signs of a bad lcd panel made in china

Vin: PWB input voltage (12V)VDD: ASIC, source IC, gate IC driving power (3.3v)VGH: TFT component switching voltage (~30V)VGL: TFT component turn-off voltage (~ -6v)VAA: step control voltage (~17V)VCOM: liquid crystal reversal reference voltage (~7V)

3. #If all the above is OK, measure the LVDS voltage value. Under normal conditions, the LVDS signal’s RX+/ RX-voltage value is about 1.2v, and RX+/ RX-difference value is about 200mV. At the same time, the resistance of the LVDS signal to ground and the resistance between the LVDS signal pairs can be measured (100 ohms). If there is an exception to these values, try replacing the ASIC.

1. #Confirm whether the COF on side X is hot compared with the normal temperature, whether there is fracture or wear crack, and whether the COF is burnt.

2. #Confirm whether the VAA is normal (normally about 17V). If abnormal, disconnect the RP32 to confirm whether it is caused by DC/DC loop or X-side COF: disconnect RP32, if the VAA is normal, the COF is bad, CO must be changed; COF can be Disconnect one by one to determine which NG disconnects RP32, VAA NG, try to change UP1; at the same time, confirm whether the continuity of the surrounding triode is OK.

4. #Determine whether the gate IC is OK. There is a signal test point on the back of COG-IC, and the green paint can be scraped for measurement confirmation; If there is a gate IC problem, which IC fault can be confirmed. The confirmation of gate IC fault is only for analysis when you are interested, and this method is not recommended.

1. #Measure GM1~GM14, the values are arranged from large to small. In general, a certain gamma value will be abnormal in the case of NG, then try to replace gamma-IC;

3. #Confirm whether the RSDS value is correct, normal RSDS is about 1.2v, and the signal difference is about 200mV; At the same time, we can confirm the resistance between RSDS signal (normal 100 or 50 ohms) and RSDS resistance to ground. If the voltage is NG, check if the ASIC and X-COF are hot.

Polarizer / CELL damaged To change the polarizer, a polarizer attaching machine is required The degree of whitening of the picture changes with different viewing angles

1. #Adjust the VR knob to see whether it can be adjusted and whether the screen performance changes. At the same time, confirm the VCOM value (about 7v), if NG, replace the VR knob.

2. #Confirm VGH/VGL voltage (about 30V VGH and -6v VGL), and confirm whether it is DC/DC loop NG or COF IC NG; The corresponding resistance of disconnected VGH and VGL can determine whether it is a DC/DC problem or a COF-IC problem. If it is DC/DC NG, try to replace UP1 or confirm whether the corresponding transistor is OK.

3. #If the whiteness changes significantly with the view Angle, and above 1&2 analysis is all OK, polarizer NG or CELL NG can be basically determined.

3. #Confirm whether the gate IC is OK. There is a signal test point on the back of COG IC, which can scrape the green paint for measurement confirmation; Or cut COF halfway from G3. If there is a gate-ic problem, which IC fault can be confirmed.

2. #Confirm whether there is 12V input, if not, confirm whether the connector is OK, and confirm the resistance value of 12V voltage to earth; If conn. NG, change conn.; If 12V is short-circuited to the ground, disconnect FP1 to determine the short-circuiting circuit.

3. #Confirm whether FP1 is open; if open, replaces fuse. If the 12V accessory of this model has a reverse diode, confirm the continuity of the diode and check whether it is burnt.

B. Confirm VAA resistance to ground at VAA test point of R plate (A short circuit usually occurs), disconnect the corresponding capacitance of the following 3 COF, and confirm VAA resistance to the ground again. If OK, replace the capacitor, if NG, replace COF. If VAA is still NG, confirm DC/DC loop as all models.

6. #Disconnect RP32 to confirm VAA, if NG, try to change the PWM IC (in general, it will be good), if still NG, try to change the gamma-ic or corresponding to the VAA several large capacitances (in general, it is rare, this situation is generally accompanied by VAA to the ground short circuit).

3. #Shaking module, if vertical lines disappear or reappear, then it can be judged that the possible cause is COF pin broken, and the crease should be found under the OM microscope.

4. #Press the LCD glass side of the panel, if the vertical lines disappear or reappear, it can be judged that the cause of poor contact, OM checking should be able to find the poor contact.

5. #If there is no display change in pressing, confirm whether ITO is damaged under the OM microscope, or pin signal waveform corresponding to needle COF.

Lamp line is broken Replace the lamp tubing Depending on the backlight structure, there will be different results. The failure of the performance may be a point-off, or it may be a backlight with a dark band.

4. #The above disassembly judgment can basically solve the problems of point-off in the market. If you can’t tell the truth, you can directly change the lamp tube.

