lines/bars. 4. VDD (Vlogic): No display.

Tools and Equipment for LCD Screen Panel Repair Before starting repair LCD Panel, the first thing is we must have the right tools. Without the tools, we can’t do anything even you know how to repair it. The common tools like Multimeter, cutter, soldering iron, Oscilloscope (50MHz ~100Mhz, optional) and etc it is a common use tools. But I will list out some special tools to helps TV repairer to repair LCD Panel easily. 1) Magnifier: more than 60X is better. Also prepare a small magnifier in the pocket, when need to see a small thing or lines it will helps to you.

2) A clean and big table: To suitable for big size LCD Panel repair. Like the photo above. Also put the fluorescent light below the table as a backlight of Panel.

LCD/LED Screen Panel Repair Guide 4) LCD/LED Panel Tester: This is a MUST have tool to let us easily diagnosis LCD Panel working or not, and no more guess game in LCD Panel repair. If you know how to setting TV Mainboard and programming their firmware through ISP Programmer, you can use the Universal TV Mainboard as a LCD Panel Tester. Because the Universal TV Mainboard can support more range of LCD Panel. It can support 15inches ~42 inches or 26 inches ~84inches LCD Panel.

How to Isolate Display Problem from Mainboard, T-con Board or LCD Panel? This is an important subject to all TV repairers. Because every day the TV repairer will facing many TV display problem on their workbench. So they need to know the faster way to how to isolate TV display problem.

a) First is call out the TV OSD Menu (just click on the remote control MENU button is ok). If the OSD Menu can show good display, that’s mean the problem is in the Mainboard or there LVDS cable/s there. But when the display problem still present on the OSD Menu there, that mean higher percentage is their T-con board or LCD Panel defective. But this method is not 100% accurate.

b) So using the LCD Panel Tester to test the T-con board and we can know the result directly. Or we can also using the Universal TV Mainboard as an LCD Panel Tester. If you know how change their setting. Besides these LCD Panel testers, actually I also found other design LCD Panel tester in the market now. But compare with their price and performance, I think these two types LCD Panel Tester is ok to use. Unless you’re repair the 4K (or above) type LCD Panel.

2) T-con Board or LCD Panel? In this section, I will recommend to read on this ebook “Part-3: LCD Panel Cut Off Modification”. Actually this method not only can repair the display Double Images problem, it cans also diagnosis the LCD Panel at the same time. Even this method is not 100% accurate but it still acceptable. Compare to the TV repairer have buy the TAB Bonding Machine. Normally they are just directly replacing a working Tcon board to testing it. Even that T-con was built-in the Source PCB board. Their reason is this method will save time and increase the repairing speed. Because they need to repair over 200 pcs LCD panel per month. But the question is, when all these LCD Panel came in with different brands and models, so how can they prepare all these T-con board? It will stuck the cash flow for a company. So why not learn the troubleshooting & repairing skills to save money and even troubleshooting time if you know exactly how it work.

What is TAB Bypass Modification? This repairing method only can apply to the LCD Panel with external Gate Driver TAB/COF. If the LCD Panel Gate Driver COF built-in the LCD Panel glass, so this method will not work to this LCD Panel. The TAB Bypass Modification method is use to solve the LCD Panel Gate Driver control lines and supply voltage lines circuit break inside the glass! If your LCD Panel facing this problem, even you have the expensive TAB Bonding Machine also can’t help in this issue. How to do the TAB Bypass Modification? First we need to standby some tools and spare parts before starting to do the TAB Bypass Modification. 1) Multimeter 2) Magnifier- more than 60x is better 3) Thin copper wire (0.1mm)

