lcd panel backlight not working supplier

Most likely the inverter cable shorted in the hinge and blowed the logic board"s microfuse that protects the inverter circuitry. I"ve been able to find the microfuse location on the 1197Ghz, 1.2Ghz and on one of the two 1.33Ghz revision models. Look at the left of the inverter socket on the logic board, the microfuse has letters TH written on it. Use a multimeter and check the continuity. If there"s no continuity then the fuse is blown. Bridging the microfuse with a wire should restore the power to the inverter socket then to the inverter board and the backlight if nothing else is damaged on the logic board.

Liquid crystal displays (LCDs) are the most widely used display technology. Their applications cover TV, mobile phone, appliances, automotive, smart home, industrial meters, consumer electronics, POS, marine, aerospace, military etc. LCD screen display problem can occur for several reasons.

Effect of environmental conditions on the LCD assembly. Environmental conditions include both the effects of temperature and humidity, and cyclic loading.

Effect of manufacturing process. With the development of LCD for more than 40 years and the modern manufacturing equipment, this kind if defects are getting rear.

Common failures seen in LCDs are a decrease in screen contrast, non-functioning pixels or the whole display, and broken glass. Different kinds of LCD display problem need to have different kinds of fix methods or make the decision not worthwhile to repair.

Broken glassIf you accidently drop the LCD and you find it broken on the surface but the display still works. You might just break the touch panel; you can find a repair house or find a youtube video to replace the touch panel. If you find the display not showing, especially you find the fluid leaking out. You need to reply the whole display modules.

Dim LCD displayLCD can’t emit light itself. It uses backlight. Normally, the backlight is not fully driven, you can increase the LED backlight to make a dim LCD display brighter. But if you LCD display has been used for a long time, it is possible that the LED backlight has to be the end of life (not brightness enough) if you turn on 100% backlight brightness. In that case to fix LCD screen, you have to find a way to change the backlight. For some display, it is an easy job but it can be difficult for other displays depending on the manufacturing process.

Image sticking (Ghosting)Sometimes, you will find the previous image still appearing at the background even if you change to another image. It is also called burn in. This kind of failure doesn’t need to repair by professionals. You can simply shut off the display overnight, this kind of problem will go away. Please do remember that displaying a static image for a long time should be avoided.

LCD has white screen – If a LCD has a white screen which means the backlight is good. Simply check your signal input sources which are the most causes. It can also be caused by the display totally damaged by ESD or excess heat, shock which make the LCD controller broken or the connection failure which has to be repaired by professionals.

Blur ImagesAs the LCD images are made of RGB pixels, the screen shouldn’t be blur like old CRT displays. If you do see blur images, they might be caused by two reasons. 1) LCD has certain response time, if you are playing games or watch fast action movies, some old LCD displays can have image delays. 2) The surface of the LCD is made of a layer of plastic film with maximum hardness of 3H. If you clean the surface often or use the wrong detergent or solvent which cause the surface damage. To fix damage on LED screen it’s need to be changed with professionals.

If you have any questions about Orient Display displays and touch panels. Please feel free to contact: Sales Inquiries, Customer Service or Technical Support.

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:

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…

One LED like those ones typically needs between 2.5-3.6v input voltage to light up. By looking up this model online, I found out that the ones used on those strips need 3.6v; so as there are 9 LEDs per strip: 3.6 x 9 = 32.4v input voltage required to light a single strip. That’s the maximum voltage we do NOT want to exceed, otherwise LEDs could be damaged during testing.

So, I took 3 9v batteries that were laying in a drawer, put them in series to make a virtual 27v battery (3 x 9v). It’s less then the optimal 32.4v required but not that much lower, it might be able to light the strip a bit so we can identify which is not working. Here is a look at the set-up:

Now we simply have to test each strips individually to see if they light up or not. For each that doesn’t completly, it will mean it has at least one defective LED.

After repeating this operation on all strips, I found only 1 defective LED, the same we thought looked burnt when we first had a look at the backlight (3rd strip from the top, 6th LED from the left). For a better understanding at what a burnt LED looks like here are 2 pictures of a burnt one and an OK one. Mind the roasted color compared to the regular one.