Lamp line is broken Reconnect / replace lamp tubing Depending on the protection status of the power board, it may be a backlight with a dark band or it may be a point-off.

3. #Disassemble the backlight, confirm whether there is a short circuit with broken skin on the lamp strip, whether the plug of the lamp strip is fully integrated with the socket, whether the pin is aslant/off, whether the connector is off, and whether the LED bead is black and injured.

4. #The fault of the product is basically caused by the above reasons. If the appearance is fault-free, the lamp bar can be crossed to confirm whether the phenomenon follows the lamp bar, or the voltage of the lamp bar and the conduction condition between the lamp beads can be measured.

The above is the full text of LCD screen failure repair guide, we hope it is helpful to you. If you need to buy LCD and find a reliable LCD supplier, we suggest you to read our other great blog – How to find a reliable LCD supplier.

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The difference between a LED TV and a LCD TV is that they are both LCD TV’s except one has LED stripes and the other has CCFL Backlights- (Florescent Tubes). I used a Philips Magnavox Emerson LG TV when testing these repaird, but they should work on other TV brands that are similar. Before you do any Repair, check to see if you are still under warranty, or are covered by a recall of your TV!!

Unplug the cable between power board and the main board. If the back-light turns on it means that power board is working and the problem is with the main board

If your Plasma or LCD/LED or CCFL/LCD TV or monitor has stopped working, or is displaying one of the following symptoms, then it *may* need some new capacitors in the power supply board or a replacement board

Unplug the cable between power board and the main board. If the back-light turns on it means that power board is working and the problem is with the main board

-Upon three unsuccessful start up attempts the TV locks itself in protection mode and needs to be disconnected from AC for 30-40 seconds before power attempts can be restore-Display Locks after 10 minutes–

1) the front green LED of your TV comes and stays on for 20-30 seconds, then turns off for 1-2 seconds and then keeps cycling like that, but the display never comes;

2) the display comes on for a brief few seconds, then the TV shuts off; in some models the display may not even come on, but still the relay clicking on and off and the green power LED activation and shutdown can be easily observed.

Look at the screen. If you see a blank screen with a red key on the bottom of the screen, press FUNCTION and MUTE at the same time. This will unlock the channel

A model number is needed to determine the unlock procedure, but most likely you will need a remote to unlock most TV’s. Below is a common lock procedure.

Choose On to disable all the buttons on the front of the TV. FPA Lock On will appear on the TV screen each time you press buttons on the front of the TV. You can still operate the TV with the remote control. You can still use the POWER button on the front of the TV, but only to turn off the TV (not on). Set FPA Lock to Off to cancel this feature so you can use the buttons on the front of the TV again.

3. Press and hold each of the remaining buttons on the TV, one at a time, for about five seconds, and then release. DO NOT use the buttons on the remote control - only use the buttons on the TV itself.

6. The TV should start automatically scanning for active channels from your input signal source. Make sure you have a good signal (antenna or cable or satellite).

If the TV still does not display anything, try the menu button on the TV and see if you can access the menu. If not, try using the remote control’s menu button.

If the TV is still locked and will not respond to any commands from the front panel control buttons or the remote control unit, it is apparently locked in a failure or diagnostic mode, and would probably have to be diagnosed and repaired by a reputable TV repair facility. Good luck.

If it is a thin vertical line that appears on certain video resolution/image then it is normal and is indicated in the users manual under troubleshooting. If the line is almost half the screen, it could be a problem with the cable connection between the LCD panel and logic board, or the LCD panel itself. Try reseating the cable first if it’ll solve the problem. I’ve done similar issue in the past. Reseating the cable worked for a couple of months till eventually the LCD panel is the problem. Replacing the LCD panel is quite costly and impractical.

If the lines are there all the time or intermittent but in the same location it is an indication of a bad panel. The panel driver can also be the cause of this symptom.

If the lines/bars are across the OSD Menu, and all the video signal inputs also same result, that means the TV LCD Panel is defective Most of the time this symptom is caused by a bad LCD Panel 95%. You can try refitting LVDS Cable or replacing Main Board capacitors or replacing Main Board—5%

Bad news unfortunately, their are two possible causes for what you have described, one would be a fault with the picture drive pcb ( Power Control Board ), and the other is physical damage to the LCD cell matrix, (screen).

There’s videos on how to fix this. It has to do with putting foam, in between panel frame and screen, which applies pressure to solder joints, which then completes the circuit- Contact my10cents, for better explanation.

Big Black Bar on bottom of TV Screen– If the bar that appears in the bottom is showing the energy saving logo, HDMI, Dolby surround and pc mode capabilities look into your remote.