4) TAB Bypass List (inside this ebook Part-5: TAB/COF Bypass List) * If you know where to connect from T-con board or Source PCB to TAB IC correct point, then no need to refer to this list. 5) Fine tip soldering iron For example, when a TV problem is Display Slow Motion symptom, normally it is because of their VGH voltage missing on the Gate Driver side. Using Multimeter to measure VGH voltage is present on the Source PCB or not. If yes, continue to checking the Y-TAB testing point. With the help of TAB Bypass List, we know that which point is the Y-TAB VGH voltage point. If no any VGH voltage here or the voltage drop a lot causing by supply line increasing http://www.LCDRepairGuide.com/Screen-Repair/

LCD/LED Screen Panel Repair Guide resistance. Now we can use the thin copper wire to solder Y-TAB VGH voltage point. After that find the VGH point on Source PCB or T-con board there and solder that thin copper wire. That’s all. Sometime the circuit break inside the LCD Panel glass is not just one line only. Maybe 2 or more lines, especially their top corner side if broken a bit. It can be more than 10 lines too! If TAB part number not in the list or we don’t know which point is for which signal line, so how to solve this problem? Actually we can use the Magnifier over 60X to trace their lines from Source PCB to the Y-TAB there. If the LCD Panel top corner is broken, so we can use this method to repair the LCD Panel. Because when the Panel top corner side is broken, it will need to connect more than 5 or 10 lines! So it will hard to get the full TAB voltage point, unless you use this method to find it out. Below is a sample photos on how to do TAB Bypass Modification:

2. Checking the voltage values on Y-TAB to make sure that supply voltages or signals is reaching there. If not, that’s mean this line is circuit break inside the Panel glass.

What is LCD Panel Cut Off Modification? This repairing method is for diagnosis LCD Panel when occur short circuit or leakage inside the Panel. Even this method is not 100% accurate, but it has higher rate as over 80% accuracy. From the theory of how is LCD Panel work, ‘most’ of the LCD/LED Panel has both sides of Gate Driver, especially for HD LCD Panel or above level Panel. That’s why, when the LCD Panel one of their Gate Driver side failure or short circuit, we can diagnosis and cut off their shorted line/s to save an expensive LCD Panel.

A) When to use this “LCD Panel Cut Off Modification Method”? 1) When LCD Panel symptom is Double Images or Jittering/Jumping display. 2) When the LCD Panel problem has unstable Horizontal Lines/Bars. 3) When suspect one of the Gate Driver side has short circuit in signal lines or voltage supply lines. 4) The LCD Panel has fully of horizontal thin lines on the screen. 5) The strange display problem occurs in LCD Panel. When facing this type of display problem, we can try to use this method to isolate the problem is occurs in Gate Driver side or not. Or which Gate Driver side is causing the problem occurs. 6) To isolate the display problem in LCD Panel or T-con board itself.

B) How to use this “LCD Panel Cut Off Modification Method”? We must know which are the Gate Driver control signal lines (included the clock lines) and voltage lines (VGH, VGL and so on). Normally these signal and voltage lines are going through the first X-TAB (X1) to right side Gate Driver and the last X-TAB (Xn) to left side of Gate Driver.

LCD/LED Screen Panel Repair Guide When a display problem occurs and suspects it is the T-con board or LCD Panel failure: 1) With T-con Board: If this LCD Panel has the T-con board, it is easy to do the Cut Off Modification testing. Just remove their FPC cables one by one. For example: a) First write down the Gate Driver control signals and supply voltage values on the paper. b) Power off TV, remove one side of FPC cable from T-con board. Now power on TV and see the display screen result. If half of the display normal and another half is blank (or no display) refer to the photo below, that’s mean, the problem was in the right side of Panel Gate Driver. And confirm this is a LCD Panel problem. Remember to write down their signals and supply voltage values.