For starters I’ll go with the third one, just to make sure there is no other issues with the TV, but afterwards it’s better to replace the LED with a new one, otherwise you might notice a darker spot on the image.

We are using TPS61165 for LCD backlight driver in our product. Recently, we have notified by our customer that LCD backlight got failed in two units and they have returned the units to us. We have investigated this issue and found two LEDs burnt out in the backlight strip. While discussing with the LCD supplier on this issue, they have mentioned like over voltage to the strip caused the failure. I have tested the failed unit with new backlight strip, it is working fine.

We manufacture and stock backlight assemblies for many NEC LCD panels. We produce premium quality replacements to extend the life of your flat panel screen devices.  If you do not see your panel model listed here, please contact us to learn about our cost effective design and manufacturing process.  Simply mail us a sample of the backlight you are looking to replace, and we can recreate and supply you with what you need to meet you needs.

• For the last 15+ years, Plazmo Industries has been providing premium CCFL lamps, LED strips & bars, touch screens and complete backlight assemblies for the most demanding of LCD applications. Why replace the entire LCD screen when you can repair it for a fraction of the cost? Use Plazmo"s high quality repair components to fix your dark or dim LCD screen.

• Preventative maintenance is key to help you avoid inconvenient, costly emergency service situations before problems arise. Replacing CCFL and LED lamps extends the life and lowers the total cost of ownership of your expensive LCD equipment. Keeping extra lamps on hand will minimize downtime and interruptions in service.

• Our CCFL lamps and LED strips are designed specifically for repairs of LCD panels made by many of largest LCD panel manufacturers in the world such as; AU Optronics (AUO), Samsung, Sanyo, LG, Innolux, Torisan, Sharp, Che Mei, Chunghwa, NEC, Mitsubishi, Toshiba, Boe Hydis, Hitachi, Fujitsu, HannStar and many more.

• We stock LCD backlights (both CCFL and LED) specifically for the replacement of LCD applications. Our customers have figured out they can dramatically extend the life of their mission-critical equipment by replacing and refurbishing rather than tossing out the machine. We sell backlights for industrial and medical equipment, desktops, printers, photo copy machines, and more. Any piece of equipment with a display screen has a backlight that can be replaced.

An LED-backlit LCD is a liquid-crystal display that uses LEDs for backlighting instead of traditional cold cathode fluorescent (CCFL) backlighting.TFT LCD (thin-film-transistor liquid-crystal display) technologies as CCFL-backlit LCDs, but offer a variety of advantages over them.

While not an LED display, a television using such a combination of an LED backlight with an LCD panel is advertised as an LED TV by some manufacturers and suppliers.

Unlike OLED and microLED displays, LCDs cannot achieve true blacks for pixels which are illuminated by the backlight. Some LED-backlit LCDs use local dimming zones to increase contrast between bright and dim areas of the display, but this can result in a "blooming" or "halo" effect on dark pixels in or adjacent to an illuminated zone.

The local dimming method of backlighting allows to dynamically control the level of light intensity of specific areas of darkness on the screen, resulting in much higher dynamic-contrast ratios, though at the cost of less detail in small, bright objects on a dark background, such as star fields or shadow details.

A 2016 study by the University of California (Berkeley) suggests that the subjectively perceived visual enhancement with common contrast source material levels off at about 60 LCD local dimming zones.

LED-backlit LCDs are not self-illuminating (unlike pure-LED systems). There are several methods of backlighting an LCD panel using LEDs, including the use of either white or RGB (Red, Green, and Blue) LED arrays behind the panel and edge-LED lighting (which uses white LEDs around the inside frame of the TV and a light-diffusion panel to spread the light evenly behind the LCD panel). Variations in LED backlighting offer different benefits. The first commercial full-array LED-backlit LCD TV was the Sony Qualia 005 (introduced in 2004), which used RGB LED arrays to produce a color gamut about twice that of a conventional CCFL LCD television. This was possible because red, green and blue LEDs have sharp spectral peaks which (combined with the LCD panel filters) result in significantly less bleed-through to adjacent color channels. Unwanted bleed-through channels do not "whiten" the desired color as much, resulting in a larger gamut. RGB LED technology continues to be used on Sony BRAVIA LCD models. LED backlighting using white LEDs produces a broader spectrum source feeding the individual LCD panel filters (similar to CCFL sources), resulting in a more limited display gamut than RGB LEDs at lower cost.

