I got a few years back a TV to use as a monitor LG 49NANO863NA. I used it for a while and the pwm started to be a problem. I tried to back down the backlight, still noticeable pwm. Then I cranked the backlight to 100% and the problems went away but the tv was too bright. I used it with sunglasses for a while, it was usable that way.

Then I decided that f… the 2 year guarantee I will open the TV and see how the backlight is constructed. I opened the TV and when setting up the TV I had to turn off local dimming. So the TV had 6 vertical zones that went bright when there was a bright object on screen. I didn't need that feature for a monitor. So I found there was 6 transistors that got the signal from some chip and "amplified" it to the backlight. Between the transistor input and chip there was a resistor. I connected arduino input to the resistor input and ground to ground. Measured PWM and it was 120Hz, so twice the TV refresh rate. On every level the PWM was the same.

I removed the resistors on every transistor input and soldered a wire from ESP32 to the transistor input. Then I tried to measure PWM with ESP32 and use higher PWM value to transistor. It was not successful, because the TV somehow "knows" or checks the backlight and then goes to error mode and doesn't git pwm signal anymore. The LCD worked fine.

Then I went with manual approach. Drilled a hole into the TV bottom and put the potentiometer there. Connected the potentiometer to ESP32 as input, so I can control brightness. ESP32 pwm outputs to TV transistor inputs.

The TV has been working like that for a year as a monitor. For my eyes it is definitely better.

For ESP32 output I used 30000Hz PWM.

    2 months later

    Im sure you made photos along the way, any guides for anyone who decides to do the same type havk

    kaar3l

    Most of the TVs and some monitors have a hidden service menu. In some of them you could modfify backlight settings to lower the light by sw. You could find them in youtube.

      dev