So find the failure Right side of Gate Driver control signals (if that is Double Images problem, Display Jumping, Horizontal bars/lines Jittering and so on), CKV1, 2, 3…, CKVB1, 2, 3…, STVP, VCST, OE and so on. For how to cut off the signal lines please refer to the Part-4: Double Images repair case histories. If the display problem is slow motion on the screen, you need to find their supply voltage lines like VGH (most of the time is this voltage failure), http://www.LCDRepairGuide.com/Screen-Repair/

LCD/LED Screen Panel Repair Guide DVDD, VGL and so on to do the TAB Bypass Modification. If that LCD Panel is without the external Y-TABs, and the voltage values are normal, that’s mean this LCD Panel is beyond repair. Because the problem was inside the Gate Driver glass, so nothing we can do for this LCD Panel.

If the result is both side also show failure display on the screen and their voltages recorded were all normal, that’s mean this LCD Panel is NOT worth to repair it, if LCD Panel is no Y-TAB on both sides of Gate Driver. If one or both sides have the Y-TABs there, then you need to use the TAB Bonding Machine to replace their Y-TABs to save the LCD Panel. But some time with this situation, about 20% of LCD Panel with above symptom (both sides show bad display) can be repaired. But this LCD Panel is not last long. If the result is both side also show failure display on the screen and their voltages recorded for T-con board is abnormal, then we can suspect the problem is in the T-con board not the LCD Panel! From here we can isolate the problem is in the T-con or LCD Panel defective! For big inches LCD Panel with 4 FPC cables, it also uses the same method. Where left side is 2 FPC cables and right is another 2 FPC cables.

For the LCD Panel without T-con board and no any external Y-TABs it is hard to swap testing both sides of Gate Driver. But we still can cut off their Gate Driver supply voltages like VGH, VGL and DVDD (3.3v) for one side first. So the display will show half screen is ok, another half screen is blank/black. So their result will same as “With T-con” method. If the first half display can show a good images but another one is bad images, this LCD Panel can be repair. If both sides also showing bad images, that’s mean this LCD Panel is beyond repair. To learn how to cut off the signal lines please refer to the “Part-4: Double Images repair case histories” for more details.

The main purpose of TAB Bonding Machine is to use for bonding the TAB/COF on the LCD Panel only. Is the TAB Bonding Machine is a compulsory tool to repair LCD Panel? My answer is not really. Because it will depends on the repairing business. For example how many quantity of LCD Panel need to repair every month? If your answer is HUGE over 50 or 100 pcs above, I will highly recommend you buy a good TAB Bonding Machine to earn more profit from this field.

The TAB Bonding Machine is not a cheap tool and their cost for the TAB & ACF cleaning chemical, ACF glue and so on is very high. So if your repairing business didn’t have this repairing volume on LCD Panel, I will not recommend buying it. But when you buy the TAB Bonding Machine, make sure you’re choose a good quality with a good support seller or manufacturer, if not it will waste your money and time!

Latest LCD Panel repair equipment is Laser Repair System. This is a new repair machine for LCD Panel repair. The price for this machine is very expensive than TAB Bonding Machine. It is about 10X more expensive than the TAB Bonding Machine! This LCD Panel repair equipment is use by the LCD Panel manufacturer or the LCD Panel Repair manufacturer only. This laser repair system can repair: 1) LCD Panel bright dots on the screen - Actually they just use this laser system to “turn off” that bright dot only. Where this bright dot after laser machine repair, it will change to “black dot” only. So a one black dot will hard to see or scan by human eyes. 2) It can remove the circuit short (ITO) inside Panel. 3) And so on.

All these troubleshooting & repairing methods will not write again in Part-4 repair case histories to save some pages and file size of this ebook. http://www.LCDRepairGuide.com/Screen-Repair/

