Hi. It looks like the backlight on your LED TV has failed. LED TVs feature long thin circuit boards with surface-mount LEDs packaged every few inches. Direct backlit TVs have quite a few strips with the LEDS spaced out over the area of the LCD panel. Edge lit LED Tvs have the majority of the LEDs on the sides of the LCD panel. It looks like your TV is direct LED backlight.
While LEDs can be more efficient and durable than other forms of lighting, it is up to the manufacturer to produce and implement a well designed power system where LEDs are driven within their specification, and create an environment where the LEDs can properly dissipate heat. Unfortunately, it seems that many TV manufacturers are intentionally creating poorly designed LED backlights and overdrive the LED dies to the point of thermal failure. It is not uncommon to have 4 or 5 LEDs randomly die on a 12 LED strip backlight because the TV manufacturer decided to integrate a power supply that provides too much current to the LEDs. I would not be surprised if a class action lawsuit is near for a few manufacturers.
In terms of the repair, there are a few things you can do:
- Take apart tv and observe power supply board (Be very careful, charged capacitors can be lethal)
- Look for any bulged capacitors or back spots. If you observe any of these conditions, your power supply may have failed instead of the LEDs
- Take entire tv & LCD assembly apart and replace led strips or LEDs on the LED strips.
Here are 2 related videos:
The reason why Vizio told you to buy a new TV is because the LEDs which have failed are the hardest part to get to inside the TV. It requires you to disassemble the lcd display assembly, which is very fragile. In order to disassembly the display assembly, you need a lot of space and a lot of patience.
Also, even if you replace the LEDs or LED strips, it is extremely likely that your backlight will fail again within 2 years. A lot of the folks who repair LED TVs mention to go into the settings of your tv and manually turn the backlight of the LCD at least half way down. Lowering the backlight brightness will increase the lifespan of your backlight.
There is a growing trend of using a large array of shorter PCBs to construct an LED TV backlight instead of just connecting a few long PCBs together.
This is largely a cost cutting measure due to shorter length PCBs having lower cost of overall production than longer boards. Instead of a TV vendor having to pay additional PCB manufacturing fees for a custom long-length (~24-36in) PCB order, the TV vendor will opt to produce smaller length (~16in) PCBs instead. While this cost cutting measure does make a lot of sense, a certain care has to be placed when relying on inexpensive board-to-board interconnects.
Unfortunately, these connectors are not always designed and implemented correctly. One example is if a TV manufacturer has backlight PCB strips produced at a new PCB production contractor and that PCB is 1.5mm thick instead of 1.6mm thick. Sure, this is only a 0.1mm difference, but that is enough for the spring loaded contacts in the board-to-board connector to not apply enough pressure on the PCB contacts and not conduct properly.
This Hackaday article goes into how these interconnects sometimes fail and can be easily repaired by just removing the connector and hard wiring the LED strips together with a soldering iron:
Good on you Tweepy [author] for finding out this excellent solution!
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