There are many parts can cause the same symptom: "TV backlight problem". Please read below for details: (Click on photo to enlarge).
1- The connectors and wiring assy failed (it is open or shorted) to supply power to backlight panel (The backlight needs power to lit up, without this power, the backlight doesn't lit anymore). The average labor to fix this problem varies between $60 to $140 (depending on the connectors or wiring problem are inside or outside of back-light panel assy.
2- The backlight power supply board doesn't work, no backlight power. Around 70% of the cases, the cost of power supply board varies between $40 up to $180 (depending on the the brand name, TV size, model number, part number, part stock availability, part shipping ...)
3- The controller board (main-com) controls the backlight operation. (Some TV models, Tcon board involved in backlight controlling too). It controls the power current goes through the backlight panel. It makes TV's picture bright, dark, dim or even OFF completely depending on the scene. The operation is programmed in TV's memory and microprocessor of the main-com board, without this control commands, backlight power will be OFF all the time. Around 70% of the cases, the cost of controller board varies between $40 up to $180 (depending on the brand name, TV size, model number, part number, part stock availability, part shipping ...)
4- The back-light LED panel. There are more than 10'000 backlight models different type completely (depending on TV brand name, size, model, version..) This LED panel acts like the lamp of your TV. It supplies the light sources for your TV to see the picture on the screen. It is controlled by power supply, main-com board... Around 70% of the cases, the cost of LED backlight set varies between $50 up to $160 (depending on the brand name, TV size, model number, part number, part stock availability, part shipping and how many LED strips must be replaced ...)
IMPORTANT MESSAGE: be careful, if you have no experience in TV repair, no training... the chance you crack the TV's screen assy when you disassemble it around 70-80% (especially with the big screen, some thin LCD screens are glued to the TV frame, extremely difficult to remove it )! If you want to do it yourself, you have to take your own risk.
To save your money and time, please bring your TV to our shop. Our technicians with professional testing equipment and highly experience will troubleshoot to find out which one is the cause of your TV backlight problem quickly and efficiency.