How to Repair Double Images Problem on Samsung LCD Screen Nowadays, lots of the TV repairer complaint that this type of screen problem is beyond repair. But I can say NOT ALL. Because the double images screen problem for Samsung brand panel is about 95% is their Panel defective. For other brands Panel maybe is their T-con board or Panel (is about 50-50%). For Samsung brand Panel, if their Panel without external Y-TAB(COF) (or call it as Gate Driver IC), where their Gate Driver IC (COF) are built inside the Panel left and/or right side, this type of Panel has lower successful rate to repair it. In the market now, when I search internet and I found that lots of SONY & TOSHIBA TV owner complaint their TV display problem and also frustrated why these branded TV quality so bad? Actually this is because they using Samsung LCD Panel inside their TV! Especially the low end models LCD/LED TV. The Sony TV has a good Mainboard design and good quality in PSU board. Unfortunately it is using the Samsung Panel for their TV. Why LCD screen occur “Double Images” problem in the Panel? It is because of their Gate Driver control signals are shorted or leakage to each other. So it can happen in T-con board Gate Driver control signal section, ITO line/s inside the Panel, external Gate Driver IC (Y-TAB or Y-COF) shorted internally or internal/built-in Gate Driver IC in the left and/or right side Panel. So what’s the solution to repair Display Double Images problem? First we need know what and where are the Gate Driver control signal lines. For Samsung LCD Panel, most popular is their CKV (CKV1, 2 &…), CKVB (CKVB1, 2 & …) and STVP control signal lines. Please refer to Part-3: “LCD Panel Cut Off Modification Method” for more details. Below have two repair case of Double Images for Samsung Panel. One has Tcon Board with two FPC cable. Another one is without FPC cable and their Tcon section is built-in the LCD Panel Source PCB there.

This LCD TV complaint problem was Display Double Images and Jittering problem. Test each video inputs like TV Channel, OSD Menu and the AV modes all same symptom. The TV bottom of 2/3 display has horizontal thin lines there.

We need know isolate the problem first. Because of this LCD Panel has a T-con with two FPC cables (left & right), so we can took out the FPC cable one by one, not both together. Refer to the “LCD Panel Cut Off Modification Method” for more details in Part-3. The result is when took out the left side FPC cable, the right side screen can show a good display. But when took out the right side FPC cable, the left side screen show a double images like before. That’s mean the problem is from left side Gate Driver IC control signal lines. From here we know that this LCD Panel can be manual repair! So we need to find out where are their left side Gate Driver IC control signal lines. Refer to the photos below,

LCD/LED Screen Panel Repair Guide On the right side of FPC connector, around that found the Gate signals like: CKV1, CKV2, CKV3, CKVB1, CKVB2, CKVB3 and STVP. After found their Gate signals, next step is: a) If this LCD Panel has the Y-TAB or Y-COF (Gate Driver IC) externally, you can use TAB Bonding Machine to replace these Y-TABs (or you can check one by one which Y-TAB is defective, normally that’s the Y1failure). This method of repair their weakness is cost very high, you need to buy an expensive TAB Bonding Machine, related tools, spare parts like COF IC, ACF and etc. Not only that, you also need to know how to operate the TAB Bonding Machine properly, if not it will waste your time and money. But with this method of repair LCD Panel, the images quality will maintain as their spec. b) If this LCD Panel didn’t have Y-TAB externally like most of Samsung LCD Panel, you can use “LCD Panel Cut Off Modification Method” to manually repair. Actually this modification method is the lowest cost to TV repairer. But modification weakness is after repair LCD Panel images quality will decrease a bit but acceptable.

Since this ebook is design to using the manually method to repair LCD Panel, so I will write for this way. After found all the Gate signals on T-con board, is this all Gate signals need to cut off all or just one or two lines only? It will depends on how serious of the shorted or leakage inside LCD Panel. For example, if just cut off the CKV1 and CKVB1 the display images is back to normal, than just cut off these two signal lines is enough. But most of the time, it needs to cut off CKV1, 2, 3 and CKVB1, 2 &3. Also maybe need to cut off another signal line like STVP and so on (like T1, T2, VCST…). For this repair case, after found the Gate signals, roughly we know where the Gate signals position on that FPC connector is. So we can refer it to the left side of FPC connector as photo below:

Finally this Samsung LTA400HM04 LCD Panel back to normal now. With this easily method and nearly NO cost to successful repair LCD Panel. Even their images quality not different much and confirm this method is work. Because this TV after repaired over 1 year still in use.