The evolution of energy standards and the increasing public expectations regarding power consumption made it necessary for backlight systems to manage their power. As for other consumer electronics products (e.g., fridges or light bulbs), energy consumption categories are enforced for television sets.

A first dynamic "local dimming" LED backlight was public demonstrated by BrightSide Technologies in 2003,Sony in September 2008 on the 40-inch (1,000 mm) BRAVIA KLV-40ZX1M (known as the ZX1 in Europe). Edge-LED lighting for LCDs allows thinner housing; the Sony BRAVIA KLV-40ZX1M is 1 cm thick, and others are also extremely thin.

LED-backlit LCDs have longer life and better energy efficiency than plasma and CCFL LCD TVs.mercury, an environmental pollutant, in their manufacture. However, other elements (such as gallium and arsenic) are used in the manufacture of the LED emitters; there is debate over whether they are a better long-term solution to the problem of screen disposal.

Because LEDs can be switched on and off more quickly than CCFLs and can offer a higher light output, it is theoretically possible to offer very high contrast ratios. They can produce deep blacks (LEDs off) and high brightness (LEDs on). However, measurements made from pure-black and pure-white outputs are complicated by edge-LED lighting not allowing these outputs to be reproduced simultaneously on screen.

Quantum dots are photoluminescent; they are useful in displays because they emit light in specific, narrow normal distributions of wavelengths. To generate white light best suited as an LCD backlight, parts of the light of a blue-emitting LED are transformed by quantum dots into small-bandwidth green and red light such that the combined white light allows a nearly ideal color gamut to be generated by the RGB color filters of the LCD panel. The quantum dors may be in a separate layer as a quantum dot enhacement film, or replace pigment-based green and red resists normally used in LCD color filters. In addition, efficiency is improved, as intermediate colors are no longer present and do not have to be filtered out by the color filters of the LCD screen. This can result in a display that more accurately renders colors in the visible spectrum. Companies developing quantum dot solutions for displays include Nanosys, 3M as a licensee of Nanosys, QD Vision of Lexington, Massachusetts, US and Avantama of Switzerland.Consumer Electronics Show 2015.quantum dot displays at CES 2017 and later formed the "QLED Alliance" with Hisense and TCL to market the technology.

Mini LED displays are LED-backlit LCDs with mini-LED–based backlighting supporting over a thousand full array local dimming (FALD) zones, providing deeper blacks and a higher contrast ratio.

LED backlights are often dimmed by applying pulse-width modulation to the supply current, switching the backlight off and on more quickly than the eye can perceive. If the dimming-pulse frequency is too low or the user is sensitive to flicker, this may cause discomfort and eyestrain similar to the flicker of CRT displays at lower refresh rates.

Novitsky, Tom; Abbott, Bill (12 November 2007). "Driving LEDs versus CCFLs for LCD backlighting". EE Times. Archived from the original on 28 November 2010. Retrieved 21 November 2020.

Controlling Power Consumption for Displays With Backlight Dimming; Claire Mantel et al; Journal of Display Technology; Volume: 9, Issue: 12, Dec. 2013; https://ieeexplore.ieee.org/document/6520956

LCD Television Power Draw Trends from 2003 to 2015; B. Urban and K. Roth; Fraunhofer USA Center for Sustainable Energy Systems; Final Report to the Consumer Technology Association; May 2017; http://www.cta.tech/cta/media/policyImages/policyPDFs/Fraunhofer-LCD-TV-Power-Draw-Trends-FINAL.pdf Archived 1 August 2017 at the Wayback Machine

Desktop and laptop computer LCD monitors sport a long light bulb to display the video. When this bulb burns out, the screen dims to almost black. Failing backlights can also cause the picture to flicker, blink on and off or offer an odd color cast to the screen.