Is the OSD menu affected as well? If yes then possibility could be the LCD Panel or the t-con board. Since you have replaced the t-con board then possibility is the LCD panel. There could be also a possibility of mainboard where upgrading the firmware could restore the picture. If the OSD menu is not affected then the LCD panel is good.

If the lines are across the OSD menu then chances is very high the LCD panel is the cause of the problem otherwise it can be due to bad T-con board or even Mainboard. Have you tested on the OSD menu to see if the lines are really across the menu?

White Lines– There are several possibilities that can cause white lines on an lcd screen. One would be high temperature on the logic board. Logic board drives the LCD panel and when it overheats can cause this display problem. One solution would be to clean the vent holes around the TV. One possibility that I have experienced myself servicing is a bloated capacitor on the power supply board. The worst possibility is a defective LCD panel, which is costly to repair, and sometime more practical to buy a new TV set.

Do you get blue screen when using x-box or DVD, VCR? Have you tried to reset cable box if you have one? Reset TV. Check all cable connections? Try these first.

Do you use the Set top box for cable channels? If yes then try connecting through HDMI and see if you can see the TV. Also do you get blue screen when using x-box or DVD, VCR?

What made you decide to change the mainboard? I ask because if the MENU does not appear, then this indicates a problem elsewhere within the TV. Also, did you check for any swollen, or bulged capacitors on the power supply board?

There are several problems that could cause this problem. It could be the connection from the T-Con board to the panel, try wiggling these cables around and see if the picture comes up even for a second. The Mainboard or it’s cables are not the issue in my opinion. The isdsue is either going to be a bad capacitor, faulty output from the power supply to the T-Con board, a bad connection from T-Con to panel, or the T Con or the panel itself are faulty.

Basic things you can do is to check the connections. If you have a cable box, check the video connections. And while doing that, unplug the TV and the cable box from the AC outlet for it to reset. These are the most likely cause of a blue screen

Most of the new TVs display a blue screen when theres no signal for it to lock on. Try unplugging it for about 5-10 minutes and see if that clears up the problem. Why? Because they have microprocessors in em (computer chips) and just as like with any other operating system, they can hang up or crash. This isnt an uncommon problem with todays TV sets. Unplugging it for awhile resets the microprocessor (in other words, it causes it to re-boot when you plug it in again).-

It could be the connection from the T-Con board to the panel, try wiggling these cables around and see if the picture comes up even for a second. The Mainboard or it’s cables are not the issue in my opinion. This is due to either a bad capacitor, faulty output from the power supply to the T-Con board, a bad connection from T-Con to panel, or the T Con or the panel itself are fault. Also, it’s possible the A/V receiver’s Video On feature was turned off by an electrical surge or something else.Turn the Video feature back to On and suddenly that bad blue screen was gone.

Repair/Solution: Change the cable box to a fixed resolution. OR have the customer install the latest TV firmware which can be located at your TV Brand Customer Support

Your power board needs serious help–If you want to repair you have to replace Switching Mosfets, disc capacitors and of course the main fuse, Rectifier Diodes and most of the time the transformer–Costly–Easier to replace Power Board–There is a chance the strike come through the cable line, so it’s possible the Main Board needs repair–That’s a small chance though, but I thought I’d let you know–Replacing power board should repair your TV. During a lightning storm, electrical power surges is induced to the transmission line eventually end to our household appliances. Our TV sets, computers are the most susceptible. For the TV set, the basic cure is to leave the TV unplug from the AC outlet for it to discharge and reset

5. wait another 30 seconds and some type of picture should appear—If that does not work–Unplug TV for 10 minutes and then hold power button on TV for 60 seconds–Plug in and turn on.

Unplug TV– On TV, hold the power button down while pushing and holding each button for a few seconds. After going through all buttons, (on TV) then plug TV back in and it should power up–

When the TV, has no Picture or Sound. Led turns from red to (Blue or Green). It means the Main Board has sent out the start up signal to the PSU (Power Supply) Board.

Now we need to know if PSU Board has all the correct output voltages. This means checking the secondary side output voltages of Power Board. Probable causes are the Power Supply, the T-Con board, Main Board or the LCD panel itself has failed.

No Picture/Sound The person who looked at my TV, stated that the high voltage power supply needs to be replaced. He explained that I have a low voltage supply which is why the power button is lit once pressed, and a high voltage supply which needs to be replaced.