This Samsung LCD Panel comes with T-con board and two FPC cables. Beside the FPC cables to cut off the Gate signals, actually we also can cut off the Gate signals on Source PCB board. Especially the LCD Panel design without T-con Board and the Timing Control section was built in the Source PCB Board. Since I had show the method on how to cut off from FPC cables, so this time is to learn how to cut off from Source PCB Board. Actually Samsung LCD Panel has many models LCD Panel without T-con board, but this time I can’t get one in hand, so I using this LCD Panel as a repair case for LCD Panel without T-con board. When the LCD Panel doesn’t has T-con board, so how to do the cut off modification of this Panel? Actually we can look at the Source PCB board near X-TAB connection there to find the marking code of CKV, CKVB and so on Gate Driver signals. Most of the time, these marking code are located on the first X-TAB and last X-TAB position.

The Rules of LCD Panel Cut Off Modification: 1) CANNOT cut off both sides of Gate Driver signals, it will causing the LCD Panel not working or create another problem for this Panel. 2) Don’t cut off the circuit line too nearly the X-TAB contact pins there. If not when the line need to re-solder back, it will cause very hard to soldering the line. 3) Use a good solder and fine tip soldering iron to do the soldering job.

Samsung LTA320AP Series LCD Panel with Double Images Problem Solved This repair case is share by my member and as a sample to let you learn if the LCD Panel doesn’t have T-con board and just one X-TAB only on the Source PCB board. So what to do with this type of LCD Panel? Read this article and remember what you had learned from this ebook. So you will roughly know how to do it.

As usual with this type of Double Images problem, directly go to checking their T-con board. Because of type of LCD Panel design is just has one big X-TAB IC only, and also no any Y-TAB on both sides of Panel. Actually the Gate Driver signal lines are on the both left & right sides of this big X-TAB IC pins as photo below:

Find out the Gate Driver signal lines in front of this big X-TAB IC. Try to find any marking code for Gate signals, if not, try to checking their voltages about 8V~10V (is stable voltage values). It will depend on inches Panel and design, so their voltage will a bit different. First try to find out the Gate signals, after that using a small stationery knife carefully to cut off these Gate signals one by one follow to see the display is ok or not. Remember when cut off the lines MUST off the power TV! If the cut off all the left side Gate signals also same problem, then you need to re-solder back the cut off lines. After that find right side Gate signals lines to do the same thing. After cut off the Gate signals line, the display is change to a bit Ok, continue to cut off other signal lines, until the display is back to normal.

Samsung LCD Panel with Display Problem Causing by Gate Driver Sides Did you see any dirty or black dot inside the edges of Panel Gate Driver side? An LCD Panel without T-con board and no Y-TAB on both left and right side, also their display problem is causing by Gate Driver side but don’t know how to repair it (for example Samsung LTY320AP04 Panel). The Gate Driver side/s symptom for example: horizontal lines/bars with jumping, jittering and so on.

If you’re facing this problem before, you need to check the LCD Panel Left and Right sides of the edges Panel there. If you found a dot like photo below, it is confirm dirty dot is a location of shorted or burnt ITO lines inside the Panel glass.  Remember, if both of the left & right sides of Panel also have this dirty dot inside the glass, so this LCD Panel is beyond repair.

The solution to repair this problem is to use a small saws or related tools to remove the dirty shorted dot on the edges of Panel. Remember to use the magnifier to see more details in it. WARNING! To repair this type of Panel problem, you will take the risk!

Before do this repair, you MUST ask your customer or the TV owner permission first. Because when fail to remove the shorted dot, the LCD Panel liquid crystal maybe leakage after you use the wrong tools to do it. If the liquid crystal leakage from the Panel, this Panel will beyond repair! Be careful!