Troubleshooting Before assuming the backlight bulb is the issue, check to make sure the monitor is connected properly and receiving power. Watch for the power light near the On/Off switch when you plug in the monitor, and verify all cables are connected tightly and appear undamaged. If possible, connect a different monitor to your computer using the same cables to verify the computer"s video card is sending a picture. If everything else seems in good working order, the monitor could have suffered a backlight failure.

Testing, Testing Various things can cause your monitor to go dark, ranging from a burned-out backlight bulb to a monitor-killing short circuit. In most cases, a monitor with a burned-out bulb still has an image on the screen, it"s just very dim. Look closely at your screen; if you see absolutely no picture at all, the monitor itself may have gone belly up. A bad bulb can be tested, but only if you have a working replacement bulb and are comfortable opening your monitor and doing some checking.

Some Disassembly Required As you would guess, checking the backlight bulb on your monitor requires actually getting into the screen and pulling out the suspect light. Monitor disassembly varies by model; check your monitor"s manufacturer"s website for instructions. Once you have the bulb out, disconnect it from the inverter board that powers it and connect your working bulb. If the new one lights, your old one was dead. If the new one is as dark as the first, your inverter board may have failed and will need replacement.

Seek Professional Help Because cracking open your laptop or desktop monitor can leave other parts vulnerable to unintentional damage, you have to be confident in your abilities to attempt backlight testing. One wrong move could fry another component, leaving you worse off than befire. If the idea of opening up a monitor and fiddling with the insides makes you nervous, seek out the help of an experienced technician. Replacing a bad bulb or inverter board is a relatively inexpensive fix to extend the life of your equipment.

For the video display developer LCD panels are available in many sizes and resolutions, they are also available with many choices of maximum brightness. The following considers the topic of LCD panel brightness, the choices, the methods for adjusting brightness and some brightness adjustment scenarios.

LCD panels are generally rated as to their maximum brightness level which is expressed in Nits, it is equal to Candela/sqm (cd/m2), and this will be at a particular color temperature as noted in the specification, usually 10,000 K. In terms of a practical understanding, the following is a rough guide:

Outdoor displays range from a low end of 700 nits to typically 1,000 or 1,500nits and up with 2,000~2,500nits and even up to 5,000nits seen with some models. This may include standard LCD panels, custom LCD panels as well as custom cut LCD panels.

Virtually all LCD panels have a LED backlight these days, these are powered by an LED driver board. Brightness control via the driver board will be by one of two methods:

PWM (Pulse Width Modulation): This varies the duty cycle of the backlight “on time” – it is predominant in modern LCD panel LED backlight designs to enable support for digital brightness controls.

Analog: Uses a simple variable voltage to adjust brightness, for example this might be a dial or slider type potentiometer / variable resistor. To see how to enable analog backlight adjustment visit: https://www.digitalview.com/blog/brightness-adjustment/

One of the advantages of LED for the backlight is the range of adjustment that is possible, however it is important to note that the range varies significantly from model to model. Some industrial panels can be turned to very low light levels making them suitable for use in special environments such as at night. Lower cost panels limit the range of brightness to what might be required for typical usage, whereas panels with full range dimming from full off to full on require more complex backlight drivers.

Backlight lifetime: Many LCD panels have a backlight lifetime rating of 50,000 hours (typically measured to half brightness), this can be extended by running the LED backlight at a lower brightness level. Some panels may only offer 30,000 hours as a lower cost solution while other panels may offer up to 100,000 hours for high end applications.

An LCD panel backlight may be constructed so the LED’s are mounted directly behind a light guide diffuser, or they may be mounted along one or more edges of the light guide.

Active backlight: This is a function of some LCD panel backlights to automatically adjust the backlight brightness in response to the image. For more advanced systems there is an LED array making up the LED backlight, this adjusts the brightness in areas localized to the image being shown. This can greatly enhance the brightness across the display and is being used primarily with video, for example on consumer TV sets. It is not useful to all image types, for example a spreadsheet or content like maps or data is not likely to benefit.