Solutions: If the unit tries to turn on but begins to cycle on and off before any video is displayed and all of the SMPS (Power Board ) voltages are good, disconnect the LVDS cable at the T-Con board

You will have to go into the TV and check for capacitors or burn marks or cracked solder around the pins–Main board could be IC’s, or regulators–Panel–Disconnect panel and see if your TV stay’s on—

The flashing green light indicates a fault on the power board inside your TV. This will be due to a faulty component like a capacitor or voltage regulator. Faulty electrolytic capacitors on the power board are the most common cause of this problem. These capacitors will often leak and stop working as the TV set gets older,but could also be caused by the Main Board or the inverter board. (LCD TV ONLY) So we will have to take a look inside and maybe do some circuit testing and a visual of your boards-

In a dark room take a flashlight and at an angle shine it on the screen and see if you can see any movement. If you can see movement or see your menu then its backlight failure. If totally black screen with sound then its T-Con board. So if you see movement on a led screen, then it’s your LEDs inside the panel. If on a LCD TV you see movement and lamps are not turning on, replace inverter. If with a LCD TV your lamps turn on, with no picture replace T-Con Board.

Plasma is the most durable in terms of panel failure. LED/LCD is terrible for panel failure. (But every model gets bad apples. Samsung LED/LCD panels die frequently. LG panels are a lot more reliable.) Overall I’d say plasma is more reliable, and even if it fails, in most cases plasma is repairable, LED/LCD is expensive to repair and often difficult to troubleshoot.

3)- Switches off for a second or two intermittently. Relay clicks and standby LED remains green. Switches off intermittently with green LED on, no sound or no picture.

A blurry image on a high-definition LCD TV is typically the result of a mismatch between the TVs resolution capabilities and the resolution of the signal that is coming from connected devices, such as a DVD player or satellite TV receiver. Typically, blurry pictures result when a peripheral device connects to the TV through non HD cables and jacks.

Troubleshooting CRTs versus LCDs begins with similar steps, but diverges due to the differing natures of the two display types. The first troubleshooting steps are similar for either display type: power down the system and display and then power them back up; make sure the power cable is connected and that the outlet has power; verify that the signal cable is connected firmly to both video adapter and display and that there are no bent pins; verify that the video adapter is configured properly for the display; try the problem display on a known-good system, or try a known-good display on the problem system; and so on. Once you"ve tried the "obvious" troubleshooting steps, if the problem persists, the next step you take depends on the type of display. The following sections cover basic troubleshooting for CRTs and LCDs.

CRTs seldom fail outright without obvious signs, such as a loud snap or a strong odor of burning electrical components. Most CRT problems are really problems with the power, video adapter, cable, or hardware/software settings. To eliminate the CRT as a possible cause, connect the suspect CRT to a known-good system, or connect a known-good display to the suspect system. It is worth noting, that older CRTs eventually wear out, and starts dimming. Common signs of a weak CRT are a dim picture, dysfunctional brightness and/or color controls, image smearing at high brightness, and in color CRTs, a tint towards a single color (Red Green Blue)

If the CRT is the problem, it is often not worth repairing. If the CRT is out of warranty, parts and labor may cost more than buying a new CRT, which also gives you better specs and a warranty. About the only CRTs we"d even consider repairing out-of-warranty are high-end 21" or larger models, and even there the economics are dubious.

Even if the CRT is in warranty, the shipping costs may exceed the value of the CRT. For example, shipping a CRT both ways can easily cost $75 or more. If that CRT is a year-old 17" model, you"re probably better off spending $100 to $200 for a new 17" or 19" CRT than paying $75 in shipping to have the old one repaired. CRTs have many components, all of which age together. Fixing one is no guarantee that another won"t fail shortly. In fact, that happens more often than not in our experience.

Never disassemble a CRT. At best, you may destroy the CRT. At worst, it may destroy you. Like televisions, CRTs use extremely high voltages internally, and have large capacitors that store that energy for days or even weeks after the CRT is unplugged. Robert once literally burned a screwdriver in half when working inside a color television that had been unplugged for several days. Also, the large, fragile tube may implode, scattering glass fragments like a hand grenade. People who repair CRTs and televisions for a living treat them with great respect, and so should you. If you must repair a CRT, take it to someone who knows what they are doing. You have been warned.

Check the obvious things first. Verify that the CRT is plugged in (and that the receptacle has power), the video cable is connected to the video card, the computer and CRT are turned on, and the brightness and contrast settings are set to the middle of their range. If none of these steps solves the problem, your CRT, video card, or video cable may be bad. Check the suspect CRT on a known-good system or a known-good CRT on the problem system.

CRTs contain multiple filaments, which can be broken, or gas may have leaked into the vacuum inside the CRT. CRTs damaged this way are unrepairable without specialist equipment. With the display open. check if all three filaments are glowing bright orange. Excessive redness or purple arcing signifies gas has leaked in. There may also be an internal short inside the CRT, which is also unfixable without specialist equipment.