TAB Bypass Modification Repair Case Histories For details of what is TAB Bypass Modification, please refer to Part-3: “What is TAB Bypass Modification”.

A) LCD Panel: Samsung LTA320WT-L05 T-con Board: 320WTLF3C2LV0.3 Symptom: Display Slow Motion and a bit Darkness This 32 inches LCD TV display problem is Display Slow Motion and the image is darkness.

LCD/LED Screen Panel Repair Guide All the above voltage values are normal. So next step is, from our previous experience when the display problem is slow motion, it is causing by the VGH (VON) voltage missing on Gate Driver side. This LCD Panel has the Y-TAB on Gate Driver side.

Here has a good secret tip for you. When we don’t know the TAB/COF which point is what voltage values is. Actually we can use a 10Kohm ¼ resistor to searching each point in TAB film. So with this method it will prevent the higher voltage damage the lower voltage lines on the TAB IC there.

LCD/LED Screen Panel Repair Guide B) LCD Panel: HT185WX1-100 TV/Monitor: Lenovo L1961WC LCD Monitor Symptom: Monitor White Screen, Washed Out Picture, Display Slow Motion and Full Screen of Horizontal Thin Lines. This LCD Monitor after power on, it is white screen, after several seconds change to wash out picture and display slow motion. This LCD Monitor screen also full of thin horizontal lines. As usual, first step is to measure their VGH and VGL voltage on T-con board. Found all voltages looks normal, the VGH is 27V and VGL is -5V. Next step is to testing the Gate Driver Y-TAB film point’s voltages. Can’t any VGH voltage there and this part number of TAB is not available in the TAB Bypass List. So use a resistor to find out which is the VGH voltage point now. Finally found that VGH point and solder a copper wire to this TAB point and another side of wire will solder on T-con VGH point. This LCD Monitor is working perfectly now.

LCD/LED Screen Panel Repair Guide Note: From the previous experience that LCD Panel top corner of X1 (X-TAB) and Y1(Y-TAB IC) their circuit lines (ITO) easily circuit break on this area. Second is the X1 ACF contact pins dry joint occur there. That’s why the TAB Bypass Modification most of the time is connects from Y1 to X-Board (Source PCB). Another tips is, X1 and Y1 is the top failure rate of COF IC in LCD Panel. Because these two IC is responsible for the supply voltage like VGH, VGL and DVDD go through it.

(B) T-con Board: 6870C-4000H LCD Panel: LG LC320WUF SBN1, LC420WUF SBA1, LC420WUFSBB1, LC420WUD SBA1, LC470WUF SBN1, LC550WUD SBA1 Desc: LC320/420/470/550WU_120Hz

LCD/LED Screen Panel Repair Guide When the TV display is upside down problem or display is in wrong/abnormal position, try to remove R205 to R202. If your T-con board R205 location is empty and R202 is present the resistor there, just removed the R202 resistor to R205 position (exchanged). If the above methods also not solve the problem, then you can try to remove both R202 & R205 resistors and give it a try. If still the same problems then try to put both R202 & R205 with same spec resistor and try it again.

LCD/LED Screen Panel Repair Guide Mainboard firmware is not match/compatible with their Panel. Or the T-con board is not match/compatible with the Panel. 1) When the LCD/LED TV complaint problem is about display upside down symptom but without replace any PCB board inside the TV: Normally this symptom is causing by their Mainboard setting or their memory IC firmware was abnormal. Or their T-con board EEPROM memory data was abnormal. With this type of symptom, first thing to do is login to their Factory Setting to do the adjustment for their display. If still not help, we can try to update their firmware into the Mainboard or re-programmed their EEPROM data to the T-con board. But both methods you need to get the correct model, same version and working firmware to do it with ISP Programmer. If not, you can try to use the “Display Rotation Method” above to repair it. * If the Mainboard and T-con board firmware after updated also same problem, then you should check the R202 or R205 SMD resistor for bad solder point or dry join.