Local dimming: Some LCD panels with direct LED may support local dimming so the LED’s are dimmed in response to the image close to them. This will not be at the same resolution as the LCD panel itself but will help greater contrast over the display by enhancing the brightness in bright areas of the image and darkening the image in dark parts of the image.

For the LCD monitor manufacturer it is important to consider that any covering over the LCD panel will reduce the brightness. For example the protective glass over a digital signage display, or a touch screen, or a semi-silvered mirror. So if a specific brightness is required the measurement should be taken with these in place.

Examples of light meters costing a few hundred dollars include SpyderX by Datacolor (needs a PC), a handheld meter is the SM208 by Sanpometer (search SM208 meter). Note: Many light meters, including smartphone apps, will be meters used for photography and not give readings in nits (or candelas). LCD panel specifications are typically measured using nits.

PWM and Analog: Most Digital View LCD controllers support PWM and Analog as a method for adjusting the backlight brightness level (this is noted in the column headed “Other” on the controller board summary table: https://www.digitalview.com/controllers/lcd-controllers-home.html. Also see https://www.digitalview.com/blog/brightness-adjustment/ for a guide to using a dial or slider type variable resistor to adjust the backlight.

DPMS (Display Power Management System): The backlight will be automatically turned off after a period if there is no valid video signal being received.

Ambient light sensor: The backlight is adjusted for brightness or powered off depending on ambient light conditions. This uses a light sensor attached to the LCD controller board, see https://www.digitalview.com/blog/light-sensor-app-note/ for more details.

The specifics of the backlight control are documented separately for each LCD controller model (product summary here) in the product manual available for download on the product page.

Note: There are two ways to adjust the perceived brightness of a LCD panel or LCD monitor, the backlight and the black-level. Very often, particularly in the past, the monitor brightness setting adjusted the black-level, this adjusts the LCD but not the backlight.

Night-safe lighting (update) : Dual-rail backlights can also be supported. These special backlight enable normal brightness and extreme low level brightness with custom night-safe lighting. Contact us for details.

Note: We have a blog on methods for implementing an ambient light sensor with Digital View LCD controller boards to automatically adjust the backlight or system power, see: Ambient Light Sensor

Update March 2019: Most of the above remains unchanged except for the increased availability of high bright LCD panels of around the 1,000 nit to 2,500 nit range. AUO for example has a number of large size LCD panels with 1,500 nit brightness for the digital signage market. Tianma has panels under 20″ with 1,000 nit to 1,500 nit brightness for various outdoor applications.

The other change is that high bright panels are now increasing edge-lit, this makes the panels thinner and these panels tend to use less power than the previous models. One of the benefits for monitor designers is easier heat management and reduced overall display system costs.

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.

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.

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.

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.

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.

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.

Founded in 2014, VISLCD is a professional LCD supplier. We provide LCD modules, touch LCD and customized LCD in various sizes with stable quality and competitive price. Welcome to contact us for any LCD demand, thank you.

Light leak or backlight bleeding is often noticeable around the edges or the sides of a screen. Especially while it is displaying a dark background or is in a dark environment.

Ideally, light leakage must not be inspected in a dark room. All Dell monitors are inspected as per industry standard with 150-Lux ambient lighting (similar to typical office lighting). However, for gaming monitors, ambient lighting is 70 Lux. Any visual inspection must be done in the same manner to help with the troubleshooting process.

NOTE: This article provides information about common issues that are seen on LCD screens. It is not something specific to a particular Dell computer but is something that can be seen on any LCD screen by any manufacturer.

Newhaven 16x1 character Liquid Crystal Display shows characters with dark pixels on a bright amber background when powered on. This transflective LCD Display is visible with ambient light or a backlight while offering a wide operating temperature range from -20 to 70 degrees Celsius. This NHD-0116GZ-FSA-FBW display has an optimal view of 6:00. This display operates at 5V supply voltage and is RoHS compliant.