If you have ACPI or APM power management enabled, it may be causing the problem. Some systems simply refuse to wake up once power management puts them to sleep. We have seen such systems survive a hardware reset without restoring power to the CRT. To verify this problem, turn off power to the system and CRT and then turn them back on. If the CRT then displays an image, check the power management settings in your BIOS and operating system and disable them if necessary.

The horizontal and/or vertical deflection system has failed. The CRT tube itself is fine, but the circuitry driving the tube has failed. Replace the display.

This is a hardware problem with one of the electron guns. Replace the CRT. This problem may also manifest as a strong color cast during normal operation that is not correctable using the normal color balance controls.

Catastrophic CRT failure is imminent. The noises are caused by high-voltage arcing, and the smell is caused by burning insulation. Unplug the CRT from the wall before it catches fire, literally.

There are two likely causes. First, you may be driving the CRT beyond its design limits. Some CRTs display a usable image at resolutions and/or refresh rates higher than they are designed to use, but under such abuse the expected life of the CRT is shortened dramatically, perhaps to minutes. To correct this problem, change video settings to values that are within the CRT"s design specifications. Second, the power receptacle may be supplying voltage lower than the CRT requires. To correct this problem, connect the CRT to a different circuit or to a UPS or power conditioner that supplies standard voltage regardless of input voltage.

This is usually a minor hardware problem. The most likely cause is that the signal cable is not connected tightly to the CRT and/or video card, causing some pins to make contact intermittently or not at all. Verify that no pins are loose, bent, or missing on the cable or the connectors on the CRT and video card, and then tighten the cable at both ends, If that doesn"t fix the problem, open the computer, remove the video card, and reseat it fully.

In elderly systems, another possible cause is that some hardware DVD decoder cards "steal" one color (usually magenta) and use it to map the DVD video signal onto the standard video signal. Remove the DVD decoder card. If your video adapter includes hardware DVD support, or if you are upgrading to such an adapter, you don"t need a DVD decoder card.

The most likely cause is that the CRT is receiving inadequate power. Connect it to a different circuit or to a backup power supply that provides correct voltage regardless of fluctuations in mains voltage.

The most likely cause is that the refresh rate is set too low. Change the refresh rate to at least 75 Hz. Flicker also results from interaction with fluorescent lights, which operate on 60 Hz AC and can heterodyne visually with the CRT. This can occur at 60 Hz (which is far too low a refresh rate anyway), but can also occur at 120 Hz. If you"re running at 120 Hz refresh and experience flicker, either use incandescent lighting or reset the refresh rate to something other than 120 Hz.

The video card settings are likely outside the range supported by the CRT, particularly if you have just installed the CRT or have just changed video settings. To verify this, restart the system in Safe Mode (press F8 during boot to display the Windows boot menu and choose Safe Mode). If the system displays a VGA image properly, change your display settings to something supported by the CRT.

Most modern CRTs can display signals at many different scan frequencies, but this doesn"t mean that the CRT will necessarily automatically display different signals full-screen and properly aligned. Use the CRT controls to adjust the size and alignment of the image.

Depending on the CRT, video card, and video settings, this may be normal behavior, adjustable using the CRT controls. If the distortion is beyond the ability of the controls to correct, the problem may be with the video card, the CRT, or the driver. First try changing video settings. If the problem persists at several settings, move that CRT to a different system (or use a different video card) to determine whether the problem is caused by the CRT or video card. Repair or replace the faulty component.

This is usually caused by RF interference from another electrical or electronic device, particularly one that contains a motor. Make sure such devices are at least three feet from the CRT. Note that such interference can sometimes penetrate typical residential and office walls, so if the CRT is close to a wall, check the other side. Such image problems can also be caused by interference carried by the power line or by voltage variations in the AC power supply. To eliminate interference, plug the CRT into a surge protector. Better still, plug it into a UPS or power conditioner that supplies clean power at a constant voltage.

This problem may also be caused by using a video cable that is too long or of poor quality or by using a poor-quality KVM switch (keyboard/video/mouse switch). Manual KVM switches are particularly problematic.

The CRT may need to be degaussed. A CRT that sits in one position for months or years can be affected even by the earth"s very weak magnetic field, causing distortion and other display problems. Exposing a CRT to a strong magnetic field, such as unshielded speakers, can cause more extreme image problems. Many modern CRTs degauss themselves automatically each time you cycle the power, but some have a manual degauss button that you must remember to use. If your CRT has a manual degauss button, use it every month or two. The degaussing circuitry in some CRTs has limited power. We have seen CRTs that were accidentally exposed to strong magnetic fields, resulting in a badly distorted image. Built-in degaussing did little or nothing. In that case, you can sometimes fix the problem by using a separate degaussing coil, available at RadioShack and similar stores for a few dollars. We have, however, seen CRTs that were so badly "magnet burned" that even a standalone degaussing coil could not completely eliminate the problem. The moral is to keep magnets away from your CRT, including those in speakers that are not video-shielded.