2) After replaced Mainboard, the display position was changed to abnormal position: This type of display problem was because of Mainboard model number is same but their firmware version is not correct and not match with their current TV Tcon board (Panel). Because some of the TV manufacturer, their Mainboard can using in different TV model and TV sizes. So their different is just the firmware version inside the flash memory. With this type of problem, we need to find their correct firmware version and using the ISP Programmer to programming their memory IC. For the branded TV, it is hard to get their invert (upside down) version firmware. If that’s the Universal Mainboard, they will provide the firmware to choose. 3) After replaced a LCD/LED Panel, the display is upside down: Some LCD/LED Tv their T-con board location was on the top of the Panel. But some of the T-con board location was on the bottom of Panel. So when the LCD/LED Panel is broken and need to replace with a different model & brands Panel, we need to do some modify to it. For example to find a long LVDS cable

LCD/LED Screen Panel Repair Guide to fit in new LCD Panel. Or rotate LCD Panel to fit in old TV cover/holder. So the TV repairer if using the above method also can’t solve the problem, so they can try to manually rotate that LCD Panel and modify their cable/s. Even this is a stupid method, but I saw some of the repairer they also using this method to solve their display upside down problem! 

This LCD Panel was replaced a new T-con strip (this T-con board was attached with the Panel) with the TAB Bonding Machine. But the display is upside down. Normally this problem can solve by changing their mainboard firmware (upside down type) or login to the Service Menu to adjust their Mirror mode. Because of didn’t have the upside down type firmware for their mainboard and the Service Menu also didn’t have the Mirror mode, so will try other method to repair it.

This Sharp LCD Panel has a common fault of display left half and right half was reversed. Please refer to the photos above. This TV even re-programming their Mainboard firmware also can’t solve the problem. So confirm the problem was in the T-con board there. But this part number of T-con board EEPROM firmware is not available. So it is hard to repair it or maybe need to replace a new or working T-con board to give it a try. http://www.LCDRepairGuide.com/Screen-Repair/

LCD/LED Screen Panel Repair Guide Fortunately found this model of T-con board (Panel) has a common fault of this symptom. And the manufacturer also created the solution or service bulletin to repair this T-con board. The method is easy just solder a wire to shorted the smd inductor nearby the LVDS connector. Please refer to the photos below. After that this TV display problem solved!

White Screen Problem on V315B3-C04 T-con Board T-con Board: V315B3-C04 Panel Model: V315B3-L04 This T-con board has using in lots of brands and model LCD Tv, for example Sony, Hisense, Konka and etc.

This LCD Panel V315B3-L04 has a common fault that is “White Screen’ problem. This is because of the V315B3-C04 T-con Q2 (A18E, P-channel MOS) was shorted. When this LCD Panel with white screen problem measures their VAAP (or calls it as VDA) is 0V. Power of the TV, using Ohm meter to measure the VAAP point to GND is about 2 ohm only! That’s mean some of the VAAP circuit component/s is shorted. After checking VAAP circuit found the Q2 was short circuit. Remember! Please don’t direct replace the Q2 and power on the TV. Because it maybe will short or burn the Q2 or maybe take some time it will come back again with the same symptom. This is because of their LCD Pane l design bug! Their Source PCB and above metal shield not put an isolated pad in between

LCD/LED Screen Panel Repair Guide them. So it will easily Source PCB components touch the metal shield and shorted T-con board. So insert a thin plastic pad or any insulated material to isolate the Source PCB and their above metal shield. Remember to put insulated of both left and right side Source PCB. After modify, this LCD Panel can last long to use.

No Display or Grey Screen - Common Fault on LG 370WX4-SLA1_(6870C-0158A) Panel: LG 370WX4-SLA1 T-con Board: 6870C-0158A Symptom: No display or grey screen (no display but backlight lit)

A 47 inches LCD TV came with complaint no display problem. After power on the TV, TV sound ok and backlight lit. So suspect the T-con board problem. After checked the T-con, found their VGH voltage abnormal just about 2V only.

How to Solve Samsung LCD TV Oil Painting Display Problem The customer bought in a LCD TV with the symptom like display oil painting. You can refer to the photo below:

This LCD TV didn’t have any logo in front of the TV cover and the rear cover also no any tv manufacturer details or the model too. But the customer said it is a Samsung LCD TV. After dismantle this LCD TV, their PCBs are use as photo below:

LCD/LED Screen Panel Repair Guide This LCD TV is using a Universal LCD/LED TV Mainboard, not the Samsung mainboard as usual we look inside the Samsung Tv. This mainboard part number is: VS.T811_V2.1. The photo of this universal mainboard:

This universal mainboard was using in many OEM brands LCD & LED TV. But this mainboard has a common fault it was the symptom of “Oily Painting Display” problem or Display Distortion problem on the screen.

Normally this symptom was causing by the TV Panel setting problem. Because of this universal mainboard(VS.T811_V2.1) can support several model panels for LCD/LED TV, so it has panel setting inside their Factory Setting. Use the Universal Mainboard TV remote control and press the “SOURCE” button, after that press buttons 2, 0, 8 (within 3 seconds) and it will show the Factory Setting page on the screen.

Choose the “Panel Adjust” button, inside there to select “Ti Map 10 Bit T-=1”. Exit the factory setting and restart the TV. The TV is back to normal now.

How to Repair LCD TV Symptom with Blue Screen and Vertical Bars Brand: Hisense TLM-3233D LCD TV Symptom: No Display but Blue Screen with Two Vertical White Bars

When power on this lcd tv, the screen show no display but blue screen with two vertical white bars. The two vertical white bars will flash but no any content inside. The LCD TV can hear the sound and remote control to change channel properly. Try other video signals input like AV and PC also same results. Even try to call out the OSD menu also same problem too. Since the LCD TV cannot show the OSD menu and the TV got sound and change channel properly, so that the mainboard is normal. After observation this lcd tv, found that the problem could be in the T-CON board or LCD panel. Check LVDS and FPC cables, they are show as normal, then check the T-CON board voltages. All voltages in T-CON board are ok, so that i will suspect the TCON board mainchip (N39) or their memory chip (N31) defective. I got the junk T-CON board with same part number, but their DC-DC chip was burnt. So the mainchip and memory IC can be use.

Because of the N39 (CM2681) have many pins and the memory IC N31 (24LC128) only have 8 pins, so that I choose to replace the N31 first. After replace the N31, I try to power on the TV, and it was show display perfectly! Since this N31 is a memory IC, does that mean IC itself damage or just the firmware corrupt and caused this problem happen? To find out this answer, I use my programmer to copy the working memory IC firmware and write it into the original memory IC. Do you guess what has happen? Yes, the LCD TV working perfectly too! So the problem solved and it was causing by the firmware corrupted. The T-CON board memory chip or their firmware corrupt also can cause the screen problem. So that we need to save their firmware and must prepare some junk boards of T-con board, mainboard and inverter board for future use.

How to Repair the Display Washed Out Screen Problem Model: Samsung LA-37A550P1RXXM LCD TV LCD Panel: T370HW02 V.4 T-Con Board: T370HW02 When power on the tv, the screen is normal. But after about 10 seconds, it becomes blurring or nearly white screen/washed out. Like the picture below:

From the previous experience it is the T-con board problem. As usual, first check their T-con board top 5 voltages and other related voltages: Vcc input= 11.63V VGH= 27.01V VGHC= 25.89V http://www.LCDRepairGuide.com/Screen-Repair/

How to Easily Remove AS-15F IC without 3 Minutes Here has a question, how to remove this AS-15F spider IC easily? Because lots of the repairer facing a problem is hardly to remove this IC even using their soldering reworks station! This method you just need to use a utility knife and a normal soldering iron can easily remove this IC! Yes, within