An incorrect yoke may have been attached to the CRT. Unless you have a lot of spare time on your hands, this is usually not worth fixing. Replace the display.

You may have a weak picture tube. Without specialist equipment, this is usually unfixable. You could try a CRT rejuvenator as a last resort, but this may fix or kill your CRT permanently.

If your LCD displays no image at all and you are certain that it is receiving power and video signal, first adjust the brightness and contrast settings to higher values. If that doesn"t work, turn off the system and LCD, disconnect the LCD signal cable from the computer, and turn on the LCD by itself. It should display some sort of initialization screen, if only perhaps a "No video signal" message. If nothing lights up and no message is displayed, contact technical support for your LCD manufacturer. If your LCD supports multiple inputs, you may need to press a button to cycle through the inputs and set it to the correct one.

Unlike CRTs, where increasing the refresh rate always reduces flicker, LCDs have an optimal refresh rate that may be lower than the highest refresh rate supported. For example, a 17" LCD operating in analog mode may support 60 Hz and 75 Hz refresh. Although it sounds counterintuitive to anyone whose experience has been with CRTs, reducing the refresh rate from 75 Hz to 60 Hz may improve image stability. Check the manual to determine the optimum refresh rate for your LCD, and set your video adapter to use that rate.

First, try setting the optimal refresh rate as described above. If that doesn"t solve the problem and you are using an analog interface, there are several possible causes, most of which are due to poor synchronization between the video adapter clock and the display clock, or to phase problems. If your LCD has an auto-adjust, auto-setup, or auto-synchronize option, try using that first. If not, try adjusting the phase and/or clock settings manually until you have a usable image. If you are using an extension or longer than standard video cable, try connecting the standard video cable that was supplied with the display. Long analog video cables exacerbate sync problems. Also, if you are using a KVM switch, particularly a manual model, try instead connecting the LCD directly to the video adapter. Many LCDs are difficult or impossible to synchronize if you use a KVM switch. If you are unable to achieve proper synchronization, try connecting the LCD to a different computer. If you are unable to achieve synchronization on the second computer, the LCD may be defective. Finally, note that some models of video adapter simply don"t function well with some models of LCD.

If the screen is displaying a full, stable image, but that image is of poor quality, first verify that the display is not connected through a KVM switch or using an extension cable. If so, connect the display directly to the video adapter using the standard cable. If that is already the case, adjust the brightness, contrast, and focus controls. If you are unable to get a proper image using these controls, the problem is most likely a clock or phase mismatch, which you can cure by taking the steps described in the preceding item.

The best way to adjust clock and phase is to use auto-adjust first. Check the utility and driver CD that came with the monitor. It may have a wizard or at least the appropriate background screens to use while adjusting phase and clock settings. If not, go to the Windows Start menu and select Shutdown. When the screen goes gray and the Windows Shutdown dialog appears, leave that dialog onscreen, but ignore it. Use the gray screen to adjust clock and phase manually. Any problems with clock and phase and any changes you make to the clock and phase settings are clearly evident on the gray screen.

Always adjust clock first. Clock is usually not a problem if you have used the auto-adjust feature of your monitor, but if you do have clock problems they will be evident as large vertical bars on your screen. Tweak the clock setting until those bars disappear. Then adjust phase. Phase problems are evident as thin black lines running horizontally across the screen. Adjust phase until the lines disappear or are minimized.

Not all analog video cards synchronize perfectly with flat panels. The gray Shutdown screen exaggerates the problem, so don"t worry if very tiny movements are visible after you"ve adjusted clock and phase as well as possible. After you"ve set the clock and phase controls for the best image possible on the gray screen, cancel Shutdown and the image should be optimized.

Your video card is supplying a video signal at a bandwidth that is above or below the ability of your LCD to display. Reset your video parameters to be within the range supported by the LCD. If necessary, temporarily connect a different display or start Windows in Safe Mode and choose standard VGA in order to change video settings.

This occurs when you run an LCD at other than its native resolution. For example, if you have a 19" LCD with native 1280x1024 resolution but have your display adapter set to 1024x768, your LCD attempts to display those 1024x768 pixels at full screen size, which physically corresponds to 1280x1024 pixels. The pixel extrapolation needed to fill the screen with the smaller image results in artifacts such as blocky or poorly rendered text, jaggy lines, and so on. Either set your video adapter to display the native resolution of the LCD, or set your LCD to display the lower-resolution image without stretching the display (a feature sometimes referred to as display expansion), so that pixels are displayed 1:1, which results in the lower resolution using less than the entire screen.

This is a characteristic of LCDs, particularly older and inexpensive models, caused by defective pixels. Manufacturers set a threshold number below which they consider a display acceptable. That number varies with the manufacturer, the model, and the size of the display, but is typically in the range of 5 to 10 pixels. (Better LCDs nowadays usually have zero dead pixels.) Nothing can be done to fix defective pixels. Manufacturers will not replace LCDs under warranty unless the number of defective pixels exceeds the threshold number.

Some people claim that leaving the unit powered off for a day or two will "erase" a persistent after-image. Others suggest leaving a neutral gray screen (like the one used for phase adjustment) up on the screen to "equalize" the display. I dunno. FWIW, I"ve seen this problem on older Samsung panels but never on the Sony or NEC/LaCie panels I use.

Again, this is a characteristic of LCDs, particularly older and inexpensive models. The after-image occurs when the display has had the same image in one place for a long time. The after-image may persist even after you turn the display off.

Transistor-based pixels in an LCD respond more slowly than the phosphors in a CRT. The least-expensive LCDs exhibit this problem even with slow image movement, as when you drag a window. Better LCDs handle moderately fast image movement without ghosting, but exhibit the problem on fast-motion video. The best LCDs handle even fast-motion video and 3D gaming very well. The only solution to this problem is to upgrade to an LCD with faster response time.

Use the brightness control to increase image brightness. If you have set brightness to maximum and the image is still too dim, contact the display manufacturer. The CCRTs used to backlight the screen have a finite lifetime and may begin to dim as they near the end of their life.

If one or more horizontal and/or vertical lines appear on the display, first power-reset the computer and display. If the lines persist, run the auto-setup function of your display. If that does not solve the problem, power the system and display down, remove the video cable, and verify that the video plugs and jacks on both computer and display ends do not have broken or bent pins. Even if all appears correct, try a different video cable. If the problem persists, contact the display manufacturer.

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“Original” screens are those containing LCDs manufactured for Apple. “Copy” screens are compatible replacements entirely designed and manufactured by third-party companies not associated with Apple.

LCD display panel can have poorer resolution (i.e. looks “coarser”), worse brightness, contrast and vibrancy and reduced refresh rate amongst other problems.

Changes in specification from original can result in battery and performance issues. Certain badly-engineered screens could even damage the backlight circuitry.

Customers who bring their iPhones to us for a screen repair are offered two choices of replacement- an original or a “copy” screen. The most common response is “Is there a difference- and which one would you recommend?”

Originals are those screens containing LCDs that were manufactured for Apple. So-called “copy” screens are compatible replacements, but designed and manufactured entirely independently by third-party companies, typically in China.

Our answer is simple- the original screen is the one we’d go for ourselves, every time. Some people think we make more money on them, but this isn’t the case. We recommend originals because they’re far higher quality and the price difference is fairly small.

We’d rather only fit original screens. The only reason we don’t is that many people will shop around and choose purely on price. As such, we need to offer the cheaper copy screens to remain competitive and avoid losing these customers. In some cases, they didn’t even know there was a difference in the first place- especially since it’s not in some shops’ interest to draw people’s attention to the issue!

This may well be the worst copy screen we’ve ever come across. As a result, the unfortunate customer has ended up paying twice to have their screen replaced- we’re sure that had they been properly informed, they would have chosen an original in the first place.

While the difference in price between copies and originals can vary across devices, it’s generally around £10 – £14 extra to have an original screen fitted. This really isn’t a lot considering the improved quality and reliability.

We compare our prices to our competitors- and we know that we come out of it favourably. While we have to offer copy screens to remain competitive, we always advise customers to go for the original.

When you’ve spent- directly or indirectly- several hundred pounds for an iPhone with a Retina display, it doesn’t make sense to replace it with a lower-quality screen that can make a £400 phone look like a £40 one! Not only that, but you’re likely to have fewer issues, and a longer-lasting screen.

There’s nothing stopping any random person without training or experience opening up a smartphone repair shop. As a result, the industry is full of companies with little skill or experience who are only interested in getting hold of your money and installing the cheapest parts they can find.

Many- if not most- don’t even acknowledge the existence of copy screens, let alone explain the difference to the customer. Hardly in their interest to do so if they only fit cheap, low-quality copies. Some of them can hardly be blamed- they know so little, they’re not even clear on the differences between OEM, non-OEM and copy displays themselves! Others can be more deliberately misleading… and some outright lie.

Generally, these shops are looking for the cheapest price on replacement screens.. When offered a copy at a half or a third of a price of the original, they’re going to go for that. That might be fine if they offered the customer a cheaper price- what we disagree with is selling “supermarket beans” (i.e. the copy screens) at “Heinz beans” prices!

Heading towards the “blatantly fraudulent”, we’re aware of companies that shamelessly fit copy screens while claiming them to be original. Worse, they’ll take your broken original screen and sell that to a recycler for more than they paid for your copy!

Obtained or manufactured “off the clock” via the same production line that produced them for Apple- in some cases, from the stockpile of parts that didn’t meet Apple’s standards, or

Apple tightened up their supply chain around 2015, which reduced the number of screens available for repairs and increased their price dramatically. A lot of companies went bankrupt, and Chinese manufacturers responded by making their own “copy” screens from scratch. At first, these weren’t much cheaper than the Apple ones, but the price soon fell.

We should be clear that- despite the name- “copy” screens aren’t direct copies of the Apple originals. Rather, they’re compatible replacements that have been designed from scratch and- as a result- vary in some respects that have an effect on usability and quality.

One of the most important differences between an original and a “copy” screen is how the digitizer (touch sensor) is designed. Apple has it manufactured as part of the LCD itself, whereas the copies have it on the glass.

Although there are only a small number of manufacturers of the bare LCDs themselves, these are then bought by countless other companies who add the remaining components needed to turn these into a complete working screen. As a result, you could easily end up with an LCD from the best “copy” manufacturer, but the digitizer/touch (as part of the separately-manufactured glass) from the worst.

There are countless digitizers out there, and you can only take the supplier’s word that the quality is good. Many ship good ones at first, then switch to cheaper parts to make more profit. This is particularly bad with the iPhone 6S and 6S+, since Apple moved the chips responsible for touch processing onto the LCD itself. As a result, you’re not just getting a copy screen- you’re getting copy chips too.

The performance specification (power drain, etc.) of most copy screens isn’t identical to the originals. As a result, they can drain the battery more quickly and mislead the operating system which was optimised for the original screen design.

It’s even possible that this mismatch could damage your backlight. We do a lot of subcontracted repairs for less-experienced shops, and get backlight repairs in almost every day. We’ve had cases where we fixed the circuit, fitted the new copy screen to test it, and had it break the circuit again!

Copy screens can disrupt the touch ID fingerprint reader. With the 6S, 6S+, 7 and 7+, the home button- part of the 3D touch- is part of the screen assembly. Frequently the home button flexes on aftermarket designs don’t work properly and stop the touch ID working- annoying if you use it to unlock the phone or log in to your bank.

We’ve seen many lift away from the frame that holds them in place. This usually results in the flex cable getting torn, and the screen needing replacing. You don’t even need to have dropped the phone- this often happens through general everyday wear and tear.

That brings us to another major issue with the copies. When you drop an Apple original, the glass often breaks, but if the LCD itself is intact, you can continue to use it until it’s fixed. With the copies, the touch/digitizer is on the glass and stops working when that’s broken. Even worse, the LCD itself is more likely to break due to the thinner and more fragile glass.

We’re not convinced this will happen, since Apple recently changed their repair policy to accept iPhones with third-party screens. However, it is possible that copy screens could be stopped from working via an iOS update, since those make a number of security checks.

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Ever had your TV showing nothing but a black screen even if the audio was working? Unfortunately, that’s a common issue with low/middle-end LCD/LED TVs these days… Even more frustrating, this issue often comes from a rather tiny and cheap component that can be easily replaced. Most common issues are:

One of my relatives had this exact symptom happening all of a sudden. This problem on low-end TVs often occurs within the first couple years. As the repair costs for that kind of TV is pretty low, considering repairing it yourself might be a good idea!

The first step into repair is to find the root cause of the issue. As backlight failure is a very common issue, this is the first thing to test. To do so, the easiest way is to power on your screen, put a flashlight very close to it and check if you can see the image through. The image would be very dark, like turning the brightness of the screen very very low.

That implies disassembling the TV to access the backlight which is between the LCD screen in the front and the boards in the rear. In my case, with a Samsung F5000, I had to process as follows:

First we have to remove the back housing to reveal the boards (from left to right: main board, T-CON, power supply) and disconnect the LCD panel from the T-CON board.

Note: Older TVs have neon tubes for backlight, which is thicker and less exposed to this kind of failure. LED backlight is the most common thing these days, but do not mistake an LED TV with an OLED TV. The first one is a classic LCD panel with a LED backlight, whereas the second is an OLED panel that doesn’t need any backlight as it is integrated in each pixels (making the spare parts much more expensive by the way).

As we can see, the backlight system is made of 5 LED strips. First thing to do is look for burnt LEDs. Most LED backlight systems have strips set in series, meaning that if one of the them fails, all the system goes dark…

Using a multimeter, we can confirm that the strips are indeed set in series, so now we have to test each strip individually. Professionals use LED testers such as this one (about 40$ on amazon) but as I didn’t had one at the time, I decided to make one, McGyver style!